Multiple quantum well optical nonlinearities: bistability from increasing absorption and the self electro-optic device

Abstract

This paper briefly reviews the nonlinear optical and electro-optical properties and applications of GaAs—AlGaAs multiple quantum wells, all of which are compatible with laser diodes or semiconductor electronics or both. They show large nonlinear absorption and refraction (associated with their strong room-temperature exciton resonances) applicable to all-optical devices. They also show large electroabsorptive effects, some of which are unique to the quantum wells at any temperature, which are so strong that optical modulators can be made with micrometre dimensions. A new class of optical bistability (due to increasing absorption) is also reviewed; combination of this with the electroabsorptive effects enables a new mirrorless optical switch called a Self Electro-optic Effect Device (SEED), which sets a new standard for optical switching energies, with energy densities reduced by a factor of six by comparison to even the best resonant cavity devices.