The Nonlinear Absorption Coefficient of Strong Electromagnetic WavesCaused by Electrons Confined in Quantum Wires

摘要

Analytic expressions for the nonlinear absorption coefficient of a strong electromagnetic wavecaused by electrons confined in cylindrical quantum wires are calculated by using the quantum ki-netic equation for electrons. The problem is considered for electron-phonon scattering mechanisms(electron-optical phonon scattering and electron-acoustic phonon scattering) in the absence of anexternal magnetic field and for electron-optical phonon scattering in the presence of an externalmagnetic field. The dependence of the nonlinear absorption coefficient on the intensity E0 and thefrequency Ω of the external strong electromagnetic wave, the temperature T of the system, theradius of the wires R, and the cyclotron frequency w_c(for the case of presence an externalmagnetic field) is obtained. The analytic expressions are numerically calculated and discussed forGaA_s/GaA_sAlquantum wires. The results are compared with those for normal bulk semiconduc-tors and quantum wells to show the differences.