Abstract: Optically pumped coupled quantum well devices are disclosed. The devices store bits as carrier packets in depressions in the conduction and/or valence band(s) of a single crystal; the band between the depressions is sloped in a common direction which provides unidirectionality. The carrier packets are shifted from depression to depression by optically exciting the carriers and relying on the arrangement of depressions and band slopes; the excitation is conveniently performed by laser illumination. The depressions may be sufficiently small to discretize the energy levels and thereby permit the partitioning of the depressions into groups with each group having depressions of substantially the same energy level structure. The carriers in depressions of one group can then be selectively excited by illumination with a laser or narrow band monochromatic incoherent light source tuned to the energy level structure; this allows multiphase operation of the shifting function.

Abstract: Noise and fault tolerant devices made of cellular automata are disclosed. Preferred embodiments include cellular automata with updating rules that set a cell to a first state if more than a threshold number of adjacent cells are in the first state and with output being a state average over all cells; thus updating overcomes noise and fault induced state changes. Embodiments with cells as discrete electronic devices and with cells as quantum wells in a monolithic semiconductor body are disclosed.

Abstract: A three terminal tunneling device analogous to a field effect transistor is disclosed. Preferred embodiments include a planar quantum well (52) with a gate insulator (56) and gate (58) on one surface and with a tunneling barrier (54) and source (62) and drain (60) on the other surface. The conduction current comprises electrons tunneling from the source (62) into the well (52) and then out into the drain (60). The gate (58) bias shifts the well subband levels up and down to establish and disrupt resonance for the tunneling from the source (62) into the well (52). Other preferred embodiments include interdigitated source and drain, multiple gates, multiple wells, and floating gates.

Abstract: A light modulator and a high speed spatial light modulator (230) with each pixel (231) made of stacked quarter wavelength layers (232, 234) of heterogeneous material. Each layer (232, 234) is composed of periodic quantum well structures whose optical constants can be strongly perturbed by bias on control electrodes (240, 242). The control electrodes (240, 242) act to either remove light absorbing electrons from the layer or to inject them into each layer. The effect is to produce either a highly relecting mirror or a highly absorbing structure. The spatial light modulator (230) is compatible with semiconductor processing technology. Also, a modulator invoking the Burstein effect in the form of a stack of p-n diodes is disclosed.

Abstract: Fiber optic coupler for coupling two mutually isolated optical fibers to a third union fiber rapidly and easily. Two mechanical elements are used, the first one being a hollow cylinder with an inside diameter equal to twice the fiber outside diameter, and the second being a second hollow cylinder with an inside diameter equal to one fiber diameter and an outside diameter equal to twice the fiber diameter. The union fiber is inserted into the smaller cylinder, the two mutually isolated fibers are inserted into the larger cylinder, the empty space in the larger cylinder is filled with an index-matching cement, and the two cylinders are then pushed together. This provides a simple and economical assembly of a coupler which will work for plastic fibers, and does not require any expensive manufacturing steps. Preferably stainless steel is used for the two cylinders.

Abstract: Coupler for joining two optical fibers to a third fiber, while preserving good optical isolation between the first two fibers. The coupler is preferably formed of an approximately index-matching plastic, and the fiber ends are cemented in place. The two fibers which are to be isolted are located parallel and adjacent to each other, and their ends are glued into an elongated hole on one side of the coupler. Opposite to this hole is a second hole into which the union fiber is seated. Epoxy glue is used to connect the fibers in place. Plastic fibers are preferably used.