Abstract: An infrared hot-electron transistor comprising a doped multiple quantum well structure as an infrared radiation sensitive unit, and an electron energy filter as a dark current reduction unit. Infrared radiation incident on the device gives rise to intersubband absorption. After having absorbed an infrared photon, each photoelectron is one photon energy higher in energy than that of the dark electron, and hence can be separated by an electron energy filter. The transistor consists of three terminals, each of them has an indispensable function. The emitter supplies electrons, the collector collects photoelectrons, and the base provides drainage to the unwanted dark electrons.

Abstract: A multicolor infrared detection device comprising a number of doped quantum ell structural units. Each unit consists of a thick well and a thin well separated by a thin barrier. This arrangement produces strong coupling. Infrared radiation incident on the device gives rise to intersubband absorption. For each transition a photosignal results which allows the detection of a plurality of incident frequencies.

Abstract: A permanent magnet structure comprising a linear array of hollow cylindrical flux source structures nested one within another about a common central axis. Each HCFS structure is free to displace linearly parallel to the central axis or to rotate about the axis. The array may be arranged by appropriate mechanical adjustment to provide periodic magnetic structures suitable for use as a wiggler or a twister.