ABSORPTION SATURATION OF INTERSUBBAND OPTICAL-TRANSITIONS IN GAAS/ALXGA1-XAS MULTIPLE QUANTUM-WELLS

The optical-absorption saturation of intersubband transition within the conduction band of GaAs/AlxGa1-xAs multiple quantum wells (MQW's) has been investigated. The MQW sample grown by molecular-beam epitaxy consists of 50 periods of 70-angstrom-wide GaAs wells and 178-angstrom-wide AlxGa1-xAs barriers with x = 0.25. The absorption is peaked at 9.49 mum. The infrared radiation from a tunable transversely excited atmosphere CO2 laser was to induce the transition between the lower subbands. The saturation intensity obtained is I(s) = 0. 67 MW/cm2. Using our theoretical expression for saturation intensity, we have calculated I(s) = 0.52 MW/cm 2.