A modulation depth of 40% (0.7 dB/mu m) was obtained with an infrared
(10.6 mu m) modulator consisting of a stack of 50 pairs of weakly coup
led asymmetric quantum wells monolithically integrated with a quantum
well infrared photodetector. The monolithic integration is shown to be
a promising technique for the ''ac'' coupling of infrared focal-plane
arrays as well as for the direct study of the effects of electric fie
lds and charge density variations on intersubband transitions. (C) 199
6 American Institute of Physics.