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

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 (Γ_a) over a wide range of externally applied magnetic field (incorporated in terms of cyclotron frequency ω_c). The results indicate that in absence of damping parameter, the absorption of coherent electromagnetic radiation takes place completely in all possible wavelength regimes when ω_c~ (v² + ω₀²)^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. (author)