INFRARED MODULATION VIA COUPLING GRATINGS LYING ON III-V MULTIPLE-QUANTUM WELLS

We develop a theory to study the diffraction and absorption properties of a lamellar grating etched on top of a plane stratified medium whic h is an inorganic multiple quantum well made of isotropic and anise,tr opic materials. It is shown that the grating characteristics can be op timized in such a way that even when illuminated under normal incidenc e at 10.6 mu m wavelength, the multiple quantum well may absorb 40% of the incident energy. Changing the permittivity tensor of the componen ts of the superlattice by acting on the intraband transitions via an e lectrical or optical action (Stark effect for example) opens a way to infrared modulation and detection.