Absorption Modulation in Field Effect Quantum Well Structures.

We present investigations of modulation of the absorption in InGaAs/InAlAs modulation doped single quantum well structures used as conducting channel in field effect transistors. The electron concentration can be tuned continuously from N ~ O to N ~ 6.5x10 sup (11) cm sup (-2) using the gate voltage. The effects give in situ information on the 2D-electron gas. Furthermore the total quenching of the absorption seen at the n sub z =1 edge has potential applications to optical interconnects for III-V electronics and to lightwave optoelectronic devices.