Amplitude modulation and demodulation of a coherent electromagnetic wave in magnetized doped III-V semiconductors

Abstract

This present paper is concerned with the analytical study of the amplitude modulation and demodulation of a coherent electromagnetic wave in magnetized doped III-V semiconductors. Utilizing the hydrodynamic model of a semiconductor plasma, the modulation indices for upper (+) and lower (–) side bands have been obtained. The incorporation of carrier diffusion in the nonlinear laser-semiconductor interaction adds new dimension to the analysis. The numerical estimations have been made for n-InSb crystal at liquid nitrogen temperature illuminated by frequency doubled pulsed 10.6 µm CO2 laser. The problem has been analyzed in two different wave regimes (in the presence as well as absence of phenomenological acoustic damping parameter (Γa) over a wide range of externally applied magnetic field (incorporated in terms of cyclotron frequency ωc). The results indicate that in absence of damping parameter, the absorption of coherent electromagnetic radiation takes place completely in all possible wavelength regimes when ωc~ (v2 + ω)1/2; v and ω0 being the electron collision frequency and pump frequency, respectively. Moreover, the carrier diffusion modifies amplitude modulation and demodulation processes significantly. The damping parameter additionally assumes a significant role in choosing the range of parameters and selecting the modulated side band mode.