Dispersion, Threshold and Gain Characteristics of Brillouin Scattered Stokes Mode in Ion-Implanted Semiconductor Quantum Plasmas

Abstract

The dispersion, threshold, and gain characteristics of the Brillouin scattered Stokes mode (BSSM) in ion-implanted semiconductor quantum plasmas are analytically investigated using coupled mode theory. Taking into account that the origin of stimulated Brillouin scattering lies in nonlinear induced polarisation of the medium, expressions are derived for complex effective Brillouin susceptibility (due to electrons and implanted colloids) and consequently the threshold pump amplitude and the gain constant of BSSM. Inclusion of quantum effects (QEs) is done via quantum correction term in the hydrodynamic model of semiconductor plasmas. QEs modify the dispersion, threshold and gain characteristics of BSSM in ion-implanted semiconductor plasmas. In contrast to the threshold and gain characteristics of BSSM, which are impacted only by electrons and are unaffected by implanted charged colloids, the Brillouin susceptibility caused by implanted colloids has a significant impact on the dispersion characteristics of BSSM. Finally, an extensive numerical study of the n-InSb/CO₂ laser system is performed for two different cases: (i) without QEs and (ii) with QEs. In both cases, the analysis offers two achievable resonances, at which the changes of sign as well as an enhancement of real part of effective Brillouin susceptibility and an enhancement of effective Brillouin gain constant are obtained. When QEs are included in the analysis, the entire spectrum shifts towards decreased levels of electron and colloidal carrier concentration.