Optical switches and detectors utilizing indirect narrow-gap superlattices as the optical materials

An indirect narrow-gap superlattice useful as the active optical material for an optical detector, comprising:

• a first semimetal/semiconductor layer comprising a rhombohedral semimetal grown in a [111] direction on a substrate material having a (111) orientation, and a zincblende semiconductor grown in a [111] direction on said rhombohedral semimetal;
• and
• one or more additional semimetal/semiconductor layers grown on said first semimetal/semiconductor layer, each additional semimetal/semiconductor layer comprising a zincblende semiconductor grown in a [111] direction on a rhombohedral semimetal, wherein said rhombohedral semimetal is grown in a [111] direction on said semiconductor of the preceding semimetal/semiconductor layer;
• wherein each rhombohedral semimetal sandwiched between zincblende semiconductors has a thickness such that said indirect narrow-gap superlattice has a direct energy gap less than h.omega. and an indirect energy gap less than said direct energy gap.

An optical switch, comprising:

• a nonlinear medium, having a first surface, a second surface and a perimeter wall, consisting of an indirect narrow-gap superlattice comprising:
• a first semimetal/semiconductor layer comprising a rhombohedral semimetal grown in a [111] direction on a substrate material having a (111) orientation, and a zincblende semiconductor grown in a [111] direction on said rhombohedral semimetal;
• and
• one or more additional semimetal/semiconductor layers grown on said first semimetal/semiconductor layer, each additional semimetal/semiconductor layer comprising a zincblende semiconductor grown in a [111] direction on a rhombohedral semimetal, wherein said rhombohedral semimetal is grown in a [111] direction on said semiconductor of the preceding semimetal/semiconductor layer;
• wherein each rhombohedral semimetal sandwiched between zincblende semiconductors has a thickness such that said indirect narrow-gap superlattice has a direct energy gap greater than h.omega. and an indirect gap less than h.omega.;
• and
• a linear medium having a first surface, a second surface and a perimeter wall, and having a refractive index of n.sub.o ;
• wherein said nonlinear medium is embedded in said linear medium, such that said first surface of said nonlinear medium is positioned at an angle .theta. in comparison to the first surface of said linear medium.