Field Of Few-cycle Laser Pulse Research Articles

Theoretical study and 2D computational modeling of middle-infrared radiation generation in the field of few-cycle laser pulse propagating in GaSe slab waveguide

We have performed the theoretical study and 2D finite-difference time-domain-based computational modeling of middle-infrared radiation generation in the field of few-cycle laser pulse propagating in GaSe slab waveguide. The interaction of linearly polarized pulse with 1.98 um central wavelength, 22.44 fs duration, and electric field amplitudes 100 MV/m, propagated along the [010] crystalline direction of GaSe crystal with polarization aligned along [100] is considered. The crystal length chosen is equal to 21.78 um. Symmetric GaSe slab waveguides with 6.336 um, 7.92 um, 11.88 um, and 15.84 um thicknesses excited by the Gaussian pump beams with 3.96 um, 5.94 um, 8.91 um, and 11.88 um diameters, respectively, are considered. The 2D distributions of the electric fields are obtained by numerical integration of Maxwell’s equations’ systems. The spatially spectral normalized distributions of the electric fields are obtained. The efficiency of generated infrared (IR) radiation vs. spatial transverse coordinate is obtained.

Dynamics of difference frequency radiation generation in the field of few-cycle laser pulse propagating in GaAs crystal with domain structure

We consider the process of generation of difference frequency in a GaAs crystal with periodic domain structure during propagation of a few-cycle laser pulse in the crystal in the regime of weakly expressed chromatic dispersion. Method of lines is used to obtain numerical solution to the system of coupled nonlinear differential equations in partial derivatives describing the evolution of the electric field of a few-cycle laser pulse in GaAs crystal both with periodic and aperiodic domain structure. It is shown that employing GaAs crystal with domain structure allows controlling the instantaneous frequency of broadband pulse radiation at difference frequency.

Summary and difference frequency radiation generation in the field of few-cycle laser pulse propagating in GaSe

The results of numerical study of the generation process of summary and difference frequency radiations (SFR and DFR) arising via interaction of linearly polarized a few cycle laser pulses propagating in a GaSe crystal is present. The interaction of pulse having the central wavelengths of 1.98 μm, duration of 30 fs with the electric field amplitude 100 MV/m, propagating along the optical axis is considered. The thickness of GaSe crystal in numerical simulations is 198 μm. For study the pulse dynamic spectrum evolution the smoothed pseudo Wigner distribution (SPWVD) transformation was applied. In order to increase the time and frequency resolution of the pulse dynamic spectrum the Mexican-hat wavelet based continuous wavelet transform (CWT) was applied. The dependences of SFR and DFR generation efficiency versus propagation distance inside of crystal at fixed values of initial pump pulse amplitude 10, 50 and 100 MV/m are obtained. The SFR and DFR generation efficiency dependences versus initial pump pulse amplitude are obtained. It's shown that the maximum values of SFR and DFR generation efficiencies at initial pump pulse amplitude 100 MV/m are 4.8 × 10?3% and 2.7 × 10?3% respectively.

Generation of summary and difference frequency radiation in the field of few-cycle laser pulse propagating in periodically-poled lithium niobate

The results of numerical study of the generation process of summary and difference frequency radiations (SFR and DFR) arising via interaction of linearly polarized a few-cycle laser pulses propagating in a quasi-phase-matching (QPM) LiNbO3 crystal is present. Considered the interaction of pulses having the central wavelengths of 0.81 μm, duration of 10 fs with the electric field amplitude 600 MV/m, propagating along the normal to the optical axis. The period of QPM LiNbO3 crystal in numerical simulations is 12.6 μm and chosen such that QPM generation of DFR takes place at 3 μm. It is shown that at this period take place the simultaneous QPM for SFR at 0.41 μm, 0.36 μm, 0.33 μm, and 0.31 μm and for DFR at 3 μm wavelengths respectively.

Measuring the electric field of few-cycle laser pulses by attosecond cross correlation.

A new technique for directly measuring the electric field of linearly polarized few-cycle laser pulses is proposed. Based on the solution of the time-dependent Schrödinger equation (TDSE) for an H atom in the combined field of infrared (IR) femtosecond (fs) and ultraviolet (UV) attosecond (as) laser pulses we show that, as a function of the time delay between two pulses, the difference (or equivalently, asymmetry) of photoelectron signals in opposite directions (along the polarization vector of laser pulses) reproduces very well the profile of the electric field (or vector potential) in the IR pulse. Such ionization asymmetry can be used for directly measuring the carrier-envelope phase difference (i.e., the relative phase of the carrier frequency with respect to the pulse envelope) of the IR fs laser pulse.

Self-phase-matched high harmonic generation

Our theoretical analysis reveals that tunnel ionization significantly modifies the electric field of few-cycle laser pulses within a single oscillation period. This subcycle self-modulation is predicted to result in phase matching, making high harmonic generation in the x-ray regime possible for the first time. Such a radiation source opens novel possibilities in the investigation of matter with x-ray techniques, such as time resolved x-ray diffraction and absorption.