LARGE INFRARED MODULATION DEPTH OBTAINED IN THE NORMAL INCIDENCE REFLECTION ON A GRATING-COUPLED WITH INTERSUBBAND TRANSITIONS

An infrared modulator based on intersubband transitions in GaAs/AlGaAs quantum wells, working at normal incidence, has been fabricated. The electro-optic modulation arises from electron transfer between coupled wells by applying an electric field to the device. The coupling betwe en the light and quantum wells is provided by a metal diffraction grat ing. Modulation depths larger than 60% are observed at a 8.8 mu m wave length in the nondiffracted order reflected by the modulator. The perf ormance measured at 80 K is limited by an incomplete electron transfer between wells. (C) 1997 American Institute of Physics.