Abstract: A semiconductor diode is designed to operate at a temperature where the thermal generation of free charge carriers is negligible. The diode includes a first semiconducting layer with a sufficient concentration of first conductivity type impurities to exhibit metallic type conductivity, a second semiconducting layer with a sufficient first conductivity type concentration to create an impurity energy band and with a second conductivity type impurity concentration less than half the first, and a blocking layer between the first and second layers with a sufficiently low impurity concentration that substantially no charge transport can occur by an impurity conduction mechanism. First and second ohmic contacts are deposited on the first and second layers opposite the blocking layer. The same types of layers are used to construct transistors.

Abstract: A solid state photon detector includes a semiconducting blocking layer with sufficiently low donor and acceptor concentrations that substantially no charge transport can occur by an impurity conduction mechanism. A semiconducting buffered layer is provided with a sufficiently high donor impurity concentration to create an impurity energy band and with a sufficiently high acceptor impurity concentration that an electron cannot be injected into and drift through the layer without recombining with ionized donors. A semiconducting active layer is positioned between the blocking and buffered layers with a sufficiently high donor concentration to create an impurity energy band. The acitve layer also includes a sufficiently low acceptor impurity concentration that a photogenerated electron can drift through the active layer without recombining with ionized donors.

Abstract: An antireflective optical film exhibits a quintic refractive index profile with an initial refractive index n.sub.L as close as possible to the refractive index of the incident medium and a final refractive index n.sub.H substantially equal to the refractive index of the substrate. The refractive index profile of the film may be defined by the relationship:n(x)=n.sub.L +(n.sub.H -n.sub.L) (10 (x/T).sup.3 -15( x/T).sup.4 +6( x/T).sup.5)where N(x) is the refractive index of the film at a depth x in the film relative to the incident surface of the film and T is the thickness of the film. The film may also be fabricated as a plurality of layers, with each layer substantially thinner than wavelengths within the spectral band. Each layer within the plurality is divided into a sublayer pair, including a first sublayer with the refractive index n.sub.L and a second sublayer with the refractive index n.sub.

Abstract: A random access memory circuit for use with positive and negative supply voltages, a read enable line, an output line, and write "1" and "0" lines includes first, second, third, and fourth level shifting diodes. A first input isolation diode is connected between the write "1" line and the first level shifting diode. A second input isolation diode is connected between the write "0" line and the cathode of the third level shifting diode. The drain of a first write FET is connected to the anode of the third diode, the source is connected to the read enable line, and the gate is connected to the cathode of the second level shifting diode. A second write FET has its drain connected to the anode of the first level shifting diode, its source connected to the read enable line, and its gate connected to the cathode of the fourth diode. An output buffer FET is connected by its source to the read enable line, by its gate to the cathode of the fourth diode.

Abstract: Disclosed is a blocked-impurity-band detector, including an active layer which is doped with a sufficient amount of either a donor or an acceptor impurity that significant charge transport can occur in an impurity band in addition to the charge transport of electrons in the conduction band of the layer and of holes in the valence band of the layer. A blocking layer is disposed on the active layer and contains a sufficiently low concentration of impurities that significant charge transport cannot occur in the blocking layer except by means of electrons in the conduction band of the layer or holes in the valence band of the layer. First and second electrodes are provided for applying a bias potential across the active and blocking layers.

Abstract: An optical filter includes a first polarizer for transmitting light having a first polarization direction and a first birefringent element for receiving the light transmitted by the first polarizer. A second birefringent element, of a different material having a different birefringence, receives the light transmitted by the first element, while a second polarizer receives the light transmitted by the second element and transmits the portion having a second polarization direction. The birefringences and the thicknesses of the elements are arranged to effect a predetermined amount of net phase retardation, preferably zero, for light of a wavelength .lambda. in traversing the first and second elements.

Abstract: A thermal detector array includes a substrate layer with a pyroelectric layer attached to the substrate, a plurality of detector regions being defined in the pyroelectric layer by openings through the layer. An array of cavities in the substrate surface separates the detector regions from the surface. First and second electrodes are placed on opposite sides of each detector region or on a single side in a coplanar embodiment. The array is joined to a signal processing device by means of corresponding metallic contacts on the pyroelectric layer and the processing device.

Abstract: Disclosed is an apparatus for removing electromagnetic energy at a wavelength .lambda. from a beam of electromagnetic energy. Included is an electro-optically tunable Fabry-Perot filter, with an electro-optic crystal having parallel incident and exit surfaces, a first transparent electrode on the incident surface, a second transparent electrode on the exit surface, an incident reflecting layer, and an exit reflecting layer. A detector produces an electrical signal in response to the electromagnetic energy transmitted by the filter. A lock-in amplifier receives the electrical signal and outputs to a control amplifier which also receives as an input a source of alternating current. A high voltage amplifier receives the output of the control amplifier and applies its output across the electro-optic crystal.

Abstract: Disclosed is an optical bandpass filter for transmitting light in a narrow band around the wavelength .lambda..sub.c, including a first series of layers, each of thickness t, having a refractive index n.sub.1 and a second series of layers, each of thickness t, having a refractive index n.sub.2 and alternating with the first series. The thickness t is selected so that t=.lambda..sub.c /4n.sub.c and .vertline..DELTA..vertline.>.pi..vertline.D-1/.lambda..sub.c .vertline., where ##EQU1## and n.sub.c is the common value of n.sub.1 and n.sub.2 at the wavelength .lambda..sub.c. Also disclosed is a filter with each succeeding layer in the first and second series thicker than the preceding layer. The thickness of the thinnest layer is .lambda..sub.1 /4.sub.n and the thickness of the thickest layer is .lambda..sub.2 /4n Cos .theta., where .lambda..sub.1 is the minimum wavelength to be reflected by the filter, .lambda..sub.2 is the maximum wavelength, n=(n.sub.1 +n.sub.2)/2, and .theta.

Abstract: Disclosed is an optical filter for selectively transmitting light in a passband at the wavelength .lambda., including an initial polarizer with a polarization direction perpendicular to a beam path and a final polarizer spaced from the initial polarizer along the path and having the same polarization direction. A birefringent element is positioned between the polarizers with an optic axis perpendicular to the path and rotated with respect to the polarization direction, the element having a birefringence which is zero at the wavelength .lambda.. Lyot-Ohman and Solc embodiments of the filter are also described.

Abstract: Disclosed is a surface acoustic wave interferometer, including a substrate on which are disposed a first reflector and a second reflector so as to define a multimode resonant cavity therebetween. A third reflector is positioned on the substrate so that a single mode resonant cavity is defined between the second and third reflectors. An input transducer generates surface acoustic waves in the single mode cavity, while an output transducer detects the interference between surface acoustic waves in the multimode and single mode cavities. A base is rigidly affixed to the substrate in the region of the single mode cavity so that a force applied to the substrate will alter the surface acoustic wave propagation characteristics within the multimode cavity.

Abstract: Disclosed is a hybrid Schottky barrier focal plane, which includes a transparent semiconducting detector substrate of a first conductivity, with an array of detector groups disposed on the detector substrate, each group including a plurality of Schottky barrier detectors. An output contact is provided on the detector substrate for each of the detector groups. A field effect transistor for each detector includes a source region of a second conductivity type in the detector substrate and connected to the detector, a drain region of the second conductivity type in the detector substrate over the source and drain regions for controlling the connection between the source region and the drain region. An array of output contacts are disposed on a semiconducting multiplexer substrate, which also includes a charge coupled circuit for converting parallel signals from the input contacts to a serial output signal.

Abstract: Disclosed is a surface acoustic wave filter based on a ferroelectric crystal having a plurality of ordered domains of alternating polarity. An output interdigital transducer, with at least one pair of electrodes, is deposited on a surface of the crystal so that each of the electrode pairs corresponds to one of the ordered domains, and an input interdigital transducer is oriented on the surface to direct a surface acoustic wave toward the output transducer. In addition, sources of both positive and negative electrical potential may be provided, with a switch for each output electrode pair to selectably apply either the positive or the negative potential to that pair.

Abstract: Disclosed is a multiple-quantum-layer detector for responding to photons having a predetermined amount of energy. The detector includes a purality of parallel layers of a first semiconducting material having a first conduction band energy level, with a plurality of layers of a second semiconducting material parallel to the first layers and having a second conduction band energy level differing from the first conduction band energy level by no more than the predetermined energy. The second layers alternate with the first to establish a plurality of parallel heterojunctions. First and second electrodes are provided for applying an electric potential across the alternating layers.

Abstract: Disclosed is an electromagnetic acoustic transducer for use with electrically conductive objects. The transducer includes an electromagnet for establishing a static magnetic field directed into the object in a first region and directed out of the object in a second region. A meander coil for inducing eddy currents in the object when an alternating current is applied to the coil includes a first serpentine printed circuit on a first side of a printed circuit board and a second serpentine printed circuit on a second side of the board. The source and the coil are so oriented that the vector product of the field and the eddy currents produces an instantaneous force field in the object which is periodically alternately oriented.

Abstract: An apparatus for generating acoustic waves of wavelength .lambda. in an electrically conductive object includes an electromagnetic acoustic transducer, with a source of magnetic flux for producing a magnetic field in the object, a first periodic coil within the field, and a second periodic coil within the field and offset from the first coil by .lambda./4. A first port of a four port hybrid is connected to the first coil and a second port is connected to the second coil, with a 90.degree. phase delay element interposed between the first port and the first coil. A signal generator provides an input signal at a frequency corresponding to .lambda., with a transmitter for applying the signal to either a third or a fourth port of the hybrid to generate a unidirectional wave in one of two opposite directions. An apparatus for detecting acoustic waves includes a first receiver connected to the third port and a second receiver connected to the fourth port.

Abstract: Disclosed is a logic circuit with a plurality of AND logic elements, each including a plurality of Schottky diodes with each cathode connected to a logic input and the anodes connected in common to establish an AND output. A diode pull up FET is provided for each AND output, with the source connected to the AND output, the gate connected to the source, and the drain connected to a source of positive bias potential. An OR logic element includes a plurality of Schottky diodes with each anode connected to one of the AND outputs and the cathodes connected in common to establish an OR output, while a diode pull down FET has its drain connected to the OR output, with the gate connected to the source and the source connected to a source of negative bias potential. A level shifting diode is placed between the OR output and the pull down FET. An output FET is connected through its gate to the drain of the diode pull down FET, with the source connected to ground and the drain providing a logic output from the circuit.

Abstract: Disclosed is an acoustic transducer which includes a pressure tight vessel with a window in the vessel which is transparent to acoustic wave energy. A gas is disposed within the vessel, while an electromechanical transducer is located within the vessel at an antinode for a resonant wave of the gas. A port communicates with the interior of the vessel, with a pressure control coupled to the port and to a source of the gas for controlling the pressure of the fluid within the vessel.

Abstract: A broadband electromagnetic acoustic transducer is disclosed for use with an electrically conductive object. The transducer includes a source of magnetic flux for establishing a static magnetic field in the object and an electrical conductor for inducing eddy currents in the object when an alternating current is applied to the conductor. The magnetic field and the conductor are oriented so that the vector product of the magnetic field and the eddy currents produces an instantaneous force field in the object which is periodically alternately directed with a logarithmic periodicity. The source of magnetic flux may be provided by a plurality of alternately oriented magnets aligned along a propagation direction. Alternatively, the conductor may be a serpentine conductor with a plurality of parallel elements which are perpendicular to a propagation direction, the ratio of adjacent spacings between the elements being constant.

Abstract: Disclosed is an integrated dual gate switch which is fabricated on a semi-insulating GaAs substrate. A metallic input line is deposited on the substrate and coupled to an ion implanted n-type region in the substrate through a first ohmic contact. A metallic output line is spaced from the input line and coupled through a second ohmic contact to the n-type region. A first metallic gate is deposited on the substrate between the input and output lines, while a second metallic gate is deposited between the first gate and the output line. A first capacitive coupling between the input line and the first gate includes a first metallic conductor deposited on the substrate and overlapping portions of the input line and first gate, and a first dielectric layer between the first gate and the first conductor. A similar second capacitive coupling between the output line and the second gate includes a second metallic conductor and a second dielectric layer.