Abstract: A far infrared (FIR) to near infrared (NIR) light converter is comprised of a quantum well intersubband photodetector (QWIP) integrated vertically with a light emitting diode (LED).

Abstract: An optical switching device is comprised of an asymmetrical double barrier resonant tunnelling diode (RTD) connected in series with load resistance apparatus to a power source, apparatus for illuminating the RTD with an infrared incident light beam, apparatus for applying signal power to the RTD, and apparatus for varying the power within the RTD.

Abstract: An infrared emitting semiconductor device having a layer-shaped infrared emitting region with a superlattice structure. The superlattice structure consists of thin alternating narrow and wide wells separated by thin barriers. The narrow well has one quasibound state E'.sub.0 while the wide well has two states E.sub.0 anad E.sub.1 with E'.sub.0 being located between E.sub.0 and E.sub.1. Under proper bias, an electron in state E.sub.0 can resonately tunnel out of the well through the quasibound state E'.sub.0 to the first excited state E.sub.1 of the next wide well. This electron can then relax to the ground state E.sub.0 where it can resonately tunnel to the next wide well and repeat the process. Infrared radiation with its photon energy equal to E.sub.1 -E.sub.0 is emitted as the electrons relax from E.sub.1 to E.sub.0 in the wide wells.

Abstract: A fast, real time method and apparatus for long wavelength infrared photodetection employs a quantum well from which stored electrons are ejected by photoemission and replaced by electrons which tunnel through a barrier bounding one side of the quantum well. The photodetector comprises a semiconductor device having a quantum well layer separated from an emitter layer on one side by a first barrier layer and from a collector layer on the other side by a second barrier layer. The first barrier is higher than the second which in turn is higher than the Fermi level in the quantum well layer. Photons excite electrons in the quantum well to an excited state from which they flow over the second barrier to the collector layer. Electrons tunnel from the emitter through the first barrier to the quantum well at the rate at which they are depleted by photoemission so that the detector is suitable for use with high pulse rate digital communication signals.

Abstract: The present invention relates to a novel semiconductor heterostructure device characterized by improved coupling of tunnelling current to an electromagnetic field in the region between doped conductive layers of the device comprising a first conductive contact layer comprising a semiconductor including a dopant material, a barrier layer in juxtaposition to the first conductive contact layer comprising a semiconductor of a different material than that of the first layer to control the tunnelling current, a non-barrier layer in juxtaposition to the barrier layer comprising an undoped, semiconductor material to provide improved coupling to the electromagnetic field, a second conductive contact layer comprising a semiconductor including a dopant material, and means for applying a bias voltage potential across the device to generate photon emissions.