Piezoelectric Contributions to Parametric Amplification of Acoustical Phonons in Magnetized n-InSb Crystal

Abstract: Using the hydrodynamic model of semiconductor-plasmas and following the coupled-mode approach, we develop a theoretical formulation to study piezoelectric contributions to parametric amplification of acoustical phonons in magnetized n-InSb crystal. The origin of nonlinear interaction is assumed to lie in effective second-order optical susceptibility arising due to nonlinear induced current density and electrostrictive polarization of the medium. Expressions are obtained for threshold pump amplitude for the onset of parametric process and parametric gain coefficient (well above the threshold pump field) in the presence and absence of piezoelectricity and/or externally applied magnetostatic field. Numerical analysis is made for n-InSb crystal irradiated by 10.6 m pulsed CO2 laser. The piezoelectric contributions to three-wave parametric amplification process are only in the presence of magnetostatic field. The parametric gain coefficient is independent of doping concentration for the cases when either/both piezoelectricity and magnetostatic field are absent. Around resonance (electron-cyclotron frequency ~ pump frequency), the parametric gain coefficient in the presence of piezoelectricity is 102 times higher than that in the absence of piezoelectricity. The analysis establishes the technological potentiality of transversely magnetized n-InSb as the host for parametric devices, like parametric amplifiers and oscillators. Keywords: Parametric amplification, Acoustical phonons, Piezoelectricity, Electrostriction, n-InSb crystal. PACS numbers: 42.65.-k, 78.55.Cr, 71.38.-k, 52.35.Mw.