Thick transparent semiconductor substrate heterojunction acoustic charge transport multiple quantum well spatial light modulator

Claim 1

A spatial light modulator, comprising: a thick semiconductor substrate, transparent to incident light; a multiple-quantum-well region, disposed above said thick semiconductor substrate, having the incident light passed therethrough, having an optical absorption threshold energy smaller than the band-gap energy of said thick semiconductor substrate and substantially equal to the energy of the incident light, and having an optical parameter which is altered in response to an electric field applied therein; a charge transport region, made of piezoelectric semiconductor material, located contiguous with said multiple-quantum-well region, and having a charge transport channel therein, for transporting charge along said charge transport channel using a surface acoustic wave, said charge applying said electric field within said multiple-quantum-well region, and for preventing the escape of charge from said charge transport channel; said thick semiconductor substrate having a thickness such that the overall thickness of said thick epitaxial semiconductor layer, said multiple-quantum-well region, and said charge transport region allows a surface acoustic wave to propagate therein; charge supply means for passing said charge to and from said charge transport channel; and surface acoustic wave means, disposed above said thick semiconductor substrate, for launching said surface acoustic wave along said charge transport channel within said charge transport region.