Soliton generation in stimulated Raman scattering and excitation of polar optical phonons

2015

AJCM

The system of nonlinear equations modeling the process of nonstationary stimulated Raman scattering (SRS) in noncentrosymmetric crystals for the waves on laser, Stokes, polariton, and phonon frequencies is investigated by using the numerical methods. The general case for amplitudes of waves that resulted in doubling of the number of equations is considered. It is shown that the application of the methods of finite differences to the computer simulation of transition regimes is completely consistent with the analytical results found for the asymptotical solutions in form of solitons. The obtained results also indicate that the laser pulses of Gaussian shape appearing at the boundary of nonlinear medium tend to become solitons of Lorentzian shape. It was also found that the formation of solitons occurs when the vibrations of optical phonons and that of electromagnetic wave were either in or out of phase. It is shown that all electromagnetic waves entering the medium with different speeds become solitons having the same speed. In the second part of the paper we considered the computer simulation of soliton stability with respect to small (weak) perturbations of all interacting waves. In the present paper we considered the case of evolution of those disturbances in the vicinity of peaks of solitons. The numerical analysis showed that in wide range of parameters the solitons were stable.

Section: Introductionsupporting

confidence: 65%

Section: Introductionsupporting

confidence: 65%

mentioning

confidence: 99%

See 1 more Smart Citation

Computer Simulation of Transition Regimes of Solitons in Stimulated Raman Scattering with Excitation of Polar Optical Phonons

2015

AJCM

“…The generation of three-wave solitons in the resonant LO-phonon-mediated interaction of two intense coherent polaritons is proposed in [47]. We considered the theory and computer simulation of simultons formation in stimulated Roman scattering by polaritons in dipole-active crystals [48] [49]. In past years progress was also achieved in the process of the realization of solitons at different frequencies [50] [51] [52].…”

Section: Introductionmentioning

confidence: 99%

Polarization Simultons in CARS by Polaritons

2023

JAMP

The system of shortened Maxwell's equations simulating the processes of evolution of the stimulated Raman scattering (SRS) by polaritons in anisotropic dipole-active crystals is obtained. The theory was developed for the case of cubic crystals which become anisotropic due to the deformation of the dielectric constant by the linearly polarized pump wave. The pump field is a linearly polarized plane electromagnetic wave. We report the results of the theoretical investigation of the possibility of the existence of a regime of pulse propagation as simultaneous travel of solitary waves in coherent anti-Stokes stimulated Raman scattering by polaritons in anisotropic crystals. The emphasis was made on the existence of both Stokes and anti-Stokes pulses propagating with two stable and perpendicular to the direction of travel polarizations. We showed the theoretical possibility of simultaneous propagation of pulses not only at frequencies of Stokes and anti-Stokes waves but the pump frequency as well. We obtained the expression for the gain factor g. It is also shown that the expression for g is consistent with the experimental results for the spectra of ZnS.

“…In quasi-stationary case, in absence of phase modulation of any kind, and given pump field, the system of equations for the 2 ε (Stokes) and 3 ε (polariton) can be reduced to the following (see (11) and (13) coefficients. This system is the part of more complex system considered in [21].…”

mentioning

confidence: 99%

Nonstationary Stimulated Raman Scattering by Polaritons in Continuum of Dipole-Active Phonons

2018

JAMP

The system of equations simulating the processes of nonstationary stimulated Raman scattering (SRS) with the excitation of polar optical phonons is obtained. This system is found by applying such standard methods as the nonstationary theory of perturbations, which resulted in the equations for the amplitudes of probabilities to find the discrete system in certain state, and slowly-varying amplitudes for the electromagnetic waves. It has been shown that the obtained system includes, as extremes, the case of classical interaction between electromagnetic field and resonant medium (including the "area theorem"), and the one related with SRS on optical phonons. We have conducted both theoretical and numerical investigation of simplified system assuming that the amplitudes of all electromagnetic waves (laser, Stokes, and polariton) were real (there was no destructive spatial-temporal phase modulation). Only low-order nonlinear processes are considered. It is shown that this system can be reduced to Sine-Gordon equation. This system can also be simplified to the equation that simulates the motion of physical pendulum from upper equilibrium position. The numerical study of nonstationary SRS when the electromagnetic field of laser radiation and Stokes excite both polariton emission and the continuum of dipole-active phonons has been carried out. The evolution of the intensity of the polariton wave as function of the length of nonlinear medium has been numerically analyzed.