OPTICAL SWITCHES WITH COMBINED BRAGG REFLECTORS AND DOPING SUPERLATTICES

We discuss new studies of a multiple quantum well hetero n-i-p-i structure which combines the advantages of multiple quantum wells and doping superlattices. The structure exhibits large changes in its absorption coefficient and refractive index for intensities of only a few mW/cm2. We propose incorporating the structure into a semiconductor dielectric mirror for use as an all optical switch with very low operating intensities

High pressure measurements on AlxGa1−xAs-GaAs (x = 0.5 and 1) superlattices and quantum well heterostructure lasers

Absorption data on AIAs-GaAs and Alx Gal _ x As-GaAs superlattices (SL's) and emission data on Alx Gal _ x As-GaAs quantum-well heterostructure (QWH) laser diodes subjected to hydrostatic pressure (0-10 kbar) at 300 K are presented. Superlattice absorption data show that the confined-particle transitions, which partition and "label" the r energy band high above the band edge, all move with the same pressure coefficient of 11.5 meV /kbar. (For bulk GaAs, the pressure coefficient is 12.5 me V /kbar. ) The effect of the L indirect minima on the highest observed confined-particle transitions is small; the effect of the X minima is large. At lower pressures, QWH diodes exhibit a pressure dependence similar to that of the free (unconstrained) SL's. The data on QWH diodes demonstrate, however, a size-dependent [Lz (GaAs) < 500 A] shift in slope to a lower (8.5 meV /kbar) energy gap versus pressure coefficient at higher pressures. This change in slope can be explained by considering the effect on the light- and heavy-hole subbands of shear stresses generated within the p-n diode heterostructure