The results of investigations of quantum-well-based excitonic light mo
dulators, operating in the transmission and reflection modes, are repo
rted. The characteristic features of the optical spectra and the degre
es of light modulation in the structures are investigated. It is shown
that to increase contrasts substantially the modulators should be use
d in a Fabry-Perot interferometer. (C) 1996 American Institute of Phys
ics.