Virtual Journal of Ultrafast Science

A simple route to fabricate artificial compound eye structures

Pubo Qu, Feng Chen, Hewei Liu, Qing Yang, Jing Lu et al.
A biologically inspired compound-eye structure, which composes of ~5,867 honeycomb-patterned microlenses, was fabricated on a hemispherical shell. The fabrication process was simple and low-cost, which involves a femtosecond laser-enhanced wet etching and casting process followed by a thermomechanic ... [Opt. Express 20, 5775 (2012)] published Thu Mar 15, 2012.

Precision depth measurement of through silicon vias (TSVs) on 3D semiconductor packaging process

Jonghan Jin, Jae Wan Kim, Chu-Shik Kang, Jong-Ahn Kim, and Sunghun Lee
We have proposed and demonstrated a novel method to measure depths of through silicon vias (TSVs) at high speed. TSVs are fine and deep holes fabricated in silicon wafers for 3D semiconductors; they are used for electrical connections between vertically stacked wafers. Because the high-aspect ratio ... [Opt. Express 20, 5011 (2012)] published Thu Mar 15, 2012.

Photoacoustic/ultrasound dual-modality contrast agent and its application to thermotherapy

Yu-Hsin Wang, Ai-Ho Liao, Jui-Hao Chen, Churng-Ren Chris Wang, and Pai-Chi Li
This study investigates a photoacoustic/ultrasound dual-modality contrast agent, including extending its applications from image-contrast enhancement to combined diagnosis and therapy with site-specific targeting. The contrast agent comprises albumin-shelled microbubbles with encapsulated gold nanor ... [J. Biomed. Opt. 17, 045001 (2012)] published Mon Mar 19, 2012.

Influence of effective number of pulses on the morphological structure of teeth and bovine femur after femtosecond laser ablation

Gustavo Nicolodelli, Rosane de Fatima Zanirato Lizarelli, and Vanderlei Salvador Bagnato
Femtosecond lasers have been widely used in laser surgery as an instrument for contact-free tissue removal of hard dental, restorative materials, and osseous tissues, complementing conventional drilling or cutting tools. In order to obtain a laser system that provides an ablation efficiency comparab ... [J. Biomed. Opt. 17, 048001 (2012)] published Tue Mar 27, 2012.

Towards endoscopic ultrafast laser microsurgery of vocal folds

Christopher L. Hoy, W. Neil Everett, Murat Yildirim, James Kobler, Steven M. Zeitels et al.
Vocal fold scarring is a predominant cause of voice disorders yet lacks a reliable treatment method. The injection of soft biomaterials to improve mechanical compliance of the vocal folds has emerged as a promising treatment. Here, we study the use of precise femtosecond laser microsurgery to ablate ... [J. Biomed. Opt. 17, 038002 (2012)] published Fri Mar 16, 2012.

Quenching electron runaway in positive high-voltage-impulse discharges in air by laser filaments

S. Eto, A. Zhidkov, Y. Oishi, M. Miki, and T. Fujii
Strong hard (epsilon>100 keV) x rays being observed from impulse atmospheric discharges with maximal voltages from U=0.5 to 0.9 MV just before the breakdown were completely stopped with the use of femtosecond-laser-filament plasma. Runaway electrons generating such x rays and being estimated to ach ... [Opt. Lett. 37, 1130 (2012)] published Thu Mar 29, 2012.

Colorizing silicon surface with regular nanohole arrays induced by femtosecond laser pulses

Cheng-Yun Zhang, Jian-Wu Yao, Hai-Ying Liu, Qiao-Feng Dai, Li-Jun Wu et al.
We report on the formation of one- and two-dimensional (1D and 2D) nanohole arrays on the surface of a silicon wafer by scanning with a femtosecond laser with appropriate power and speed. The underlying physical mechanism is revealed by numerical simulation based on the finite-difference time-domain ... [Opt. Lett. 37, 1106 (2012)] published Thu Mar 29, 2012.

Three-dimensional direct femtosecond laser writing of second-order nonlinearities in glass

Jiyeon Choi, Matthieu Bellec, Arnaud Royon, Kevin Bourhis, Gautier Papon et al.
We demonstrate that direct femtosecond laser writing in silver-containing zinc and gallium phosphate glass enables generation of three-dimensional (3D) optical second-order nonlinear microstructures having an chi value about 2.5 times that of quartz. The proposed physical model involves photo-reduct ... [Opt. Lett. 37, 1029 (2012)] published Thu Mar 29, 2012.

Surface processing technique based on opto-hydrodynamic phenomena occurring in laser-induced breakdown of a microdroplet

Daehwan Ahn, Deoksuk Jang, Tae-Youl Choi, and Dongsik Kim
We report the development of a surface processing technique based on the optical breakdown of a microdroplet and subsequent ejection of a pulsed microjet. The microjet was sufficiently fast to remove nanoparticles from surfaces and erode most materials. The small volume of the droplet enabled precis ... [Appl. Phys. Lett. 100, 104104 (2012)] published Wed Mar 7, 2012.

Fragment momentum distributions obtained from coupled electron-nuclear dynamics

Kilian Hader and Volker Engel
We theoretically investigate fragmentation processes induced by femtosecond laser pulses within a model which incorporates electronic and nuclear motion. Single-pulse excitation leads to diffraction patterns in the electron momentum distribution which depend on the nature of the electronic state and ... [J. Chem. Phys. 136, 104306 (2012)] published Mon Mar 12, 2012.

The Multielectron Ionization Dynamics Underlying Attosecond Strong-Field Spectroscopies

Andrey E. Boguslavskiy, Jochen Mikosch, Arjan Gijsbertsen, Michael Spanner, Serguei Patchkovskii et al.
Subcycle strong-field ionization (SFI) underlies many emerging spectroscopic probes of atomic or molecular attosecond electronic dynamics. Extending methods such as attosecond high harmonic generation spectroscopy to complex polyatomic molecules requires an understanding of multielectronic excitatio ... [Science 335, 1336 ] published .

Probing the timescale of the exchange interaction in a ferromagnetic alloy

Stefan Mathias, Chan La-O-Vorakiat, Patrik Grychtol, Patrick Granitzka, Emrah Turgut et al.
The underlying physics of all ferromagnetic behavior is the cooperative interaction between individual atomic magnetic moments that results in a macroscopic magnetization. In this work, we use extreme ultraviolet pulses from high-harmonic generation as an element-specific probe of ultrafast, optica ... [Proc. Natl. Acad. Sci. U.S.A. 109, 4792 (2012)] published Thu Mar 29, 2012.

Noisy Optical Pulses Enhance the Temporal Resolution of Pump-Probe Spectroscopy

Kristina Meyer, Christian Ott, Philipp Raith, Andreas Kaldun, Yuhai Jiang et al.
Time-resolved measurements of quantum dynamics are based on the availability of controlled events that are shorter than the typical evolution time scale of the processes to be observed. Here we introduce the concept of noise-enhanced pump-probe spectroscopy, allowing the measurement of dynamics sign ... [Phys. Rev. Lett. 108, 098302 ] published .

Extracting Continuum Electron Dynamics from High Harmonic Emission from Molecules

R. M. Lock, S. Ramakrishna, X. Zhou, H. C. Kapteyn, M. M. Murnane et al.
We show that high harmonic generation is the most sensitive probe of rotational wave packet revivals, revealing very high-order rotational revivals for the first time using any probe. By fitting high-quality experimental data to an exact theory of high harmonic generation from aligned molecules, we ... [Phys. Rev. Lett. 108, 133901 ] published .

Attosecond Lighthouses: How To Use Spatiotemporally Coupled Light Fields To Generate Isolated Attosecond Pulses

H. Vincenti and F. Quere
Under the effect of even simple optical components, the spatial properties of femtosecond laser beams can vary over the duration of the light pulse. We show how using such spatiotemporally coupled light fields in high harmonic generation experiments (e.g., in gases or dense plasmas) enables the prod ... [Phys. Rev. Lett. 108, 113904 ] published .

Two-photon double ionization of helium by attosecond laser pulses: Evidence of highly correlated electron motion

Sigurd Askeland, Raymond Nepstad, and Morten Forre
We apply a recently developed ab initio numerical framework to investigate the angular distributions of the emitted electrons in the immediate proximity of the threshold for the two-photon double ionization of helium. Provided one of the electrons is emitted perpendicular to the laser polarization d ... [Phys. Rev. A 85, 035404 ] published .

High-order-harmonic generation from inhomogeneous fields

M. F. Ciappina, J. Biegert, R. Quidant, and M. Lewenstein
We present theoretical studies of high-order-harmonic generation (HHG) produced by nonhomogeneous fields resulting from the illumination of plasmonic nanostructures with a short laser pulse. We show that both the inhomogeneity of the local fields and the confinement of the electron movement play an ... [Phys. Rev. A 85, 033828 ] published .

Strong-field ionization and high-order-harmonic generation during polyatomic molecular dynamics of NO

Michael Spanner, Jochen Mikosch, Andrey E. Boguslavskiy, Margaret M. Murnane, Albert Stolow et al.
We present state-of-the-art ab initiotype computations of strong-field ionization (SFI) and the single-molecule response contribution to high-order-harmonic generation (HHG) in the polyatomic molecule NO. The numerical method uses a mixed orbital- and grid-based approach to model the multielectron b ... [Phys. Rev. A 85, 033426 ] published .

Comparison of high-order harmonic generation of Ar using truncated Bessel and Gaussian beams

Cheng Jin and C. D. Lin
We study high-order harmonic generation (HHG) spectra by a focused truncated Bessel beam versus a Gaussian beam, including macroscopic propagation of the fundamental laser and harmonic fields in the gas medium, with the single-atom-induced dipole response calculated from the recently developed quant ... [Phys. Rev. A 85, 033423 ] published .

Analytic theory of high-order-harmonic generation by an intense few-cycle laser pulse

M. V. Frolov, N. L. Manakov, A. M. Popov, O. V. Tikhonova, E. A. Volkova et al.
We present a theoretical model for describing the interaction of an electron, weakly bound in a short-range potential, with an intense, few-cycle laser pulse. General definitions for the differential probability of above-threshold ionization and for the yield of high-order-harmonic generation (HHG) ... [Phys. Rev. A 85, 033416 ] published .

High-order-harmonic generation from coherent electron wave packets in atoms and molecules as a tool for monitoring attosecond electrons

Szczepan Chelkowski, Timm Bredtmann, and Andre D. Bandrauk
We study numerically pump-probe schemes for monitoring electron-nuclear motion in a dissociating molecule using a midinfrared, intense few-femtosecond probe laser pulse which generates molecular high-order harmonics (MHOHG) from a coherent superposition of electron-nuclear wave packets prepared by a ... [Phys. Rev. A 85, 033404 ] published .

Attosecond electron dynamics: A multiresolution approach

Nicholas Vence, Robert Harrison, and Predrag Krstic
We establish a numerical solution to the time-dependent Schrodinger equation employing an adaptive, discontinuous spectral element basis that automatically adjusts to the requested precision. The explicit time evolution is accomplished by a band-limited, gradient-corrected, symplectic propagator and ... [Phys. Rev. A 85, 033403 ] published .

Time shifts in photoemission from a fully correlated two-electron model system

S. Nagele, R. Pazourek, J. Feist, and J. Burgdorfer
We theoretically investigate time-resolved photoemission originating from two different shells (1s and 2p) of a fully correlated atomic two-electron model system ionized by an extreme-ultraviolet attosecond light pulse. The parameters of the model system are tuned such that the ionization potentials ... [Phys. Rev. A 85, 033401 ] published .

Generation of two attosecond pulses with tunable delay using orthogonally-polarized chirped laser pulses

Jing Miao, Zhinan Zeng, Peng Liu, Yinghui Zheng, Ruxin Li et al.
We investigate theoretically the high-order harmonic generation (HHG) by two orthogonally-polarized linearly chirped laser pulses. We show that such generating field has a specific temporal variation of the ellipticity which provides generation of two XUV attosecond pulses with tunable delay between ... [Opt. Express 20, 5196 (2012)] published Thu Mar 15, 2012.

Fractional high-order harmonic combs and energy tuning by attosecond-precision split-spectrum pulse control

Philipp Raith, Christian Ott, Christopher P. Anderson, Andreas Kaldun, Kristina Meyer et al.
We experimentally control high-order harmonic generation by applying a versatile few-cycle pulse-shape control method: splitting up a single broadband continuous laser spectrum into two sections and applying sub-femtosecond relative time delays. For certain time delays, fractional high-harmonic comb ... [Appl. Phys. Lett. 100, 121104 (2012)] published Mon Mar 19, 2012.

Amplitude and Phase Reconstruction of Electron Wave Packets for Probing Ultrafast Photoionization Dynamics

Kyung Taec Kim, Dong Hyuk Ko, Juyun Park, Nark Nyul Choi, Chul Min Kim et al.
Ultrafast atomic processes, such as excitation and ionization occurring on the femtosecond or shorter time scale, were explored by employing attosecond high-harmonic pulses. With the absorption of a suitable high-harmonic photon a He atom was ionized, or resonantly excited with further ionization by ... [Phys. Rev. Lett. 108, 093001 ] published .

Experimental demonstration of wakefield effects in a THz planar diamond accelerating structure

S. Antipov, C. Jing, A. Kanareykin, J. E. Butler, V. Yakimenko et al.
We have directly measured THz wakefields induced by a subpicosecond, intense relativistic electron bunch in a diamond loaded accelerating structure via the wakefield acceleration method. We present here the beam test results from the diamond based structure. Diamond has been chosen for its high brea ... [Appl. Phys. Lett. 100, 132910 (2012)] published Fri Mar 30, 2012.

Selective deuteron production using target normal sheath acceleration

J. T. Morrison, M. Storm, E. Chowdhury, K. U. Akli, S. Feldman et al.
We report on the first successful demonstration of selective deuteron acceleration by the target normal sheath acceleration mechanism in which the normally overwhelming proton and carbon ion contaminant signals are suppressed by orders of magnitude relative to the deuteron signal. The deuterium ions ... [Phys. Plasmas 19, 030707 (2012)] published Fri Mar 30, 2012.

Observation of coherent transition radiation in the prewave zone

Changmook Yim (임창묵), Junho Ko (고준호), Seonghoon Jung (정성훈), Daehoon Han (한대훈), Changbum Kim (김창범) et al.
Transition radiation generated from a relativistic electron beam is used as a tool for diagnostics of the beam. Also, it can be used as a source of femtosecond (fs) THz radiation. We are generating the THz radiation with the pulse energy of 3 [mu]J by means of the coherent transition radiation (CTR ... [Phys. Rev. ST Accel. Beams 15, 030706 ] published .

Weibel-Induced Filamentation during an Ultrafast Laser-Driven Plasma Expansion

K. Quinn, L. Romagnani, B. Ramakrishna, G. Sarri, M. E. Dieckmann et al.
The development of current instabilities behind the front of a cylindrically expanding plasma has been investigated experimentally via proton probing techniques. A multitude of tubelike filamentary structures is observed to form behind the front of a plasma created by irradiating solid-density wire ... [Phys. Rev. Lett. 108, 135001 ] published .

Multiple filamentation generated by focusing femtosecond laser with axicon

Xiaodong Sun, Hui Gao, Bin Zeng, Shengqi Xu, Weiwei Liu et al.
Multiple filamentation has been observed when focusing a femtosecond laser pulse into a methanol solution with an axicon. It is found that multiple long filaments are located on the central spot and ring structures of the quasi-Bessel beam created by the axicon. Since the quasi-Bessel profile is det ... [Opt. Lett. 37, 857 (2012)] published Thu Mar 1, 2012.

Quasi-monochromatic pencil beam of laser-driven protons generated using a conical cavity target holder

M. Nishiuchi, A. S. Pirozhkov, H. Sakaki, K. Ogura, T. Zh. Esirkepov et al.
A 7 MeV proton beam collimated to 16 mrad containing more than 10 particles is experimentally demonstrated by focusing a 2 J, 60 fs pulse of a Ti:sapphire laser onto targets of different materials and thicknesses placed in a millimeter scale conical holder. The electric potential induced on the targ ... [Phys. Plasmas 19, 030706 (2012)] published Wed Mar 28, 2012.

Direct Measurement of Energetic Electrons Coupling to an Imploding Low-Adiabat Inertial Confinement Fusion Capsule

T. Doppner, C. A. Thomas, L. Divol, E. L. Dewald, P. M. Celliers et al.
We have imaged hard x-ray (>100 keV) bremsstrahlung emission from energetic electrons slowing in a plastic ablator shell during indirectly driven implosions at the National Ignition Facility. We measure 570 J in electrons with E>100 keV impinging on the fusion capsule under ignition drive conditio ... [Phys. Rev. Lett. 108, 135006 ] published .

Scaling submillimeter single-cycle transients toward megavolts per centimeter field strength via optical rectification in the organic crystal OH1

Clemens Ruchert, Carlo Vicario, and Christoph P. Hauri
We present the generation of high-power single-cycle terahertz (THz) pulses in the organic salt crystal 2-[3-(4-hydroxystyryl)-5.5-dimethylcyclohex-2-enylidene]malononitrile or OH1. Broadband THz radiation with a central frequency of 1.5 THz (lambda=200 [mu]m) and high electric field strength of 44 ... [Opt. Lett. 37, 899 (2012)] published Thu Mar 1, 2012.

Experimental observation of helical microbunching of a relativistic electron beam

E. Hemsing, A. Knyazik, F. O'Shea, A. Marinelli, P. Musumeci et al.
Experimental observation of the microbunching of a relativistic electron beam at the second harmonic interaction frequency of a helical undulator is presented. The microbunching signal is observed from the coherent transition radiation of the electron beam and indicates experimental evidence of a do ... [Appl. Phys. Lett. 100, 091110 (2012)] published Thu Mar 1, 2012.

Hundreds MeV monoenergetic proton bunch from interaction of 10 W/cm circularly polarized laser pulse with tailored complex target

Z. M. Zhang (张智猛), X. T. He (贺贤土), Z. M. Sheng (盛正卯), and M. Y. Yu (郁明阳)
A complex target (CT) configuration tailored for generating high quality proton bunch by circularly polarized laser pulses at intensities of 10 W/cm is proposed. Two-dimensional particle-in-cell simulations show that both the collimation and mono-energetic qualities of the accelerated proton bunch o ... [Appl. Phys. Lett. 100, 134103 (2012)] published Thu Mar 29, 2012.

Triggering and guiding electric discharge by a train of ultraviolet picosecond pulses combined with a long ultraviolet pulse

A. A. Ionin, S. I. Kudryashov, A. O. Levchenko, L. V. Seleznev, A. V. Shutov et al.
Non-self-sustained electric discharge and electric breakdown were triggered and guided by a train of picosecond ultraviolet (UV) pulses overlapped with a long free-running UV pulse of a hybrid Ti:Sapphire-KrF laser facility. Photocurrent sustained by this train is two orders of magnitude higher, and ... [Appl. Phys. Lett. 100, 104105 (2012)] published Thu Mar 8, 2012.

Inertial confinement fusion implosions with imposed magnetic field compression using the OMEGA Laser

M. Hohenberger, P.-Y. Chang, G. Fiksel, J. P. Knauer, R. Betti et al.
Experiments applying laser-driven magnetic-flux compression to inertial confinement fusion (ICF) targets to enhance the implosion performance are described. Spherical plastic (CH) targets filled with 10 atm of deuterium gas were imploded by the OMEGA Laser, compare Phys. Plasmas 18, 056703 or Phys. ... [Phys. Plasmas 19, 056306 (2012)] published Wed Mar 28, 2012.

Electron and ion dynamics during the expansion of a laser-heated plasma under vacuum

C. Bellei, M. E. Foord, T. Bartal, M. H. Key, H. S. McLean et al.
The trajectories of electrons and ions when a hot plasma expands under vacuum are studied in detail from a theoretical point of view and with the aid of numerical simulations. Exact analytic solutions are obtained in multi-dimensions, starting from the solution for the expansion of a quasi-neutral, ... [Phys. Plasmas 19, 033109 (2012)] published Fri Mar 30, 2012.

High-charge energetic electron bunch generated by 100 TW laser pulse

Baifei Shen, Yuchi Wu, Kegong Dong, Bin Zhu, Yuqiu Gu et al.
Energetic electron bunches with more than 20 nC charge are generated from 100 TW level laser pulse interaction with 2% critical density plasma. Three-dimensional particle-in-cell simulations show that the unexpected high bunch-charge can be attributed to the multiple intensity peaks of the laser pul ... [Phys. Plasmas 19, 033106 (2012)] published Wed Mar 21, 2012.

Studies of spectral modification and limitations of the modified paraxial equation in laser wakefield simulations

W. Zhu, J. P. Palastro, and T. M. Antonsen
Laser pulses propagating through plasma undergo spectral broadening through local energy exchange with driven plasma waves. For propagation distances on the order of the energy depletion length, spectral shifts can be comparable to the laser central frequency and wavenumber, a result of approximate ... [Phys. Plasmas 19, 033105 (2012)] published Fri Mar 16, 2012.

Ponderomotive ion acceleration in dense magnetized laser-irradiated thick target plasmas

Ujjwal Sinha and Predhiman Kaw
When a circularly polarized laser pulse falls on an overdense plasma, it displaces the electrons via ponderomotive force creating a double layer. The double layer constitutes of an ion and electron sheath with in which the electrostatic field present is responsible for ion acceleration. In this pape ... [Phys. Plasmas 19, 033102 (2012)] published Fri Mar 9, 2012.

Theory of ionization-induced trapping in laser-plasma accelerators

M. Chen, E. Esarey, C. B. Schroeder, C. G. R. Geddes, and W. P. Leemans
Ionization injection in a laser-plasma accelerator is studied analytically and by multi-dimensional particle-in-cell (PIC) simulations. To enable the production of low energy spread beams, we consider a short region containing a high atomic number gas (e.g., nitrogen) for ionization-induced trapping ... [Phys. Plasmas 19, 033101 (2012)] published Mon Mar 5, 2012.

Effects of beam temperature and density variation on the growth rate of a two-stream free electron laser

F. M. Aghamir and N. Mahdizadeh
The effect of beam temperature and density variation on the growth rate of a two-stream free electron laser (TSFEL) with planer wiggler pump has been verified. With the aid of momentum transfer, Poisson, continuity, and Maxwell's equations, the dispersion relation was derived. The eighth order dispe ... [Phys. Plasmas 19, 032114 (2012)] published Thu Mar 29, 2012.

Study of high frequency parallel propagating modes in a weakly magnetized relativistic degenerate electron plasma

Gohar Abbas, M. F. Bashir, Muddasir Ali, and G. Murtaza
Using the Vlasov-Maxwell's model, the generalized dispersion relations for parallel propagating electromagnetic modes (R- and L-waves) and electrostatic mode (Langmuir wave) for weakly magnetized relativistic degenerate plasma are derived. The propagation characteristics of these modes are analyzed ... [Phys. Plasmas 19, 032103 (2012)] published Tue Mar 6, 2012.

Breaking of Longitudinal Akhiezer-Polovin Waves

Prabal Singh Verma, Sudip Sengupta, and Predhiman Kaw
The breaking of longitudinal Akhiezer-Polovin (AP) waves is demonstrated using a one-dimensional simulation based on the Dawson sheet model. It is found that the AP longitudinal waves break through the process of phase mixing at an amplitude well below the breaking amplitude for AP waves, when subje ... [Phys. Rev. Lett. 108, 125005 ] published .

Focusing of Relativistic Electrons in Dense Plasma Using a Resistivity-Gradient-Generated Magnetic Switchyard

A. P. L Robinson, M. H. Key, and M. Tabak
A method for producing a self-generated magnetic focussing structure for a beam of laser-generated relativistic electrons using a complex array of resistivity gradients is proposed and demonstrated using numerical simulations. The array of resistivity gradients is created by using a target consistin ... [Phys. Rev. Lett. 108, 125004 ] published .

Increasing Hydrodynamic Efficiency by Reducing Cross-Beam Energy Transfer in Direct-Drive-Implosion Experiments

D. H. Froula, I. V. Igumenshchev, D. T. Michel, D. H. Edgell, R. Follett et al.
A series of experiments to determine the optimum laser-beam radius by balancing the reduction of cross-beam energy transfer (CBET) with increased illumination nonuniformities shows that the hydrodynamic efficiency is increased by ~35%, which leads to a factor of 2.6 increase in the neutron yield whe ... [Phys. Rev. Lett. 108, 125003 ] published .

Influence of Surface Waves on Plasma High-Order Harmonic Generation

Daniel an der Brugge, Naveen Kumar, Alexander Pukhov, and Christian Rodel
The influence of surface plasma waves on high-order harmonic generation from the interaction of intense lasers with overdense plasma is analyzed. It is shown that the surface waves lead to the emission of harmonics away from the optical axis, whereas the high-order on-axis harmonics are lowered in i ... [Phys. Rev. Lett. 108, 125002 ] published .

Hot Electron Temperature and Coupling Efficiency Scaling with Prepulse for Cone-Guided Fast Ignition

T. Ma, H. Sawada, P. K. Patel, C. D. Chen, L. Divol et al.
The effect of increasing prepulse energy levels on the energy spectrum and coupling into forward-going electrons is evaluated in a cone-guided fast-ignition relevant geometry using cone-wire targets irradiated with a high intensity (10 W/cm) laser pulse. Hot electron temperature and flux are inferr ... [Phys. Rev. Lett. 108, 115004 ] published .

Anticorrelation between Ion Acceleration and Nonlinear Coherent Structures from Laser-Underdense Plasma Interaction

F. Sylla, A. Flacco, S. Kahaly, M. Veltcheva, A. Lifschitz et al.
In laser-plasma experiments, we observed that ion acceleration from the Coulomb explosion of the plasma channel bored by the laser is prevented when multiple plasma instabilities, such as filamentation and hosing, and nonlinear coherent structures (vortices or postsolitons) appear in the wake of an ... [Phys. Rev. Lett. 108, 115003 ] published .

Dominance of Radiation Pressure in Ion Acceleration with Linearly Polarized Pulses at Intensities of 10 W cm

B. Qiao, S. Kar, M. Geissler, P. Gibbon, M. Zepf et al.
A novel regime is proposed where, by employing linearly polarized laser pulses at intensities 10 W cm (2 orders of magnitude lower than discussed in previous work [T. Esirkepov et al., Phys. Rev. Lett. 92, 175003 (2004)]), ions are dominantly accelerated from ultrathin foils by the radiation pressu ... [Phys. Rev. Lett. 108, 115002 ] published .

Channeling of Relativistic Laser Pulses, Surface Waves, and Electron Acceleration

N. Naseri, D. Pesme, W. Rozmus, and K. Popov
The interaction of a high-energy relativistic laser pulse with an underdense plasma is studied by means of 3-dimensional particle in cell simulations and theoretical analysis. For powers above the threshold for channeling, the laser pulse propagates as a single mode in an electron-free channel durin ... [Phys. Rev. Lett. 108, 105001 ] published .

Determination of carrier-envelope phase of relativistic few-cycle laser pulses by Thomson backscattering spectroscopy

M. Wen (温猛), L. L. Jin (金璐玲), H. Y. Wang (王鸿勇), Z. Wang (王智), B. F. Shen (沈百飞) et al.
A method is proposed to determine the carrier-envelope phase (CEP) of a relativistic few-cycle laser pulse via the frequency of the Thomson backscattering (TBS) light. We theoretically investigate the generation of a flying mirror when a few-cycle drive pulse with relativistic intensity interacts wi ... [Phys. Rev. E 85, 035401 ] published .

Stimulated Raman scattering from ice-VIII by shock-induced compression in liquid water

Zhiwei Men, Zuowei Li, Mi Zhou, Guohui Lu, Bo Zou et al.
Stimulated Raman scattering (SRS) from ice-VIII was investigated using shock-induced compression (SIC) generated by laser-induced breakdown in liquid water. Three backward SRS peaks of OH stretching vibrations and one backward SRS characteristic peak of lattice translation were observed. The SRS spe ... [Phys. Rev. B 85, 092101 ] published .

Precision linac and laser technologies for nuclear photonics gamma-ray sources

F. Albert, F. V. Hartemann, S. G. Anderson, R. R. Cross, D. J. Gibson et al.
Tunable, high precision gamma-ray sources are under development to enable nuclear photonics, an emerging field of research. This paper focuses on the technological and theoretical challenges related to precision Compton scattering gamma-ray sources. In this scheme, incident laser photons are scatter ... [Phys. Plasmas 19, 056701 (2012)] published Fri Mar 30, 2012.

Characterizing counter-streaming interpenetrating plasmas relevant to astrophysical collisionless shocks

J. S. Ross, S. H. Glenzer, P. Amendt, R. Berger, L. Divol et al.
A series of Omega experiments have produced and characterized high velocity counter-streaming plasma flows relevant for the creation of collisionless shocks. Single and double CH foils have been irradiated with a laser intensity of ~ 10 W/cm. The laser ablated plasma was characterized 4 mm from the ... [Phys. Plasmas 19, 056501 (2012)] published Wed Mar 21, 2012.

Hot-spot mix in ignition-scale implosions on the NIF

S. P. Regan, R. Epstein, B. A. Hammel, L. J. Suter, J. Ralph et al.
Ignition of an inertial confinement fusion (ICF) target depends on the formation of a central hot spot with sufficient temperature and areal density. Radiative and conductive losses from the hot spot can be enhanced by hydrodynamic instabilities. The concentric spherical layers of current National I ... [Phys. Plasmas 19, 056307 (2012)] published Fri Mar 30, 2012.

The velocity campaign for ignition on NIF

D. A. Callahan, N. B. Meezan, S. H. Glenzer, A. J. MacKinnon, L. R. Benedetti et al.
Achieving inertial confinement fusion ignition requires a symmetric, high velocity implosion. Experiments show that we can reach 95 5% of the required velocity by using a 420 TW, 1.6 MJ laser pulse. In addition, experiments with a depleted uranium hohlraum show an increase in capsule performance wh ... [Phys. Plasmas 19, 056305 (2012)] published Wed Mar 28, 2012.

Trapping induced nonlinear behavior of backward stimulated Raman scattering in multi-speckled laser beams

L. Yin, B. J. Albright, H. A. Rose, K. J. Bowers, B. Bergen et al.
In inertial confinement fusion experiments, stimulated Raman scattering (SRS) occurs when electron density fluctuations are amplified resonantly by the incident laser beams and scattered light. These beams comprise several thousands of individual laser speckles. We have found in single-speckle studi ... [Phys. Plasmas 19, 056304 (2012)] published Mon Mar 26, 2012.

Nonlinear kinetic modeling of stimulated Raman scattering in a multidimensional geometry

D. Benisti, O. Morice, L. Gremillet, A. Friou, and E. Lefebvre
In this paper, we derive coupled envelope equations modeling the growth of stimulated Raman scattering (SRS) in a multi-dimensional geometry and accounting for nonlinear kinetic effects. In particular, our envelope equations allow for the nonlinear reduction of the Landau damping rate, whose decreas ... [Phys. Plasmas 19, 056301 (2012)] published Mon Mar 19, 2012.

Inverse bremsstrahlung heating rate in atomic clusters irradiated by femtosecond laser pulses

M. Moll, Th. Bornath, M. Schlanges, and V. P. Krainov
In the interaction of atomic clusters with femtosecond laser pulses, nanoplasmas with high density and high temperature are created. The heating is mainly determined by inverse bremsstrahlung (IB) due to electron-ion collisions. In many approaches for the calculation of the IB heating rate such as t ... [Phys. Plasmas 19, 033303 (2012)] published Wed Mar 28, 2012.

Induced chirp in laser wake-field generation

Meisam Taghipour, Saeed Mirzanejhad, Farshad Sohbarzadeh, and Mehdi Asri
Particle-in-cell simulation is used to illustrate induced chirp in the laser wake-field generation experiment. The evolution of the laser pulse characteristics and the wake-field amplitude is investigated numerically. The local frequency of the laser pulse is influenced during wake-field excitation. ... [Phys. Scr. 85, 035505 (2012)] published Tue Mar 6, 2012.

Electron injection and acceleration in the plasma bubble regime driven by an ultraintense laser pulse combined with using dense-plasma wall and block

Xue-Yan Zhao, Bai-Song Xie, Hai-Cheng Wu, Shan Zhang, Xue-Ren Hong et al.
An optimizing and alternative scheme for electron injection and acceleration in the wake bubble driven by an ultraintense laser pulse is presented. In this scheme, the dense-plasma wall with an inner diameter matching the expected bubble size is placed along laser propagation direction. Meanwhile, a ... [Phys. Plasmas 19, 033108 (2012)] published Thu Mar 29, 2012.

Long-Range Persistence of Femtosecond Modulations on Laser-Plasma-Accelerated Electron Beams

C. Lin, J. van Tilborg, K. Nakamura, A. J. Gonsalves, N. H. Matlis et al.
Laser plasma accelerators have produced femtosecond electron bunches with a relative energy spread ranging from 100% to a few percent. Simulations indicate that the measured energy spread can be dominated by a correlated spread, with the slice spread significantly lower. Measurements of coherent opt ... [Phys. Rev. Lett. 108, 094801 ] published .

Surface-plasmon-enhanced MeV ions from femtosecond laser irradiated, periodically modulated surfaces

Suman Bagchi, P. Prem Kiran, W.-M. Wang, Z. M. Sheng, M. K. Bhuyan et al.
Enhanced emission of high energy ions is measured from sub-wavelength metallic grating targets under irradiation by intense (1010 W cm), p-polarized, 50 fs, 800 nm laser pulses. The maximum ion energy is 55% higher and the ion flux is 60% higher for the modulated surface in comparison with polished ... [Phys. Plasmas 19, 030703 (2012)] published Fri Mar 16, 2012.

Extreme supercontinuum generation to the deep UV

S. P. Stark, J. C. Travers, and P. St. J. Russell
We report the formation of an ultrabroad supercontinuum down to 280 nm in the deep UV by pumping sharply tapered (530 mm taper lengths) solid-core photonic crystal fibers with 130 fs, 2 nJ pulses at 800 nm. The taper moves the point of soliton fission to a position where the core is narrower, a proc ... [Opt. Lett. 37, 770 (2012)] published Thu Mar 1, 2012.

Ultrashort superradiant pulse generation from a GaN/InGaN heterostructure

V. F. Olle, P. P. Vasil'ev, A. Wonfor, R. V. Penty, and I. H. White
Dicke superradiance from a two-section violet GaN/InGaN semiconductor laser diode is demonstrated for the first time. In the superradiance regime, optical pulses with peak powers in excess of 2.8 W and durations as short as 1.4 ps are generated at repetition rates of up to 10 MHz at the emission wav ... [Opt. Express 20, 7035 (2012)] published Thu Mar 29, 2012.

Numerical analysis of aperiodic photonic crystal fiber structures for supercontinuum generation

Annalisa Di Tommaso, Marco De Sario, Luciano Mescia, and Francesco Prudenzano
An unconventional photonic crystal fiber (PCF) is designed in order to obtain supercontinuum (SC) generation. The distance of the air hole rings is not constant, but it follows the Thue-Morse (ThMo) aperiodic sequence. The spectral broadening of high power femtosecond (fs) input pulses in anomalous ... [Opt. Eng. 51, 035003 (2012)] published Tue Mar 13, 2012.

Improved NRZ transmission distance at 20 Gbit/s using dual electroabsorption modulated laser

K. Kechaou, T. Anfray, K. Merghem, C. Aupetit-Berthelemot, G. Aubin et al.
An error-free 39.7 km transmission for a 20 Gbit/s NRZ signal in standard dispersion fibre without dispersion compensation is carried out both experimentally and by simulation using the dual electroabsorption modulated laser (D-EML). The D-EML comprises an integrated electroabsorption modulated lase ... [Electron. Lett. 48, 335 ] published .

Polarization Properties of Deep-Ultraviolet Optical Gain in Al-Rich AlGaN Structures

Emanuele Francesco Pecora, Wei Zhang, Jian Yin, Roberto Paiella, Luca Dal Negro et al.
The polarization properties of the amplified spontaneous emission (ASE) in the deep-UV wavelengths from AlGaN/AlN structures with 70% Al content have been investigated. Samples are prepared through a novel liquid phase epitaxy mode leading to strong compositional fluctuations. Large net modal gain i ... [Appl. Phys. Express 5, 032103 (2012)] published Thu Mar 15, 2012.

Gold nanoparticles on the surface of soda-lime glass: morphological, linear and nonlinear optical characterization

E. C. Romani, Douglas Vitoreti, Paula M. P. Gouvea, P. G. Caldas, R. Prioli et al.
Materials presenting high optical nonlinearity, such as materials containing metal nanoparticles (NPs), can be used in various applications in photonics. This motivated the research presented in this paper, where morphological, linear and nonlinear optical characteristics of gold NPs on the surface ... [Opt. Express 20, 5429 (2012)] published Thu Mar 15, 2012.

Ultrafast Quantum Gates in Circuit QED

G. Romero, D. Ballester, Y. M. Wang, V. Scarani, and E. Solano
We present a method to implement ultrafast two-qubit gates valid for the ultrastrong coupling and deep strong coupling regimes of light-matter interaction, considering state-of-the-art circuit quantum electrodynamics technology. Our proposal includes a suitable qubit architecture and is based on a f ... [Phys. Rev. Lett. 108, 120501 ] published .

Tunable ultrafast nonlinear optofluidic coupler

Marius Vieweg, Sebastian Pricking, Timo Gissibl, Yaroslav V. Kartashov, Lluis Torner et al.
We present an optofluidic nonlinear coupler fabricated by selective filling of two strands of a photonic crystal fiber with the liquid CCl which exhibits a large ultrafast Kerr nonlinearity. We demonstrate power dependent switching in this novel optofluidic device. The large thermo-optical effect of ... [Opt. Lett. 37, 1058 (2012)] published Thu Mar 29, 2012.

Nonlinearly generated harmonic signals in ultra-small waveguides with magnetic films: Tunable enhancements of 2nd and 4th harmonics

J. Marsh, V. Zagorodnii, Z. Celinski, and R. E. Camley
The nonlinear generation of high harmonic signals (up to 5th harmonic) is explored in an ultra-small waveguide which contains a thin ferromagnetic film. The strength of the different harmonics is highly tunable. In particular, the power in the 2nd and 4th harmonic signals may be enhanced by over two ... [Appl. Phys. Lett. 100, 102404 (2012)] published Thu Mar 8, 2012.

Prism-coupled surface wave accelerator based on silicon carbide

Burton Neuner, III, Dmitriy Korobkin, Gabriel Ferro, and Gennady Shvets
A compact, solid-state accelerating structure based on surface waves is proposed and experimentally characterized. The structure, consisting of two SiC layers epitaxially grown on Si slabs and separated from each other by a subwavelength acceleration channel, is shown to support both longitudinal (a ... [Phys. Rev. ST Accel. Beams 15, 031302 ] published .

Ultrafast Photon-Photon Interaction in a Strongly Coupled Quantum Dot-Cavity System

Dirk Englund, Arka Majumdar, Michal Bajcsy, Andrei Faraon, Pierre Petroff et al.
We study dynamics of the interaction between two weak light beams mediated by a strongly coupled quantum dotphotonic crystal cavity system. First, we perform all-optical switching of a weak continuous-wave signal with a pulsed control beam, and then perform switching between two weak pulsed beams (4 ... [Phys. Rev. Lett. 108, 093604 ] published .

Generation of Elliptically Polarized Terahertz Waves from Laser-Induced Plasma with Double Helix Electrodes

Xiaofei Lu and X.-C. Zhang
By applying a helical electric field along a plasma region, a revolving electron current is formed along the plasma and an elliptically polarized far-field terahertz wave pattern is observed. The observed terahertz wave polarization reveals the remarkable role of velocity retardation between optical ... [Phys. Rev. Lett. 108, 123903 ] published .

Role of interband and photoinduced absorption in the nonlinear refraction and absorption of resonantly excited PbS quantum dots around 1550 nm

Abdoulghafar Omari, Iwan Moreels, Francesco Masia, Wolfgang Langbein, Paola Borri et al.
The nonlinear refractive index n and absorption coefficient beta of PbS quantum dots (Qdots) is determined around 1550 nm with the Z-scan technique, using a picosecond pulsed laser. We find that n is wavelength tunable and follows the PbS absorbance spectrum. At fixed wavelength, n is constant in th ... [Phys. Rev. B 85, 115318 ] published .

Theoretical investigation of the inverse Faraday effect via a stimulated Raman scattering process

Daria Popova, Andreas Bringer, and Stefan Blugel
We study theoretically the origin and mechanism of the ultrafast inverse Faraday effect, which is a magneto-optical effect, attracting much interest nowadays. Laser-induced subpicosecond spin dynamics in hydrogenlike systems and isolated many-electron atoms are investigated in order to get insight i ... [Phys. Rev. B 85, 094419 ] published .

Forster-mediated spectral diffusion in disordered organic materials

Franziska Fennel and Stefan Lochbrunner
A model that describes exciton diffusion in disordered organic materials is introduced that is capable of quantitatively describing the effects of inhomogeneous broadening and energetic disorder on the energy transfer. The model is tested on a system that consists of a polymer matrix containing the ... [Phys. Rev. B 85, 094203 ] published .

Influence of acoustic phonons on the optical control of quantum dots driven by adiabatic rapid passage

S. Luker, K. Gawarecki, D. E. Reiter, A. Grodecka-Grad, V. M. Axt et al.
The role of phonons for adiabatic rapid passage in semiconductor quantum dots is studied theoretically. While in an ideal system adiabatic rapid passage results in a full inversion of the quantum dot occupation, phonons hamper this behavior drastically. We show that the transitions between the adiab ... [Phys. Rev. B 85, 121302 ] published .

Nonlinear light-matter interaction with femtosecond high-angle Bessel beams

D. Faccio, E. Rubino, A. Lotti, A. Couairon, A. Dubietis et al.
We show that high-angle Bessel beams may significantly reduce nonlinear pulse distortions due, for example, to nonlinear Kerr effects (self-phase-modulation and self-focusing) yet enhance ionization and plasma generation. Holographic reconstruction of Bessel beams in water show intensity clamping at ... [Phys. Rev. A 85, 033829 ] published .

Intrapulse quantum spectral correlation of femtosecond optical pulses in optical fiber

Heongkyu Ju
Intrapulse quantum spectral correlation of photon numbers of a femtosecond optical pulse, which propagates a 5-m-long optical fiber, is presented in a matrix format for quantum noise study by numerical calculation. The calculation includes the higher-order optical effects such as intrapulse-stimulat ... [Phys. Rev. A 85, 033810 ] published .

Fixed-point attractor for chirp in nonlinear waveguide arrays

Darren D. Hudson, J. Nathan Kutz, Thomas R. Schibli, Qing Chao, Demetrios N. Christodoulides et al.
The propagation of ultrashort optical pulses in an AlGaAs waveguide array is studied using frequency-resolved optical gating measurements. In the nonlinear regime, the measurements show that the pulses at the output of the array evolve toward a set chirp value that is independent of the input chirp. ... [Phys. Rev. A 85, 031806 ] published .

Ultrafast, high resolution, phase contrast imaging of impact response with synchrotron radiation

B. J. Jensen, S. N. Luo, D. E. Hooks, K. Fezzaa, K. J. Ramos et al.
Understanding the dynamic response of materials at extreme conditions requires diagnostics that can provide real-time, in situ, spatially resolved measurements on the nanosecond timescale. The development of methods such as phase contrast imaging (PCI) typically used at synchrotron sources offer uni ... [AIP Advances 2, 012170 (2012)] published Fri Mar 9, 2012.

A weakly coupled semiconductor superlattice as a potential for a radio frequency modulated terahertz light emitter

G. K. Rasulova, P. N. Brunkov, I. V. Pentin, A. Yu. Egorov, D. A. Knyazev et al.
The bolometer response to THz radiation from a weakly coupled GaAs/AlGaAs superlattice biased in the self-oscillations regime has been observed. The bolometer signal is modulated with the frequency equal to the fundamental frequency of superlattice self-oscillations. The frequency spectrum of the bo ... [Appl. Phys. Lett. 100, 131104 (2012)] published Mon Mar 26, 2012.

Measurement of light diffusion in ZnO nanowire forests

Marijn A. M. Versteegh, Ruben E. C. van der Wel, and Jaap I. Dijkhuis
Optimum design of efficient nanowire solar cells requires better understanding of light diffusion in a nanowire array. Here we demonstrate that our recently developed ultrafast all-optical shutter can be used to directly measure the dwell time of light in a nanowire array. Our measurements on disord ... [Appl. Phys. Lett. 100, 101108 (2012)] published Thu Mar 8, 2012.

Femtosecond third-order nonlinear spectra of lead-germanium oxide glasses containing silver nanoparticles

Leonardo De Boni, Emerson C. Barbano, Thiago A. de Assumpcao, Lino Misoguti, Luciana R. P. Kassab et al.
This work reports on the spectral dependence of both nonlinear refraction and absorption in lead-germanium oxide glasses (PbO-GeO) containing silver nanoparticles. We have found that this material is suitable for all-optical switching at telecom wavelengths but at the visible range it behaves either ... [Opt. Express 20, 6844 (2012)] published Thu Mar 15, 2012.

Experimental observation of electronhole recollisions

B. Zaks, R. B. Liu, and M. S. Sherwin
An intense laser field can remove an electron from an atom or molecule and pull the electron into a large-amplitude oscillation in which it repeatedly collides with the charged core it left behind. Such recollisions result in the emission of very energetic photons by means of high-order-harmonic ge ... [Nature 483, 580 (2012)] published Thu Mar 29, 2012.

Characterization of supercooled liquid GeSbTe and its crystallization by ultrafast-heating calorimetry

J. Orava, A. L. Greer, B. Gholipour, D. W. Hewak, and C. E. Smith
Differential scanning calorimetry (DSC) is widely used to study the stability of amorphous solids, characterizing the kinetics of crystallization close to the glass-transition temperature T. We apply ultrafast DSC to the phase-change material GeSbTe (GST) and show that if the range of heating rates ... [Nature Mater. 11, 279 (2012)] published Thu Mar 22, 2012.

Field-driven photoemission from nanostructures quenches the quiver motion

G. Herink, D. R. Solli, M. Gulde, and C. Ropers
Strong-field physics, an extreme limit of lightmatter interaction, is expanding into the realm of surfaces and nanostructures from its origin in atomic and molecular science. The attraction of nanostructures lies in two intimately connected features: local intensity enhancement and sub-wavelength c ... [Nature 483, 190 (2012)] published Thu Mar 8, 2012.

Solitons in highly nonlocal nematic liquid crystals: Variational approach

Najdan B. Aleksic, Milan S. Petrovic, Aleksandra I. Strinic, and Milivoj R. Belic
We investigate numerically and theoretically solitons in highly nonlocal three-dimensional nematic liquid crystals. We calculate the fundamental soliton profiles using the modified Petviashvili method. We apply the variational method to the widely accepted scalar model of beam propagation in uniaxia ... [Phys. Rev. A 85, 033826 ] published .

Local structures in ionic liquids probed and characterized by microscopic thermal diffusion monitored with picosecond time-resolved Raman spectroscopy

Kyousuke Yoshida, Koichi Iwata, Yoshio Nishiyama, Yoshifumi Kimura, and Hiro-o Hamaguchi
Vibrational cooling rate of the first excited singlet (S) state of trans-stilbene and bulk thermal diffusivity are measured for seven room temperature ionic liquids, CmimTfN, CmimTfN, CmimPF, CmimTfN, CmimTfN, CmimTfN, and bmpyTfN. Vibrational cooling rate measured with picosecond time-resolved Rama ... [J. Chem. Phys. 136, 104504 (2012)] published Thu Mar 8, 2012.

Ultrafast Strain Engineering in Complex Oxide Heterostructures

A. D. Caviglia, R. Scherwitzl, P. Popovich, W. Hu, H. Bromberger et al.
We report on ultrafast optical experiments in which femtosecond midinfrared radiation is used to excite the lattice of complex oxide heterostructures. By tuning the excitation energy to a vibrational mode of the substrate, a long-lived five-order-of-magnitude increase of the electrical conductivity ... [Phys. Rev. Lett. 108, 136801 ] published .

Plasmon Scattering from Single Subwavelength Holes

N. Rotenberg, M. Spasenovic, T. L. Krijger, B. le Feber, F. J. Garcia de Abajo et al.
We map the complex electric fields associated with the scattering of surface plasmon polaritons by single subwavelength holes of different sizes in thick gold films. We identify and quantify the different modes associated with this event, including a radial surface wave with an angularly isotropic a ... [Phys. Rev. Lett. 108, 127402 ] published .

Role of Magnetic Circular Dichroism in All-Optical Magnetic Recording

A. R. Khorsand, M. Savoini, A. Kirilyuk, A. V. Kimel, A. Tsukamoto et al.
Using magneto-optical microscopy in combination with ellipsometry measurements, we show that all-optical switching with polarized femtosecond laser pulses in ferrimagnetic GdFeCo is subjected to a threshold fluence absorbed in the magnetic layer, independent of either the excitation wavelength or th ... [Phys. Rev. Lett. 108, 127205 ] published .

Ultrafast Optical Excitation of a Persistent Surface-State Population in the Topological Insulator BiSe

J. A. Sobota, S. Yang, J. G. Analytis, Y. L. Chen, I. R. Fisher et al.
Using femtosecond time- and angle-resolved photoemission spectroscopy, we investigated the nonequilibrium dynamics of the topological insulator BiSe. We studied p-type BiSe, in which the metallic Dirac surface state and bulk conduction bands are unoccupied. Optical excitation leads to a metastable p ... [Phys. Rev. Lett. 108, 117403 ] published .

Dynamics of photoexcited carriers in graphene

B. Y. Sun, Y. Zhou, and M. W. Wu
The nonequilibrium dynamics of carriers and phonons in graphene is investigated by solving the microscopic kinetic equations with the carrier-phonon and carrier-carrier Coulomb scatterings explicitly included. The Fermi distribution of hot carriers is found to be established within 100 fs and the te ... [Phys. Rev. B 85, 125413 ] published .

Time-resolved differential transmission in MOVPE-grown ferromagnetic InMnAs

M. Bhowmick, T. R. Merritt, G. A. Khodaparast, Bruce W. Wessels, Stephen A. McGill et al.
We measured time-resolved differential transmission in InMnAs for different pump/probe schemes as a function of temperature, laser fluence, and external magnetic field. We observed tunability of the carrier relaxation time. In addition, we found that the sign of the differential transmission changed ... [Phys. Rev. B 85, 125313 ] published .

Influence of electronic coupling on the radiative lifetime in the (In,Ga)As/GaAs quantum dotquantum well system

M. Syperek, J. Andrzejewski, W. Rudno-Rudzinski, G. Sek, J. Misiewicz et al.
In this paper, we present time-resolved photoluminescence of self-assembled (In,Ga)As quantum dots (QDs) coupled to an InGaAs quantum well (QW) through a thin GaAs barrier. The coupling strength is controlled by the well width and material composition and has a direct influence on the QDQW system gr ... [Phys. Rev. B 85, 125311 ] published .

Dimerization-induced spin-charge coupling in one-dimensional Mott insulators revealed by femtosecond reflection spectroscopy of Rb-tetracyanoquinodimethane salts

H. Uemura, N. Maeshima, K. Yonemitsu, and H. Okamoto
Effects of lattice dimerizations on charge dynamics in one-dimensional (1D) half-filled Mott insulators were studied using an organic compound, Rb-tetracyanoquinodimethane (TCNQ). First, we investigated the presence of the dimeric molecular displacements by the measurements of polarized Raman spectr ... [Phys. Rev. B 85, 125112 ] published .

Second harmonic generation in multilayer graphene induced by direct electric current

Anton Y. Bykov, Tatiana V. Murzina, Maxim G. Rybin, and Elena D. Obraztsova
Optical second harmonic generation (SHG) is studied from multilayer graphene films in the presence of dc electric current flowing in the sample plane. Graphene layers are manufactured by the chemical vapor deposition technique and deposited on an oxidized Si(001) substrate. SHG intensity from the gr ... [Phys. Rev. B 85, 121413 ] published .

Spin dephasing of fluorine-bound electrons in ZnSe

A. Greilich, A. Pawlis, F. Liu, O. A. Yugov, D. R. Yakovlev et al.
The spin coherence of an ensemble of electrons bound to fluorine donors in epitaxially grown ZnSe layers is studied by time-resolved pump-probe Kerr rotation. Long-lived spin dephasing with decay times up to T=33 ns is found for a sample with a low fluorine concentration of 1 x 10 cm at cryogenic te ... [Phys. Rev. B 85, 121303 ] published .

Optically controlled phase gate for two spin qubits in coupled quantum dots

Li-Bo Chen, L. J. Sham, and Edo Waks
We present a feasible scheme for performing an optically controlled phase gate between two conduction electron spin qubits in adjacent self-assembled quantum dots. Interaction between the dots is mediated by the tunneling of the valence hole state, which is activated only by applying a laser pulse o ... [Phys. Rev. B 85, 115319 ] published .

All-optical magnetization reversal by circularly polarized laser pulses: Experiment and multiscale modeling

K. Vahaplar, A. M. Kalashnikova, A. V. Kimel, S. Gerlach, D. Hinzke et al.
We present results of detailed experimental and theoretical studies of all-optical magnetization reversal by single circularly-polarized laser pulses in ferrimagnetic rare earthtransition metal (RETM) alloys GdFeCo (20%

Attenuation of propagating spin wave induced by layered nanostructures

K. Sekiguchi, T. N. Vader, K. Yamada, S. Fukami, N. Ishiwata et al.
Spin wave attenuation in the layered [FeNi/Pt]/FeNi thin films was investigated by the time-domain electrical measurement. The spin-wave waveform was detected with an asymmetric coplanar strip transmission line, as an induced voltage flowing into a fast oscilloscope. We report that the amplitude of ... [Appl. Phys. Lett. 100, 132411 (2012)] published Fri Mar 30, 2012.

Electron-nuclei spin coupling in GaAsFree versus localized electrons

J. Huang, Y. S. Chen, A. Ludwig, D. Reuter, A. D. Wieck et al.
We report on an experimental evidence of a significantly different dynamic nuclear polarization (DNP) for localized and itinerant electrons in n-GaAs. Optically injected spin-polarized electrons are used to generate dynamic nuclear polarization via electron-nucleus hyperfine interaction. Using time ... [Appl. Phys. Lett. 100, 132103 (2012)] published Tue Mar 27, 2012.

Time-resolved measurements of field-driven domain wall motion in a submicron strip with perpendicular magnetic anisotropy

Satoru Emori, David C. Bono, and Geoffrey S. D. Beach
The motion of domain walls (DWs), driven by magnetic field and spanning almost eight orders of magnitude in velocity, has been studied in a submicron-wide strip of Co/Pt with perpendicular magnetic anisotropy. A scanning magneto-optic Kerr effect (MOKE) system is used to conduct time-resolved measur ... [J. Appl. Phys. 111, 07D304 (2012)] published Mon Mar 5, 2012.

Precessional spin-transfer switching in a magnetic tunnel junction with a synthetic antiferromagnetic perpendicular polarizer

M. Marins de Castro, R. C. Sousa, S. Bandiera, C. Ducruet, A. Chavent et al.
This paper reports sub-nanosecond precessional spin-transfer switching in elliptical magnetic tunnel junction nanopillars. This result is obtained in samples integrating a synthetic antiferromagnetic perpendicular polarizer and a tunnel junction with in-plane magnetized electrodes. The out-of-plane ... [J. Appl. Phys. 111, 07C912 (2012)] published Wed Mar 7, 2012.

Electron-phonon scattering dynamics in ferromagnets on ultrafast timescales: Influence of the phonon temperature

Sven Essert and Hans Christian Schneider
The magnetization response of bulk ferromagnets after excitation by an ultrashort optical pulse is calculated using a dynamical model of the Elliott-Yafet type that includes the effects of the spin-orbit interaction in the ab-initio ferromagnetic band structure, the electron-phonon interaction at th ... [J. Appl. Phys. 111, 07C514 (2012)] published Wed Mar 7, 2012.

Frequency tuning the ultrafast magnetization dynamics of FePt alloys

R. Brandt, F. Ganss, T. Senn, M. Daniel, M. Albrecht et al.
We report frequency tuning of magnetic oscillations in both planar films and individual patterned nano-sized dots by varying the iron content of disordered FePt alloys from 42 at. % to 100 at. %. It is seen that as the Fe content is increased, the magnetic oscillation frequency rises by up to 50% in ... [J. Appl. Phys. 111, 053918 (2012)] published Wed Mar 7, 2012.

Temperature dependence of electron-spin relaxation in a single InAs quantum dot at zero applied magnetic field

X. M. Dou, B. Q. Sun, D. S. Jiang, H. Q. Ni, and Z. C. Niu
The temperature-dependent electron spin relaxation of positively charged excitons in a single InAs quantum dot was measured by time-resolved photoluminescence spectroscopy at zero applied magnetic fields. The experimental results show that the electron-spin relaxation is clearly divided into two dif ... [J. Appl. Phys. 111, 053524 (2012)] published Thu Mar 8, 2012.

Thermoplastic deformation of silicon surfaces induced by ultrashort pulsed lasers in submelting conditions

G. D. Tsibidis, E. Stratakis, and K. E. Aifantis
A hybrid theoretical model is presented to describe thermoplastic deformation effects on silicon surfaces induced by single and multiple ultrashort pulsed laser irradiation in submelting conditions. An approximation of the Boltzmann transport equation is adopted to describe the laser irradiation pro ... [J. Appl. Phys. 111, 053502 (2012)] published Thu Mar 1, 2012.

Two-photon-pumped optical gain in dye-polymer composite materials

Wei Li, Chunfeng Zhang, Qi Chen, Xiaoyong Wang, and Min Xiao
Optical gain with two-photon pumping has been quantitatively characterized in the energy-transfer-coupled dye-polymer composite materials. Using femtosecond transient absorption spectroscopy, we observed frequency up-converted optical amplification in the dye-doped polymer films. Net optical gain co ... [Appl. Phys. Lett. 100, 133305 (2012)] published Tue Mar 27, 2012.

Carrier dynamics and conductivity of SnO nanowires investigated by time-resolved terahertz spectroscopy

Demetra Tsokkou, Andreas Othonos, and Matthew Zervos
THz spectroscopy has been applied to investigate the photo-induced and intrinsic conductivity in SnO nanowires using the Drude-Smith model. The refractive index of the nanowires was found to decrease from 2.4 to 2.1 with increasing THz frequency and the dc mobility of the non-excited nanowires was d ... [Appl. Phys. Lett. 100, 133101 (2012)] published Mon Mar 26, 2012.

Visualizing charge movement near organic heterojunctions with ultrafast time resolution via an induced Stark shift

Gary P. Wiederrecht, Noel C. Giebink, Jasmina Hranisavljevic, Daniel Rosenmann, Alex B. F. Martinson et al.
We introduce a method to monitor photoinduced charge separation processes in organic donor-acceptor heterostructures. This approach utilizes a transient Stark shift of the exciton band of a molecular J-aggregate, deposited as a thin probe layer adjacent to the organic heterojunction. The high tempor ... [Appl. Phys. Lett. 100, 113304 (2012)] published Thu Mar 15, 2012.

Site-selective photoluminescence in thiol-capped gold nanoclusters

T. N. Lin, C. H. Liu, G. W. Shu, J. L. Shen, C. A. J. Lin et al.
Photoluminescence (PL) from the thiol-capped Au nonoclusters (NCs) has been investigated under site-selective excitation. Upon scanning the excitation light with energy below 2.1 eV down to 1.6 eV, the PL narrows and begins shifting linearly with excitation energy. The time-resolved PL was studied a ... [Appl. Phys. Lett. 100, 103102 (2012)] published Mon Mar 5, 2012.

Control of coherent acoustic phonon generation with external bias in InGaN/GaN multiple quantum wells

C. S. Kim, J. H. Kim, H. Jeong, Y. D. Jho, H. K. Kwon et al.
Control of acoustic phonon generation with external bias is demonstrated for an InGaN light-emitting diode by performing femtosecond pumpprobe measurements. The evolution of both the carrier dynamics and the acoustic phonon strength with an external bias reveals that the acoustic wave is generated d ... [Appl. Phys. Lett. 100, 101105 (2012)] published Tue Mar 6, 2012.

Creation of particle-hole superposition states in graphene at multiphoton resonant excitation by laser radiation

H. K. Avetissian, A. K. Avetissian, G. F. Mkrtchian, and Kh. V. Sedrakian
Nonlinear dynamics of the establishment of electron-hole coherent superposition states in graphene by multiphoton resonant excitation of interband transitions in laser fields is considered. The single-particle time-dependent density matrix for such a quantized system is calculated in the multiphoton ... [Phys. Rev. B 85, 115443 ] published .

Ferroelectric Soft Mode in a SrTiO Thin Film Impulsively Driven to the Anharmonic Regime Using Intense Picosecond Terahertz Pulses

I. Katayama, H. Aoki, J. Takeda, H. Shimosato, M. Ashida et al.
The ferroelectric soft mode in a SrTiO thin film was impulsively driven to a large amplitude using intense picosecond terahertz pulses. As the terahertz electric field increased, the soft-mode absorption peak exhibited blueshifting and spectral narrowing. A classical anharmonic oscillator model sugg ... [Phys. Rev. Lett. 108, 097401 ] published .

Ultrafast Momentum-Dependent Response of Electrons in Antiferromagnetic EuFeAs Driven by Optical Excitation

L. Rettig, R. Cortes, S. Thirupathaiah, P. Gegenwart, H. S. Jeevan et al.
Employing the momentum sensitivity of time- and angle-resolved photoemission spectroscopy we demonstrate the analysis of ultrafast single- and many-particle dynamics in antiferromagnetic EuFeAs. Their separation is based on a temperature-dependent difference of photoexcited hole and electron relaxat ... [Phys. Rev. Lett. 108, 097002 ] published .

Detecting optically synthesized quasi-monochromatic sub-terahertz phonon wavepackets by ultrafast x-ray diffraction

M. Herzog, A. Bojahr, J. Goldshteyn, W. Leitenberger, I. Vrejoiu et al.
We excite an epitaxial SrRuO thin film transducer by a pulse train of ultrashort laser pulses, launching coherent sound waves into the underlying SrTiO substrate. Synchrotron-based x-ray diffraction (XRD) data exhibiting separated sidebands to the substrate peak evidence the excitation of a quasi-mo ... [Appl. Phys. Lett. 100, 094101 (2012)] published Mon Feb 27, 2012.

Exciton spin relaxation in InGaAs/AlAsSb quantum wells

K. Sasayama, S. Nakanishi, R. Yamaguchi, Y. Oyanagi, T. Ushimi et al.
The spin relaxation process of InGaAs/AlAsSb quantum wells is investigated by spin-dependent pump and probe reflectance measurements with a high time resolution of 200 fs. The observed spin relaxation time of 17.5 ps at 20 K indicates high potential for applications to high-speed optical devices. A ... [Appl. Phys. Lett. 100, 092401 (2012)] published Wed Feb 29, 2012.

Excitonic diffusion dynamics in ZnO

H. Jeong, K. Min, S. Byun, C. J. Stanton, D. H. Reitze et al.
We investigate excitonic carrier diffusion in both bulk ZnO and nanorods (NRs). Using time-resolved differential reflectivity spectroscopy, we observe a fast decaying component together with a longer exponential relaxation. In bulk ZnO, we find that the fast decay term (~1 ps) originates from excito ... [Appl. Phys. Lett. 100, 092106 (2012)] published Wed Feb 29, 2012.

Vibrational modes of GaAs hexagonal nanopillar arrays studied with ultrashort optical pulses

Hirotaka Sakuma, Motonobu Tomoda, Paul H. Otsuka, Osamu Matsuda, Oliver B. Wright et al.
We investigate the vibrational modes of a triangular array of anisotropic, hexagonal GaAs nanopillars on a GaAs substrate through ultrafast changes in optical reflectivity. By comparison with simulations, we identify GHz resonances, mode shapes, and damping. In addition, by varying the pillar diamet ... [Appl. Phys. Lett. 100, 131902 (2012)] published Mon Mar 26, 2012.

Long-lived, room-temperature electron spin coherence in colloidal CdS quantum dots

D. H. Feng, X. Li, T. Q. Jia, X. Q. Pan, Z. R. Sun et al.
Time-resolved Faraday rotation spectroscopy is used to study the electron spin coherence in colloidal CdS quantum dots. Long-lived spin coherence with dephasing time T>3ns has been found at room temperature. Spin dynamics unaffected by the faster carrier recombination suggests the spin signal coming ... [Appl. Phys. Lett. 100, 122406 (2012)] published Wed Mar 21, 2012.

Dynamics of confined water reconstructed from inelastic x-ray scattering measurements of bulk response functions

Robert H. Coridan, Nathan W. Schmidt, Ghee Hwee Lai, Peter Abbamonte, and Gerard C. L. Wong
Nanoconfined water and surface-structured water impacts a broad range of fields. For water confined between hydrophilic surfaces, measurements and simulations have shown conflicting results ranging from liquidlike to solidlike behavior, from bulklike water viscosity to viscosity orders of magnitude ... [Phys. Rev. E 85, 031501 ] published .

Improving high-order harmonic yield using wavefront-controlled ultrashort laser pulses

Stefan Eyring, Christian Kern, Michael Zurch, and Christian Spielmann
In this work we show that it is possible to increase the high-order harmonic yield when using wavefront-shaped laser beams. The investigation of the beam profile near the interaction region shows that the optimized beam is asymmetric and has a larger diameter. Thus, the optimized beam leads to a hig ... [Opt. Express 20, 5601 (2012)] published Thu Mar 15, 2012.

Imaging ultrafast molecular dynamics with laser-induced electron diffraction

Cosmin I. Blaga, Junliang Xu, Anthony D. DiChiara, Emily Sistrunk, Kaikai Zhang et al.
Establishing the structure of molecules and solids has always had an essential role in physics, chemistry and biology. The methods of choice are X-ray and electron diffraction, which are routinely used to determine atomic positions with sub-ngstrm spatial resolution. Although both methods are curre ... [Nature 483, 194 (2012)] published Thu Mar 8, 2012.

Strong chemical bond of stable He in strong linearly polarized laser fields

P. Balanarayan and Nimrod Moiseyev
The van der Waals complex of the helium dimer has a binding energy of ~10 eV and a bond distance of ~52 A. Our ab initio electronic structure calculations show that in an ac electric field of [approximate]5.614 x 10 W/cm with a high photon energy ([approximate]108 eV), stable He molecules with a bin ... [Phys. Rev. A 85, 032516 ] published .

Kramers-Kronig relations and high-order nonlinear susceptibilities

Carsten Bree, Ayhan Demircan, and Gunter Steinmeyer
As previous theoretical results recently revealed, a Kramers-Kronig transform of multiphoton absorption rates allows for a precise prediction on the dispersion of the nonlinear refractive index n in the near infrared. It was shown that this method allows reproduction of recent experimental results o ... [Phys. Rev. A 85, 033806 ] published .

Solution of the time-dependent Dirac equation for multiphoton ionization of highly charged hydrogenlike ions

Yulian V. Vanne and Alejandro Saenz
A theoretical study of the intense-field multiphoton ionization of hydrogenlike systems is performed by solving the time-dependent Dirac equation within the dipole approximation. It is shown that the velocity-gauge results agree to the ones in the length gauge only if the negative-energy states are ... [Phys. Rev. A 85, 033411 ] published .

Multiwavelength amplified harmonic emissions from carbon dioxide pumped by mid-infrared femtosecond laser pulses

Wei Chu, Bin Zeng, Jinping Yao, Huailiang Xu, Jielei Ni et al.
We demonstrate multiwavelength amplified harmonic emissions in carbon dioxide gas driven by intense mid-infrared femtosecond laser pulses. The simultaneous amplified emissions at 315, 326, 337 and 351nm from the A -X transition of CO are found to have a high gain coefficient of 4.43cm with the pol ... [EPL 97, 64004 (2012)] published Wed Mar 28, 2012.

Real-Time Observation of Interference between Atomic One-Electron and Two-Electron Excitations

Henning Geiseler, Horst Rottke, Nickolai Zhavoronkov, and Wolfgang Sandner
We present results of real-time tracking of atomic two-electron dynamics in an autoionizing transient wave packet in krypton. A coherent superposition of two Fano resonances is excited with a femtosecond extreme-ultraviolet pulse. The evolution of the corresponding wave packet is subsequently probed ... [Phys. Rev. Lett. 108, 123601 ] published .

Preparation and probing of coherent vibrational wave packets in the ground electronic state of HD

Rangana Bhattacharya, Souvik Chatterjee, and S. S. Bhattacharyya
We have investigated the formation of coherent vibrational wave packets in the ground electronic state of HD on exposure to intense ultrashort laser pulses of wavelength 1060 nm. The effects of the duration and field strength of the pulse on the final composition of the residual bound nuclear wave p ... [Phys. Rev. A 85, 033424 ] published .

Mapping electron dynamics in molecular H using high-order-harmonic-generation time profiles

Behnaz Buzari, Mohsen Vafaee, and Hassan Sabzyan
The mechanism of the formation of doorway quasistates (transient species) prior to the start of ionization of the two-electron molecular H system subjected to an eight-cycle ultrashort intense laser pulse is investigated by solving exactly the one-dimensional (1D) electronic time-dependent Schroding ... [Phys. Rev. A 85, 033407 ] published .

Measurement of field-free alignment of jet-cooled molecules by nonresonant femtosecond degenerate four-wave mixing

Xiaoming Ren, Varun Makhija, and Vinod Kumarappan
A femtosecond degenerate four-wave mixing (fs-DFWM) technique for probing the alignment of molecules is described. The rotational wave packet generated by a strong pump beam modulates the nonresonant third-order susceptibility of the gas and this modulation is observed using a noncollinear backgroun ... [Phys. Rev. A 85, 033405 ] published .

Phase-matching mechanism for high-photon-energy harmonics of a long trajectory driven by a midinfrared laser

Cheng Gong, Jiaming Jiang, Chuang Li, Liwei Song, Zhinan Zeng et al.
High-order harmonics were generated with neon gas by using 12-fs midinfrared laser pulses with stabilized carrier-envelope phase (CEP). At some specific CEP, a broad supercontinuum of the extreme ultraviolet spectrum can be obtained. Two distinct continuous spectral regimes are found by numerical si ... [Phys. Rev. A 85, 033410 ] published .

Alignment-dependent ionization of H: From multiphoton ionization to tunneling ionization

Bin Zhang, Jianmin Yuan, and Zengxiu Zhao
We investigate the strong-field ionization for the ground state of H by numerically solving the three-dimensional (3D) time-dependent Schrodinger equation (TDSE), and comparisons have been made among the TDSE, the different versions of molecular strong-field approximation (MO-SFA) and the molecular ... [Phys. Rev. A 85, 033421 ] published .

Metric for three-dimensional alignment of molecules

Varun Makhija, Xiaoming Ren, and Vinod Kumarappan
In an effort to clarify the three-dimensional alignment dynamics of polyatomic molecules, we propose a single measure for the degree of angular confinement of such molecules. The measure proposed for three-dimensional orientation is the angle of the single rotation that takes the molecule to the des ... [Phys. Rev. A 85, 033425 ] published .

Protonic structure of CHOH described by electroprotonic wave functions

Tsuyoshi Kato and Kaoru Yamanouchi
The electroprotonic ground-state wave function of CHOH is calculated beyond the Born-Oppenheimer (BO) approximation using multiconfiguration wave-function theory for a system composed of electrons and protons. A CHOH molecule is treated as a quasidiatomic molecule in which orbitals for both electron ... [Phys. Rev. A 85, 034504 ] published .

Explosions of Xenon Clusters in Ultraintense Femtosecond X-Ray Pulses from the LCLS Free Electron Laser

H. Thomas, A. Helal, K. Hoffmann, N. Kandadai, J. Keto et al.
Explosions of large Xe clusters (~11 000) irradiated by femtosecond pulses of 850 eV x-ray photons focused to an intensity of up to 10 W/cm from the Linac Coherent Light Source were investigated experimentally. Measurements of ion charge-state distributions and energy spectra exhibit strong evidenc ... [Phys. Rev. Lett. 108, 133401 ] published .

Communication: Quantum Zeno-based control mechanism for molecular fragmentation

C. Sanz-Sanz, A. S. Sanz, T. Gonzalez-Lezana, O. Roncero, and S. Miret-Artes
A quantum control mechanism is proposed for molecular fragmentation processes within a scenario grounded on the quantum Zeno effect. In particular, we focus on the van der Waals Ne-Br complex, which displays two competing dissociation channels via vibrational and electronic predissociation. Accordin ... [J. Chem. Phys. 136, 121101 (2012)] published Thu Mar 22, 2012.

Femtosecond pulses and dynamics of molecular photoexcitation: RbCs example

B. E. Londono, A. Derevianko, J. E. Mahecha, A. Crubellier, and E. Luc-Koenig
We investigate the dynamics of molecular photoexcitation by unchirped femtosecond laser pulses using RbCs as a model system. This study is motivated by a goal of optimizing a two-color scheme of transferring vibrationally excited ultracold molecules to their absolute ground state. In this scheme the ... [Phys. Rev. A 85, 033419 ] published .

Recollision Dynamics and Phase Diagram for Nonsequential Double Ionization with Circularly Polarized Laser Fields

L. B. Fu, G. G. Xin, D. F. Ye, and J. Liu
A semiclassical quasistatic model is used to investigate the recollision dynamics in circularly polarized laser fields. A velocity window for recollision to occur is found. Only when the return electron's orbits are irregular does significant double ionization take place. The model reproduces the ex ... [Phys. Rev. Lett. 108, 103601 ] published .

Ultrafast X-Ray Scattering of Xenon Nanoparticles: Imaging Transient States of Matter

C. Bostedt, E. Eremina, D. Rupp, M. Adolph, H. Thomas et al.
Femtosecond x-ray laser flashes with power densities of up to 10 W/cm at 13.7 nm wavelength were scattered by single xenon clusters in the gas phase. Similar to light scattering from atmospheric microparticles, the x-ray diffraction patterns carry information about the optical constants of the obje ... [Phys. Rev. Lett. 108, 093401 ] published .

Monotonically convergent optimization in quantum control using Krotov's method

Daniel M. Reich, Mamadou Ndong, and Christiane P. Koch
The non-linear optimization method developed by A. Konnov and V. Krotov [Autom. Remote Cont. (Engl. Transl.) 60, 1427 (1999)] has been used previously to extend the capabilities of optimal control theory from the linear to the non-linear Schrodinger equation [S. E. Sklarz and D. J. Tannor, Phys. Rev ... [J. Chem. Phys. 136, 104103 (2012)] published Fri Mar 9, 2012.

UV photodissociation dynamics of iodobenzene: Effects of fluorination

Daniel Murdock, Martin B. Crow, Grant A. D. Ritchie, and Michael N. R. Ashfold
The UV photochemistry of various fluorinated iodobenzenes (4-fluoro-, 2,4-difluoro-, 3,5-difluoro-, and perfluoro-iodobenzene) has been investigated at many wavelengths by velocity map imaging, time-resolved near infrared absorption spectroscopy and (spin-orbit resolved) ab initio calculations of th ... [J. Chem. Phys. 136, 124313 (2012)] published Thu Mar 29, 2012.

Two-photon excited fluorescence enhancement with broadband versus tunable femtosecond laser pulse excitation

Chao Wang and Alvin T. Yeh
The inverse relationship between two-photon excited fluorescence (TPEF) and laser pulse duration suggests that two-photon microscopy (TPM) performance may be improved by decreasing pulse duration. However, for ultrashort pulses of sub-10 femtosecond (fs) in duration, its spectrum contains the effect ... [J. Biomed. Opt. 17, 025003 (2012)] published Fri Mar 2, 2012.

Cofactor-specific photochemical function resolved by ultrafast spectroscopy in photosynthetic reaction center crystals

Libai Huang, Nina Ponomarenko, Gary P. Wiederrecht, and David M. Tiede
High-resolution mapping of cofactor-specific photochemistry in photosynthetic reaction centers (RCs) from Rhodobacter sphaeroides was achieved by polarization selective ultrafast spectroscopy in single crystals at cryogenic temperature. By exploiting the fixed orientation of cofactors within crysta ... [Proc. Natl. Acad. Sci. U.S.A. 109, 4851 (2012)] published Thu Mar 29, 2012.

Kinetic energy release in fragmentation processes following electron emission: A time-dependent approach

Ying-Chih Chiang, Frank Otto, Hans-Dieter Meyer, and Lorenz S. Cederbaum
A time-dependent approach for the kinetic energy release (KER) spectrum is developed for a fragmentation of a diatomic molecule after an electronic decay process, e.g., Auger process. It allows one to simulate the time-resolved spectra and provides more insight into the molecular dynamics than the t ... [J. Chem. Phys. 136, 114111 (2012)] published Mon Mar 19, 2012.

Ultrafast internal conversion in ethylene. II. Mechanisms and pathways for quenching and hydrogen elimination

T. K. Allison, H. Tao, W. J. Glover, T. W. Wright, A. M. Stooke et al.
Through a combined experimental and theoretical approach, we study the nonadiabatic dynamics of the prototypical ethylene (CH) molecule upon pi --> pi excitation with 161 nm light. Using a novel experimental apparatus, we combine femtosecond pulses of vacuum ultraviolet and extreme ultraviolet (XUV) ... [J. Chem. Phys. 136, 124317 (2012)] published Fri Mar 30, 2012.

Thermal effects on energetics and dynamics in water cluster anions (HO)

Ryan M. Young, Margaret A. Yandell, Sarah B. King, and Daniel M. Neumark
The electron binding energies and relaxation dynamics of water cluster anions (HO) (11 <= n <= 80) formed in co-expansions with neon were investigated using one-photon and time-resolved photoelectron imaging. Unlike previous experiments with argon, water cluster anions exhibit only one isomer class, ... [J. Chem. Phys. 136, 094304 (2012)] published Fri Mar 2, 2012.

Communication: Time-resolved fluorescence of highly single crystalline molecular wires of azobenzene

Ah-Young Jee, Yumin Lee, Minyung Lee, and Myung Hwa Kim
We report the enhanced fluorescence with the remarkably long lifetime (1.17 ns) in the first excited state (S) of highly crystalline molecular wires of azobenzene at the excitation wavelength of 467 nm for the first time. This observation suggests that trans-cis photoisomerization through the rotati ... [J. Chem. Phys. 136, 121104 (2012)] published Fri Mar 30, 2012.

Advances in ultrafast time resolved fluorescence physics for cancer detection in optical biopsy

R. R. Alfano
We discuss the use of time resolved fluorescence spectroscopy to extract fundamental kinetic information on molecular species in tissues. The temporal profiles reveal the lifetime and amplitudes associated with key active molecules distinguishing the local spectral environment of tissues. The femtos ... [AIP Advances 2, 011103 (2012)] published Wed Mar 21, 2012.

Influence of environment induced correlated fluctuations in electronic coupling on coherent excitation energy transfer dynamics in model photosynthetic systems

Pengfei Huo and David F. Coker
Two-dimensional photon-echo experiments indicate that excitation energy transfer between chromophores near the reaction center of the photosynthetic purple bacterium Rhodobacter sphaeroides occurs coherently with decoherence times of hundreds of femtoseconds, comparable to the energy transfer time s ... [J. Chem. Phys. 136, 115102 (2012)] published Thu Mar 15, 2012.

Biological effectiveness on live cells of laser driven protons at dose rates exceeding 10 Gy/s

D. Doria, K. F. Kakolee, S. Kar, S. K. Litt, F. Fiorini et al.
The ultrashort duration of laser-driven multi-MeV ion bursts offers the possibility of radiobiological studies at extremely high dose rates. Employing the TARANIS Terawatt laser at Queen's University, the effect of proton irradiation at MeV-range energies on live cells has been investigated at dose ... [AIP Advances 2, 011209 (2012)] published Thu Mar 22, 2012.

Injector for scattering measurements on fully solvated biospecies

U. Weierstall, J. C. H. Spence, and R. B. Doak
We describe a liquid jet injector system developed to deliver fully solvated microscopic target species into a probe beam under either vacuum or ambient conditions. The injector was designed specifically for x-ray scattering studies of biological nanospecies using x-ray free electron lasers and thir ... [Rev. Sci. Instrum. 83, 035108 (2012)] published Wed Mar 21, 2012.

Air-guided photonic-crystal-fiber pulse-compression delivery of multimegawatt femtosecond laser output for nonlinear-optical imaging and neurosurgery

Aleksandr A. Lanin, Il'ya V. Fedotov, Dmitrii A. Sidorov-Biryukov, Lyubov V. Doronina-Amitonova, Olga I. Ivashkina et al.
Large-core hollow photonic-crystal fibers (PCFs) are shown to enable a fiber-format air-guided delivery of ultrashort infrared laser pulses for neurosurgery and nonlinear-optical imaging. With an appropriate dispersion precompensation, an anomalously dispersive 15-[mu]m-core hollow PCF compresses 51 ... [Appl. Phys. Lett. 100, 101104 (2012)] published Tue Mar 6, 2012.

Signatures of correlated excitonic dynamics in two-dimensional spectroscopy of the Fenna-Matthew-Olson photosynthetic complex

Justin R. Caram, Nicholas H. C. Lewis, Andrew F. Fidler, and Gregory S. Engel
Long-lived excitonic coherence in photosynthetic proteins has become an exciting area of research because it may provide design principles for enhancing the efficiency of energy transfer in a broad range of materials. In this publication, we provide new evidence that long-lived excitonic coherence i ... [J. Chem. Phys. 136, 104505 (2012)] published Mon Mar 12, 2012.

Two-dimensional-Raman-terahertz spectroscopy of water: Theory

Peter Hamm and Janne Savolainen
We discuss the hybrid 2D-Raman-THz spectroscopy of liquid water. This two-dimensional spectroscopy is designed to directly work in the low-frequency range of the intermolecular degrees of freedom. The information content of 2D-Raman-THz spectroscopy is similar to 2D-Raman or 2D-THz spectroscopy, but ... [J. Chem. Phys. 136, 094516 (2012)] published Wed Mar 7, 2012.

Optimal control of open quantum systems: A combined surrogate Hamiltonian optimal control theory approach applied to photochemistry on surfaces

Erik Asplund and Thorsten Kluner
In this paper, control of open quantum systems with emphasis on the control of surface photochemical reactions is presented. A quantum system in a condensed phase undergoes strong dissipative processes. From a theoretical viewpoint, it is important to model such processes in a rigorous way. In this ... [J. Chem. Phys. 136, 124118 (2012)] published Fri Mar 30, 2012.

Exciton coherence lifetimes from electronic structure

John A. Parkhill, David G. Tempel, and Alan Aspuru-Guzik
We model the coherent energy transfer of an electronic excitation within covalently linked aromatic homodimers from first-principles. Our results shed light on whether commonly used models of the bath calculated via detailed electronic structure calculations can reproduce the key dynamics. For the s ... [J. Chem. Phys. 136, 104510 ] published .

Frontiers in passively mode-locked high-power thin disk laser oscillators

Cyrill R. E. Baer, Oliver H. Heckl, Clara J. Saraceno, Cinia Schriber, Christian Krankel et al.
Semiconductor saturable absorber mirror (SESAM) mode-locked thin disk lasers define the state-of-the-art performance for high average power and high pulse energy femtosecond laser oscillators. To date pulse energies above 30 [mu]J and average powers above 140 W have been demonstrated. In this paper ... [Opt. Express 20, 7054 (2012)] published Thu Mar 29, 2012.

Octave-spanning ultrafast OPO with 2.6-6.1[mu]m instantaneous bandwidth pumped by femtosecond Tm-fiber laser

Nick Leindecker, Alireza Marandi, Robert L. Byer, Konstantin L. Vodopyanov, Jie Jiang et al.
We report the extension of broadband degenerate OPO operation further into mid-infrared. A femtosecond thulium fiber laser with output centered at 2050 nm synchronously pumps a 500-[mu]m-long crystal of orientation patterned GaAs providing broadband gain centered at 4.1 [mu]m. We observe a pump thre ... [Opt. Express 20, 7046 (2012)] published Thu Mar 29, 2012.

Multi-microjoule, MHz repetition rate Ti:sapphire ultrafast regenerative amplifier system

Xiaoshi Zhang, Eric Schneider, Greg Taft, Henry Kaptyen, Margaret Murnane et al.
We demonstrate a cryogenically cooled Ti:sapphire ultrafast regenerative amplifier laser system producing >20 [mu]J energies at 50 kHz, >12 [mu]J at 200 kHz and >3.5 [mu]J at 1MHz with repetition rates continuously tunable from 50 kHz up to 1.7 MHz in a footprint of only 60x180 cm. This laser uses d ... [Opt. Express 20, 7015 (2012)] published Thu Mar 29, 2012.

High power laser pulses with voltage controlled durations of 400 1000 ps

F. Harth, T. Ulm, M. Luhrmann, R. Knappe, A. Klehr et al.
We report on the generation and amplification of pulses with pulse widths of 400 1000 ps at 1064 nm. For pulse generation an ultra-fast semiconductor modulator is used that modulates a cw-beam of a DFB diode laser. The pulse lengths could be adjusted by the use of a voltage control. The pulses were ... [Opt. Express 20, 7002 (2012)] published Thu Mar 29, 2012.

The development and application of femtosecond laser systems

W. Sibbett, A. A. Lagatsky, and C. T. A. Brown
Some background as well as recent progress in the development of femtosecond lasers are discussed together with a brief outline of a few representative emergent applications in biology and medicine that are underpinned by access to such sources. We also provide a short summary of other contributions ... [Opt. Express 20, 6989 (2012)] published Thu Mar 29, 2012.

A bright point source of ultrashort hard x-ray pulses using biological cells

M. Krishnamurthy, Sudipta Mondal, Amit D. Lad, Kartik Bane, Saima Ahmed et al.
We demonstrate that the interaction of intense femtosecond light on a plain solid substrate can be substantially altered by a few micron layer coating of bacterial cells, live or dead. Using E. Coli cells, we show that at an intensity of 10W cm, the bremsstraahlung hard x-ray emission (up to 300 keV ... [Opt. Express 20, 5754 (2012)] published Thu Mar 15, 2012.

2 [mu]m femtosecond fiber laser at low repetition rate and high pulse energy

Lih-Mei Yang, Peng Wan, Vladimir Protopopov, and Jian Liu
In the paper, a 2 [mu]m high energy fs fiber laser is presented based on Tm doped fiber at a low repetition rate. The seed laser was designed to generate pulse train at 2 [mu]m at a pulse repetition rate of 2.5 MHz. The low repetition rate seed oscillator eliminated extra devices such as AO pulse pi ... [Opt. Express 20, 5683 (2012)] published Thu Mar 15, 2012.

Active stabilization for optically synchronized optical parametric chirped pulse amplification

Alexander Schwarz, Moritz Ueffing, Yunpei Deng, Xun Gu, Hanieh Fattahi et al.
The development of new high power laser sources tends toward optical parametric chirped pulse amplification (OPCPA) in recent years. One of the difficulties in OPCPA is the the temporal overlap between pump and seed pulses. In this work we characterize our timing jitter on a single-shot basis using ... [Opt. Express 20, 5557 (2012)] published Thu Mar 15, 2012.

175 fs Tm:LuO laser at 2.07 [mu]m mode-locked using single-walled carbon nanotubes

Andreas Schmidt, Philipp Koopmann, Gunter Huber, Peter Fuhrberg, Sun Young Choi et al.
Singlewalled carbon nanotube saturable absorbers were designed and fabricated for passive mode-locking of bulk lasers operating in the 2 [mu]m spectral range. Mode-locked lasers based on Tm:LuO single crystals containing different Tm-doping concentrations were studied. Nearly transform-limited pulse ... [Opt. Express 20, 5313 (2012)] published Thu Mar 15, 2012.

Pulsed operation of a high average power Yb:YAG thin-disk multipass amplifier

M. Schulz, R. Riedel, A. Willner, S. Dusterer, M. J. Prandolini et al.
An Yb:YAG thin-disk multipass laser amplifier system was developed operating in a 10 Hz burst operation mode with 800 [mu]s burst duration and 100 kHz intra-burst repetition rate. Methods for the suppression of parasitic amplified spontaneous emission are presented. The average output pulse energy i ... [Opt. Express 20, 5038 (2012)] published Thu Mar 15, 2012.

Efficient Mode-Locking of Sub-70-fs Ti:Sapphire Laser by Graphene Saturable Absorber

In Hyung Baek, Hwang Woon Lee, Sukang Bae, Byung Hee Hong, Yeong Hwan Ahn et al.
The efficient passive mode-locking of a Ti:sapphire laser with a monolayer graphene saturable absorber is demonstrated for the first time. High-quality and large-area (1 in.) monolayer graphene, synthesized by chemical vapor deposition, exhibits ultrafast recovery times and excellent nonlinear absor ... [Appl. Phys. Express 5, 032701 (2012)] published Thu Mar 15, 2012.

All-fiber broadband supercontinuum source with high efficiency in a step-index high nonlinear silica fiber

Weiqing Gao, Meisong Liao, Lingzhen Yang, Xin Yan, Takenobu Suzuki et al.
We demonstrate an all-fiber broadband supercontinuum (SC) source with high efficiency in a step-index high nonlinear silica fiber, which was pumped by a 1557 nm subpicosecond-pulse laser in the normal dispersion region. The broad SC spectrum covers the spectral range from 840 to 2390 nm, and the 10 ... [Appl. Opt. 51, 1071 (2012)] published Tue Mar 13, 2012.

High-fidelity, 160 fs, 5 [mu]J pulses from an integrated Yb-fiber laser system with a fiber stretcher matching a simple grating compressor

A. Fernandez, K. Jespersen, L. Zhu, L. Gruner-Nielsen, A. Baltuska et al.
Although femtosecond microjoule Yb-fiber systems are attractive because of a straightforward power scalability, they inherently suffer from a lowered pulse fidelity as a result of complex dispersion and nonlinearity management. Here, we present an integrated Yb-fiber system delivering high-fidelity ... [Opt. Lett. 37, 927 (2012)] published Thu Mar 1, 2012.

175 GHz, 400-fs-pulse harmonically mode-locked surface emitting semiconductor laser.

Keith G. Wilcox, Adrian H. Quarterman, Vasilis Apostolopoulos, Harvey E. Beere, Ian Farrer et al.
We report a harmonically mode-locked vertical external cavity surface emitting laser (VECSEL) producing 400 fs pulses at a repetition frequency of 175 GHz with an average output power of 300 mW. Harmonic mode-locking was established using a 300 [mu]m thick intracavity single crystal diamond heat spr ... [Opt. Express 20, 7040 (2012)] published Thu Mar 29, 2012.

Free electron laser oscillators with tapered undulators: Inclusion of harmonic generation and pulse propagation

G. Dattoli, S. Pagnutti, P. L. Ottaviani, and V. Asgekar
We review the theory of free-electron laser (FEL) oscillators operating with tapered undulators. We have considered the case of a uniform tapering and introduced a parameter which characterizes the effect of the tapering on the gain and the saturation intensity. We have analyzed the effect of the ta ... [Phys. Rev. ST Accel. Beams 15, 030708 ] published .

Low-charge, hard x-ray free electron laser driven with an X-band injector and accelerator

Yipeng Sun (孙一鹏), Chris Adolphsen, Cecile Limborg-Deprey, Tor Raubenheimer, and Juhao Wu
After the successful operation of the Free Electron Laser in Hamburg (FLASH) and the Linac Coherent Light Source (LCLS), soft and hard x-ray free electron lasers (FELs) are being built, designed, or proposed at many accelerator laboratories. Acceleration employing lower frequency rf cavities, rangin ... [Phys. Rev. ST Accel. Beams 15, 030703 ] published .

2.1 [mu]m waveguide laser fabricated by femtosecond laser direct-writing in Ho, Tm:ZBLAN glass

D. G. Lancaster, S. Gross, H. Ebendorff-Heidepriem, A. Fuerbach, M. J. Withford et al.
We report the first Ho doped waveguide laser, which was realized by femtosecond direct-writing of a depressed cladding structure into ZBLAN glass. Tm sensitizing allows the 9 mm long Ho gain medium to be conveniently pumped at 790 nm, achieving an optical-to-optical slope efficiency of 20% and a thr ... [Opt. Lett. 37, 996 (2012)] published Thu Mar 29, 2012.

Ultrafast laser-written dual-wavelength waveguide laser

Martin Ams, Peter Dekker, Graham D. Marshall, and Michael J. Withford
We report the performance of a dual-wavelength waveguide laser based on a phase-modulated sampled-grating architecture fabricated using the femtosecond laser direct-write technique. The waveguide laser was written in Yb-doped phosphate glass and had a narrow linewidth (<10 pm), high signal-to-noise ... [Opt. Lett. 37, 993 (2012)] published Thu Mar 29, 2012.

Highly efficient 1 GHz repetition-frequency femtosecond Yb:KY(WO) laser

Thomas C. Schratwieser, Christopher G. Leburn, and Derryck T. Reid
We present a highly efficient, diode-pumped, femtosecond Yb:KY(WO) (Yb:KYW) laser operating at a 1.024 GHz repetition rate. The output was centered at a wavelength of 1042 nm and had a bandwidth of 3.8 nm, leading to transform-limited pulses with durations of 278 fs determined by fringe-resolved aut ... [Opt. Lett. 37, 1133 (2012)] published Thu Mar 29, 2012.

Synchronized retroreflection-pumped femtosecond optical parametric oscillator

A. Esteban-Martin, V. Ramaiah-Badarla, and M. Ebrahim-Zadeh
We report a flexible technique for threshold reduction and output power enhancement in synchronously pumped optical parametric oscillators (SPOPOs) based on synchronized retroreflection of the undepleted pump using a collimating system and a delay line, which allows easy and independent adjustment o ... [Opt. Lett. 37, 1091 (2012)] published Thu Mar 29, 2012.

Monotonically chirped pulse evolution in an ultrashort pulse thulium-doped fiber laser

Frithjof Haxsen, Dieter Wandt, Uwe Morgner, Jorg Neumann, and Dietmar Kracht
We report on monotonically positively chirped pulse operation of a hybridly mode-locked thulium fiber laser. Dispersion management was realized with a small-core, high-NA fiber providing normal dispersion in the 2 [mu]m wavelength region. The laser delivered pulses with 0.7 nJ energy at the 1927 nm ... [Opt. Lett. 37, 1014 (2012)] published Thu Mar 29, 2012.

Efficient femtosecond pulse generation in an all-normal-dispersion Yb:fiber ring laser at 605 MHz repetition rate

Hongyu Yang, Aimin Wang, and Zhigang Zhang
We report a 1030 nm-wavelength Yb:fiber laser that produces the shortest/direct output pulse duration (502 fs) among all-normal-dispersion fiber lasers at the highest repetition rate (605 MHz) among the passively fundamentally mode-locked fiber lasers. The laser also exhibits an optical efficiency o ... [Opt. Lett. 37, 954 (2012)] published Thu Mar 1, 2012.

Widely linear and non-phase-matched optical-to-terahertz conversion on GaSe:Te crystals

Wei-Chen Chu, Shin An Ku, Harn Jiunn Wang, Chih Wei Luo, Yu. M. Andreev et al.
We demonstrate the widely linear and broadband terahertz (THz) generation on GaSe:Te crystals by femtosecond laser pulses. It was found that the dopant, Te atoms, in GaSe crystals significantly enhances the efficiency of THz generation, and its central fr ... [Opt. Lett. 37, 945 (2012)] published Thu Mar 1, 2012.

High-average-power, carrier-envelope phase-stable, few-cycle pulses at 2.1 [mu]m from a collinear BiBO optical parametric amplifier

F. Silva, P. K. Bates, A. Esteban-Martin, M. Ebrahim-Zadeh, and J. Biegert
We generate self-carrier-to-envelope phase-stable, 630 [mu]J pulses, centered at 2.1 [mu]m, with 42 fs (6 cycle) duration based on collinear optical parametric amplification in BiBO at 3 kHz. These pulses are generated through a traveling wave amplifier scheme, and the bandwidth supports 28 fs (4 cy ... [Opt. Lett. 37, 933 (2012)] published Thu Mar 1, 2012.

Generation of hard x rays by femtosecond laser pulse interaction with solid targets in atmosphere

Alexey G. Zhidkov, Sergey A. Pikuz, Anatoly Ya. Faenov, Oleg V. Chefonov, Andrey V. Ovchinnikov et al.
X ray radiation as high as 50 keV, including K of Ba and Mo, have been observed from a solid target during the interaction of low energy ?0.65 mJ, 1 kHz 40 femtosecond laser pulses focused in air at atmospheric pressure. Energetic electrons generating such x rays are possibly produced when the fiel ... [Opt. Lett. 37, 884 (2012)] published Thu Mar 1, 2012.

490 fs pulse generation from a passive C-band AlGaInAs/InP quantum well mode-locked laser

Lianping Hou, Mohsin Haji, John H. Marsh, and A. Catrina Bryce
We report femtosecond pulses from a passive C-band two-section AlGaInAs/InP mode-locked laser with a monolithically integrated passive waveguide made by quantum well intermixing. Without any external pulse compression, Lorentzian pulses are generated at a repetition frequency of ?38 GHz with 490 fs ... [Opt. Lett. 37, 773 (2012)] published Thu Mar 1, 2012.

Direct generation of intense extreme-ultraviolet supercontinuum with 35-fs, 11-mJ pulses from a femtosecond laser amplifier

Bin Zeng, Wei Chu, Guihua Li, Jinping Yao, Jielei Ni et al.
We report on the generation of an intense extreme-ultraviolet (EUV) supercontinuum with photon energies spanning from 35 to 50 eV (i.e., supporting an isolated attosecond pulse with a duration of ~271 as) by loosely focusing 35 fs, 11 mJ pulses from a femtosecond laser amplifier into a 10-mm-long ga ... [Phys. Rev. A 85, 033839 ] published .

Extreme ultraviolet light source based on intracavity high harmonic generation in a mode locked Ti:sapphire oscillator with 9.4 MHz repetition rate

Enikoe Seres, Jozsef Seres, and Christian Spielmann
We report on the realization of an intracavity high harmonic source with a cutoff above 30 eV. The EUV source is based on a high power, hard-aperture, Kerr-lens mode-locked Ti:sapphire oscillator with a repetition rate of 9.4 MHz. The laser is operated in the net negative dispersion regime resulting ... [Opt. Express 20, 6185 (2012)] published Thu Mar 15, 2012.

Free electron terahertz wave radiation source with two-section periodical waveguide structures

Weihao Liu, Sen Gong, Yaxin Zhang, Jun Zhou, Ping Zhang et al.
We analyze a free electron terahertz wave radiation source with two-section periodical waveguide structure (PWS), where the first section (section-I) is used to pre-modulate the electron beam and the second section (section-II) is for terahertz wave generation. By means of theoretical analysis and n ... [J. Appl. Phys. 111, 063107 (2012)] published Mon Mar 26, 2012.

Generation of High-Energy Few-Cycle Laser Pulses by Using the Ionization-Induced Self-Compression Effect

S. A. Skobelev, A. V. Kim, and O. Willi
A mechanism behind the ionization-induced self-compression effect for ultrashort laser pulses propagating in gas-filled capillaries is proposed. It is shown that as a result of excitation of the nonlinear-plasma waveguide laser pulses producing gas ionization can be self-compressed to few-cycle dura ... [Phys. Rev. Lett. 108, 123904 ] published .

A tuneable ultra-compact high-power, ultra-short pulsed, bright gamma-ray source based on bremsstrahlung radiation from laser-plasma accelerated electrons

S. Cipiccia, S. M. Wiggins, R. P. Shanks, M. R. Islam, G. Vieux et al.
The laser driven plasma wakefield accelerator is a very compact source of high energy electrons. When the quasi-monoenergetic beam from these accelerators passes through dense material, high energy bremsstrahlung photons are emitted in a collimated beam with high flux. We show how a source based on ... [J. Appl. Phys. 111, 063302 (2012)] published Tue Mar 27, 2012.

Laser phase errors in seeded free electron lasers

D. Ratner, A. Fry, G. Stupakov, and W. White
Harmonic seeding of free electron lasers has attracted significant attention as a method for producing transform-limited pulses in the soft x-ray region. Harmonic multiplication schemes extend seeding to shorter wavelengths, but also amplify the spectral phase errors of the initial seed laser, and m ... [Phys. Rev. ST Accel. Beams 15, 030702 ] published .

Tailoring chirp in spin-lasers

Guilhem Boeris, Jeongsu Lee, Karel Vyborny, and Igor Zutic
The usefulness of semiconductor lasers is often limited by the undesired frequency modulation, or chirp, a direct consequence of the intensity modulation, and carrier dependence of the refractive index in the gain medium. In spin-lasers, realized by injecting, optically or electrically, spin-polariz ... [Appl. Phys. Lett. 100, 121111 (2012)] published Wed Mar 21, 2012.

Polarization insensitive in-fiber mode-locker based on carbon nanotube with N-methyl-2-pryrrolidone solvent filled fiber microchamber

Chengbo Mou, Aleksey G. Rozhin, Raz Arif, Kaiming Zhou, and Sergei Turitsyn
We report an in-fiber laser mode locker based on carbon nanotube with n-methyl-2-pryrrolidone solvent filled in-fiber microchamber. Symmetrically femtosecond laser fabricated in-fiber microchamber with randomly oriented nanotubes assures polarization insensitive oscillation of laser mode locking. Th ... [Appl. Phys. Lett. 100, 101110 (2012)] published Thu Mar 8, 2012.

High numerical aperture hybrid optics for two-photon polymerization

Frank Burmeister, Uwe D. Zeitner, Stefan Nolte, and Andreas Tunnermann
We report on an immersion hybrid optics specially designed for focusing ultrashort laser pulses into a polymer for direct laser writing via two-photon polymerization. The hybrid optics allows for well-corrected focusing over a large working distance range of 577 [mu]m with a numerical aperture (NA) ... [Opt. Express 20, 7994 (2012)] published Thu Mar 29, 2012.

Coherence properties of a broadband femtosecond mid-IR optical parametric oscillator operating at degeneracy

Alireza Marandi, Nick C. Leindecker, Vladimir Pervak, Robert L. Byer, and Konstantin L. Vodopyanov
We study coherence properties of a chi optical parametric oscillator (OPO), which produces 2/3-octave-wide spectrum centered at the subharmonic (3120 nm) of the femtosecond pump laser. Our method consists of interfering the outputs of two identical, but independent OPOs pumped by the same laser. We ... [Opt. Express 20, 7255 (2012)] published Thu Mar 29, 2012.