Laser diode modulation of 10.6 mu m radiation in GaAs/AlGaAs quantum wells

摘要

The first demonstration of all-optical modulation of mid-infrared radiation based on intersubband absorption under optical pumping by a modulated laser diode in undoped GaAs/AlGaAs quantum wells is presented. The mid-infrared modulation depth and the frequency bandwidth of the modulator are analysed as a function of the laser diode pump power. Both parameters exhibit a square root dependence with large pump intensity. This novel modulation technique can be used to evaluate the relaxation rates of the carriers within the conduction band. Excellent agreement is obtained with the results of a simple model based on the carrier rate equation.