Numerical analysis of laser diode longitudinally pumped solid‐state laser generation dynamics using traveling wave model

A detailed theoretical model for the description of generation dynamics of diode laser longitudinally pumped solid‐state lasers with active and/or passive Q‐switching using traveling wave approach is presented. The results of numerical simulations and analysis show that the distribution of generated laser pulse intensity and the other laser parameters along the resonator is very inhomogeneous. Therefore, the widely used point laser model cannot give accurate results when inside the resonator there are active or passive elements which lead to the strong modulation of the generated pulse intensities. First published online: 09 Jun 201

Research of the Dynamics of the Impulse Generation in solid-state Lasers

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A tool for modeling ptical beam propagation

A tool for modeling the propagation of optical beams is proposed and investigated. Truncated Laguerre-Gauss polynomial series are used for approximation of the field at any point in free space. Aposteriori error estimates in various norms are calculated using errors for input functions. The accumulation of truncation errors during space transition is investigated theoretically. The convergence rate of truncated LG series is obtained numerically for super-Gaussian beams. An optimization of algorithm realization costs is done by choosing parameters in such a way that the error reaches minimum value. Results of numerical experiments are presented

Sequential compression of the first and second Stokes pulses in a SRS amplifier pumped by picosecond pulses

In this work, compression of the first and the second Stokes pulses in a KGd(WO4)2 crystal in the accompanying SRS amplification regime was researched. It was analyzed how the minimum duration of the second Stokes pulse depends on the amplitude, duration and delay of the first Stokes pulse and what is the influence of a significant Kerr nonlinearity of the SRS medium. It was determined that the minimum duration of the compressed second Stokes pulse amounts to approximately 300 fs, and the duration at the beam axis - to only 70 fs. It was found that the complex spatio-temporal dynamics of the compression process and the Kerr nonlinearity of the medium increases significantly the pulse propagation factor M2Fizikos institutasVytauto Didžiojo universiteta

Aukšto efektyvumo Stokes'o impulsų Raman'o stiprinimas vandenilio linijos Dicke susiaurėjimo srityje

Fizikos institutasFizikos katedraVytauto Didžiojo universiteta

Trumpų lazerio impulsų spūdos nestacionarios priverstinės Brijueno sklaidos kompresoriuje skaitinis tyrimas

Trumpų lazerio impulsų spūdos dinamikai aprašyti naudotas stipriai nestacionarios priverstinės Brijueno sklaidos 3D modelis, kuriame atsižvelgiama į pluoštų fokusavimą, difrakciją, lūžio rodiklio Kero netiesiškumą ir garso bangos periodo bei relaksacijos trukmės įtaką. Skaitiniame algoritme pluoštų fokusavimo uždaviniui pritaikytas naujas adaptyvios radialinės koordinatės transformacijos ir aproksimacijos baigtiniais skirtumais metodas. Gauti rezultatai rodo, kad centrinės arti ašies esančios Stokso impulso dalies išskyrimas leidžia pasiekti praktiškai piosekundžių diapazono Stokso impulsų trukmę ir spūdos santykį, viršijantį 30 kartųResults of numerical investigation of the compression process of short pulses during essentially nonstationary SBS are presented, taking into account the diffraction and focusing of the interacting light beams and the finite oscillation period and lifetime of hypersound waves in nonlinear mediaFizikos institutasFizikos katedraGamtos mokslų fakultetasVytauto Didžiojo universiteta

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Fizikos institutasFizikos katedraGamtos mokslų fakultetasVytauto Didžiojo universiteta

Numerical modelling of compression of femtosecond first harmonics pulses at the conditions remote from the phase matching

This work presents the numerical analysis of the influence of the Kerr nonlinearity of the quadratically-nonlinear medium and the degree of the super-Gaussian distribution of the FF pulses to the duration, shape and the propagation factor of the FF pulses compressed to the maximum due to the cascaded nonlinearity and the group velocity dispersion. It was determined that a pulse with the initial duration of 120 fs and the initial Gaussian radial distribution is compressed almost twice, and it shortens at the beam center to almost 20 fs, and its propagation factor increases to 1.7-1.8Fizikos institutasVytauto Didžiojo universiteta

Cascaded pulse compression during transient stimulated Brillouin and Raman scattering

Fizikos institutasVytauto Didžiojo universiteta

Cascaded compression of the first and second Stokes pulses during forward transient stimulated Raman amplification

The results of numerical modelling of cascaded compression of the first and second Stokes pulses during regenerative regime of the forward transient stimulated Raman amplification are presented for the case when the walk-off length of the first Stokes pulse due to group velocity mismatch is shorter than the length of the nonlinear medium. The influence of the initial amplitudes of the seed first Stokes pulses, its durations and its time delay with respect to the pump pulse, the Kerr nonlinearity of the medium on the conversion efficiency, duration and propagation factor M-2 of the first and second Stokes pulse are studied. It is demonstrated that for the pump pulse duration of 1 ps the duration of the compressed second Stokes pulses in a KGW crystal near the beam axis may be approximately 14 times shorter than the pump pulse duration. It is shown that the propagation factor of the compressed pulses increases significantly because of complex spatial-temporal dynamics of compression and the influence of Kerr nonlinearity of Raman mediumFizikos institutasLietuvos energetikos institutasVytauto Didžiojo universiteta