Abstract: A directional coupler is formed with adjacent edges of its microstrips following curved paths having reversals in curvature such as a series of sine waves or half circles.

Abstract: The coupling of optical signals to the active region of a FET having a wide source to drain spacing via an optical fiber and material having an index of refraction matching that of the fiber or the FET so as to increase the locking range when the FET is part of an oscillator circuit or to increase the change in the electrical gain of the FET caused by a change in the optical energy if the FET is an amplifier.

Abstract: One or more double barrier resonant tunneling filters are provided for electron propagation mode control in nanostructure quantum wire electron waveguides and in quantum interference devices in the waveguide.

Abstract: A circuit incorporating an infrared hot electron transistor having a common base and biasing voltages. In one embodiment, the circuit is configured to take advantage of the photovoltage amplification capabilities of the infrared hot electron transistor. In another embodiment, the infrared hot electron transistor is configured to take advantage of the photovoltaic mode of operation of the infrared hot electron transistor. The present invention can therefore be used to directly replace a photodiode used in infrared detection. The present invention additionally provides an amplified output voltage and permits direct DC coupling to a high gain operational amplifier.

Abstract: A method for producing a buried heterostructure active devices and a passive waveguide by providing a heterostructure substrate such as a superlattice having at least one planar GaAs layer and at least one AlGaAs layer adjacent to it. A single crystal germanium layer is epitaxially deposited on the superlattice substrate. A layer of gold is deposited on the germanium layer. The gold and germanium layers are imagewise patterned and selected portions etched away. The patterned substrate is encapsulated in a compatible, heat resistant encapsulating material. The encapsulated substrate is then annealed at a temperature of up to about 350.degree. C.

Abstract: A tubular structure having a transverse magnetic field that varies in eit the longitudinal direction or the lateral direction. In one embodiment, a permanent magnet tubular structure has a working magnetic field space that is partially bounded by pole pieces that reduce the height of the working magnetic field space. A laterally varying magnetic field is formed within the tubular structure. In another embodiment, a permanent magnet tubular structure is comprised of sections made of a permanent magnetic material, each section having a different remanence. The adjacent sections, having different remanence, form a linear array resulting in a longitudinally varying magnetic field gradient within the working space. The present invention has many practical applications such as in magnetic resonance imaging.

Abstract: The present invention (or multi-terminal lateral hot-electron transistor, ET) is based on a high electron mobility (hot-electron) transistor with a split-gate arrangement similar to those used in quantum wave guide devices. In the present invention, the depletion below the split gate is used to form, and control, potential barriers between the source and drain contacts. The devices, according to the present invention, exhibit pronounced SNDC which is controlled by the gate bias.

Abstract: An optically controlled oscillator circuit having an oscillator field eff transistor (FET) and having a separate light sensing quench FET. The optically controlled oscillator circuit includes, a light source, a control connected to the light source, an optic fiber having an end coupled to the light source, a quench field effect transistor (FET) coupled to a second end of the optic fiber, an oscillator FET, each FET being a GaAs multi-finger FET having drains and sources and gates, and a circuit connected in series circuit through the drains and sources of the quench FET and oscillator FET across a source of positive voltage.

Abstract: An X-band (8-12.5 GHz) amplifier comprises a bipolar junction transistor (BJT) arranged for receiving an X-band signal, amplifying the signal and providing the amplified signal to further circuitry. Input and output matching networks are advantageously provided for the BJT. Each network may have a first end for connection to a BJT and a second end for connection to a terminal, and may comprise a series connection of a first inductor, a first capacitor and a second inductor extending from the first end to the second end in that order; a third inductor connected between ground and the connection point of the first capacitor and the second inductor; and a second capacitor connected between ground and the second end. The various reactance components may be implemented on a dielectric board, for example by microstriplines and/or shaped cladding portions. An X-band oscillator may comprise the X-band amplifier described above, and a feedback circuit interconnecting an output and an input of the amplifier.

Abstract: Methods of manufacturing rings, cylinders, hemispheres and spheres having a elatively strong central working field. The manufacture of complex magnetic structures is greatly simplified by a method of cutting wedge shaped portions radially into sections, rotating the bonded sections about a radial axis prior to magnetization, magnetizing the sections in a uniform magnetic field, rotating the magnetic sections into their original positions thereby forming the resulting desired permanent magnet structure. In another embodiment, another method of making a hemispherical or spherical magnet structure using rings ground into wedge shaped portions and reassembled is disclosed. In another embodiment, a method of manufacturing a cylindrical quadrupole is disclosed whereby sections of a magic ring are removed and collapsed to form half a cylinder and combined with an analogously collapsed magic ring forming a second half cylinder and combined to form a quadrupole.

Abstract: A microwave oscillator capable of being switched into or out of the oscillating state within a fraction of the period of oscillation. The instant-on microwave oscillator permits both the generation and modulation of a microwave signal by using a single active microwave semiconductor device which is a resonant tunneling diode. The instant-on microwave oscillator circuit includes a conductive transmission line having an impedance Z.sub.O with a corresponding ground plane; and a pair of output terminals connected one on each of the transmission line and the ground plane. An impedance Z.sub.L, having an impedance value which is less than ZO, is positioned across the output terminals. A pair of input terminals is connected at the opposite end of the transmission line, one on each of the transmission line and the ground plane with a resonant tunneling diode connected across the input terminals. An impedance Z is connected to the input terminal on the biased side of the transmission line.

Abstract: A magnetic flux-enhanced control line for a superconducting flux flow transistor (SFFT). The SFFT includes a pair of superconducting electrodes which provide a voltage output, a region of weakened superconductor connecting the electrodes and a control line. The region of weakened superconductor carries a current I.sub.body and the control line carries a current I.sub.Control. The control line further has a portion thereof proximate the weakened region for providing a localized magnetic field through the weakened region as a function of I.sub.Control. The magnetic flux through the weakened region induces vortices therein which have a resistance r.sub.o. The proximate portion of the control line forms a tortuous current path whereby the magnetic flux through the weakened region is increased for increasing r.sub.o so that the output voltage of the transistor is increased without increasing I.sub.Control.

Abstract: A ferroelectric phase shifter, especially for the X-band, may be made from n elongated slab of ferroelectric material, which has a high dielectric constant that can be varied by applying an electric field. A narrow signal conductor is formed extending across a first surface of the slab, and a ground plane conductor is formed an opposite surface, forming a microstripline. An overall RF phase shifting circuit can be made by forming input and output circuits corresponding to the above-described signal conductor and interposing and connecting the signal conductor between the input and output circuits. The input and output circuits can be formed on respective, discrete substrates, with the ferroelectric slab being interposed between the substrates, or the input and output circuits can be formed on a common substrate, with the ferroelectric material inserted into a slot formed in the common substrate.

Abstract: A sensor for chemical vapor detection using a surface acoustic wave (SAW) ray that provides a means for simultaneously detecting several chemical agents. The sensor has a piezoelectric substrate and a bidirectional surface acoustic wave transducer on the substrate. Also on the substrate are several pairs of identical acoustic sensing and reference channels each on opposite sides of the transducer in a mirror image fashion. Each channel pair has a thin film capable of absorbing a chemical vapor to be monitored and a metallic surface acoustic wave grating reflector capable of receiving and reflecting surface acoustic waves through the thin film and back to the transducer. An acoustic absorber separates each channel. The reference channels are protected from ambient conditions while the sensing channels are exposed to such conditions. An RF signal is applied to the transducer causing the propagation of an acoustic signal into each of the sensing channels and reference channels.

Abstract: A dual channel flexural device is fabricated on a gallium arsenide (GaAs) bstrate that includes a pair of elongated active vibrating (GaAs) bars formed in the substrate that serve as acoustic waveguides. One of the bars serves as a reference channel, while the other bar is covered with a chemically sensitive coating and operates as a sensing channel. A pair of pseudo-surface acoustic wave (SAW) transducers serving as input and output transducers are located at each end of the bars. Each of the transducers is comprised of discontinuous U-shaped elements having dimensions and mutual separations of one half the acoustic operating wavelength formed on one side of the substrate while ground electrodes are formed thereunder on the opposite side of the substrate. When the transducers are energized, a flexural motion in the bars is set up, causing the bars to vibrate.

Abstract: A light emitting diode comprising microporous silicon of one conductivity type forming a PN junction with silicon of the opposite conductivity type and electrodes respectively connected to said regions, at least one of the electrodes being transparent.

Abstract: A multiple quantum well optical modulator comprising a multiple quantum well structure embedded in the intrinsic region of an s-i-n+ semiconductor. The s-i-n+ structure causes an electric field to be applied to the multiple quantum well structure which causes uncoupling of the el energy confined level of one layer and the x level of the adjacent layer, thereby changing the absorption of the light and causing modulation thereof.

Abstract: The present Field Effect Real Space Transistor, or FERST, is a four terminal device with S, G, C, and D representing the source, gate, collector, and drain, respectively. The S, G, and D terminals can be likened to those of the MODFET. The collector name is borrowed from other real space transfer devices. Surrounding the entire device is an oxygen implant isolation. The source and drain ohmic contacts penetrate to the 150 .ANG. GaAs channel while the collector ohmic contact does not penetrate due to its position upon an elevated submesa. AlGaAs layers are used as etch stops during processing of the device and a Schottky barrier gate is placed on an undoped layer. Channel carriers are provided by modulation doping the lower barrier of the channel. An Al.sub.0.35 Ga.sub.0.65 As layer on the upper channel side is used as a real space transfer barrier. In operation and under appropriate bias conditions, real space transfer occurs across this upper barrier and into the collector.

Abstract: A circuit for measuring capacitor properties under high DC bias voltage. A apacitor is subject to a high DC bias by a high voltage supply having low AC impedance. A triangle wave voltage is applied to the capacitor at the terminal opposite the high bias voltage. A current is thereby induced due to the voltage difference across the capacitor generated by the triangle wave. The induced current is measured and properties of the capacitor calculated therefrom. The measuring circuitry is isolated from the high DC bias voltage applied to the capacitor. Therefore, the biasing voltage applied to the capacitor is limited only by the breakdown voltage of the capacitor under test.

Abstract: A microstrip antenna capable of dual-frequency operation. The antenna comprises a microstrip having a thin, rectangular metal strip that is supported above a conductive ground plane by two dielectric layers which are separated by an air gap or other lower dielectric constant material. Conducting side walls and a rear wall extend between the ground plane and the strip. The ground plane, the strip, the walls and an opening at the front cooperate to form a rectangular resonant cavity. In essence, the cavity is surrounded by conducting surfaces except for the front opening and a small opening in the ground plane that accommodates an antenna feed. The front opening of the cavity functions as an antenna aperture through which the antenna transmits and/or receives energy. The antenna feed is a coaxial transmission line that provides a means for coupling the antenna to an external circuit. The spaced dielectric layers and the air gap produces higher-order modes which causes dual frequencies.