US Government As Represented by the Secretary of the Army

USA As Represented by Secretary of the Navy

Arthur C Paolella

Dana J Sturzebecher

Peter R Herczfeld

Thomas P Higgins

Steven A Malone

Robert A Lux

James F Harvey

Arye Rosen

Joseph H Abeles

Roland Cadotte, Jr

Felix Schwering

Tsang-Der Ni

William D Jemison

Bahram Nabet

Milson Silva

A power divider/combiner is formed from multimode dielectric waveguides in hich energy in a single mode is translated into a plurality of modes in the multimode waveguide, each mode is separately amplified and applied to another multimode waveguide that combines the modes in phase at the output thereof.

Low loss based power divider/combiner for millimeter wave circuits

A planar antenna for microwave applications includes a supporting structure that is made using standard LTCC (low temperature co-fired ceramics) multi-layer techniques and a polyimide tape containing an adhesive at one side which is adheringly attached to the supporting structure. The body of the supporting structure defines a transmission line substrate and several of the intermediate layers define a path for microwave energy to be coupled from the transmission line substrate to the antenna. The method includes adhering the tape to the supporting structure, cutting the tape to size, and baking the tape and supporting structure in an oven at about 180.degree. C. for about 4 hours to rigidify the tape. The obtained antenna is thus protected against substrate effects such as TM mode zero cut-off frequencies.

Low-loss aperture-coupled planar antenna for microwave applications

An optical detector for determining the wavelength of an optical signal iudes a semiconductor material in the path of the optical signal having a bandgap less than the optical signal. A conductive layer is positioned on the semiconductor material and a plurality of conductive pads are also positioned on the semiconductor material to delineate individual photodetectors. The pads have a common node established by the conductive layer. The optical detector produces a plurality of photocurrents between the pads and the conductive layer in response to the optical signal which photocurrents can be measured and compared to determine the wavelength of the optical signal. A system for determining the wavelength of the optical signal includes a plurality of optical detectors numbered 1 to n positioned sequentially in the path of the optical signal. The detectors produce photocurrents which are converted into digital signals. A microprocessor receives the digital signals and determines a ratio therebetween. A memory accessible by the microprocessor relates the ratio and the nth numbered detector to the wavelength of the optical signal.

Detector for determining the wavelength of an optical signal

An FET or MESFET having a semiconductor optically transparent gate. A substrate having a doped channel placed thereon together with a source and a drain with a semiconductor gate formed therebetween may be manufactured using conventional semiconductor manufacturing techniques. The optically transparent highly doped semiconductor gate forms an n+-n junction with the n-type doped channel. This junction is modulated or changed by an optical signal causing a photovoltaic effect that reduces the barrier potential at the n+-n junction resulting in a depletion of the accumulation region. This results in increased flow of current in the doped channel. The transparent highly doped semiconductor gate increases performance of the FET or MESFET optical detector. This is an improvement over conventional metal semiconductor field-effect transistor (MESFET) technology, and can be applied to microwave monolithic integrated circuits (MMIC).

Optical field-effect transistor with improved sensitivity

An optically coupled FET comprised of bottom layer, a top layer in which FET is formed and an intermediate layer having a waveguide communicating with a grating in registration with the FET.

Optically coupled MESFET

An optical detector comprised of a MESFET having a larger than usual separation between its source and drain electrodes and a channel between the source and drain electrodes doped with carriers having a density of at least 10.sup.18 /cm.sup.3 whereby variation in the voltage of the gate electrode changes the optical gain.

Variable gain optical detector

A dual-gate self-oscillating mixer FET that is injection-locked from a remote LO frequency source. The dual-gate FET having a feedback circuit connected between the first gate port and the drain port that is tuned so that the FET can oscillate within a frequency range including a predetermined LO frequency. The FET having a remote synchronization circuit electrically connected to the FET first gate port to inject the predetermined LO frequency therein and lock the FET oscillation to that LO. Accordingly, the dual-gate FET mixes RF energy input to the second gate port with the locked LO injected in the first gate port and outputs the desired intermediate frequency through the drain port.

Optically injection-locked self-oscillating dual-gate MESFET mixer

An integrated optical intensity modulator. The modulator is an optical waveguide on a semi-insulating substrate and having a core layer for transmitting an optical signal. The modulator includes contiguous the core layer an active cladding which has a multicoupled quantum well structure. The multicoupled quantum well includes at least one pair of quantum wells separated by a barrier. The modulator further includes first and second additional claddings wherein the core layer and the active cladding are interposed between the additional claddings. A voltage source generates an electric field through the active cladding which varies the refractive index of the active cladding as a function of the strength of the electric field for modulating the optical signal.

Coupled quantum well optical intensity modulator for INP based

A tapered waveguide for transmitting optical signals from a signal source to an optical fiber is fabricated by irradiating a layer of prepolymer resin on a substrate with a converging beam of ultraviolet light, whereby the irradiated resin polymerizes into a clear, hard polymer and the resin that has not been irradiated remains in its resinous state. The unpolymerized resin is removed with an organic solvent. The variation in width of the waveguide is achieved by varying the distance between the source of the converging beam of ultraviolet light, thereby varying the diameter of the spot that is being irradiated, while simultaneously moving the source of ultraviolet light parallel to the axis of the waveguide. Variation in thickness of the waveguide is achieved by sloping the substrate.

Method of forming an improved tapered waveguide by selectively

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.

Direct optical injection locked fet oscillator

The present invention utilizes the internal photovoltaic effect of a GaAs SFET to mix an RF modulated optical signal with a microwave signal. As those skilled in the art will readily recognize, a GaAs MESFET generically comprises an n layer of GaAs (channel) deposited on semi-insulating GaAs (substrate). Source, gate and drain electrodes are then formed on the channel with the gate acting as a Schottky barrier. In this standard MESFET, the difference in doping between the channel and substrate produces a potential barrier. It has been found that when the device is illuminated, the potential barrier is reduced in the region between the source and the gate and drain and the gate. This reduced potential barrier allows more drain current to flow from the device. It has been found that this drain current photoresponse is highly non-linear with respect the gate voltage applied to the device and therefore, it may be used to mix RF modulated optical signals with microwave signals. Accordingly, the present invention uses this effect to mix an optical signal directly or indirectly delivered to the MESFET with an RF signal so as to produce an IF signal.

Method for mixing optical and microwave signals using a GaAs MESFET

An optically controlled resonant tunnel diode oscillator assembly having a esonant tunnel diode (RTD) which, when voltage biased, oscillates at a free running frequency; an optical signal delivery system, such as a light intensity modulator connected to optical fibers; and other oscillator circuitry which one skilled in the art could readily adapt to the concepts of the present invention. In operation, the free running oscillation of the RTD can be frequency modulated or can be intensity locked to the intensity modulated optical signal delivered via the optical signal delivery system.

Optically controlled resonant tunnel diode oscillator

A method and system for steering an antenna beam are provided. A light source emits light wherein at least one parameter of the emitted light is modulated. Modulated light is received by an optical detector and an analog control signal is provided by the optical detector in response to the modulated parameter. The control signal is applied to an analog-to-digital converter to convert the signal from analog to digital. The digital converter output signal is applied to a digital phase shifter for controlling the phase shift of the phase shifter and thereby steering an antenna beam according to the modulated parameter. The modulated parameter may be, for example, the intensity of the emitted light or the frequency of the emitted light. A plurality of converters and phase shifters may be provided for steering of phased array antennas.

Optical antenna beam steering using digital phase shifter control

An optical controlled attenuator circuit for controlling a microwave varie attenuator. The optical controlled attenuator circuit includes, a light source, a control connected to the light source, an optic fiber having an end coupled to the light source, a field effect transistor coupled to a second end of the optic fiber, a first inverting amplifier coupled to the field effect transistor, a second non-inverting amplifier coupled to the first amplifier means, a third non-inverting amplifier coupled to the second amplifier, a fourth inverting amplifier means also coupled to the second amplifier, and a microwave variable attenuator having first and second inputs respectively coupled to the fourth inverting amplifier and to the third non-inverting amplifier means and having an RF input and an RF output.

Optical control of a microwave switch

An optically injection locked resonant tunnel diode oscillator assembly hng a resonant tunnel diode (RTD) which, when voltage biased, oscillates at a free running frequency; an optical signal delivery system, such as a light intensity modulator connected to optical fibers; and other oscillator circuitry which one skilled in the art could readily adapt to the concepts of the present invention. In operation, the free running oscillation of the RTD can be locked to the phase and frequency of the intensity modulated optical signal delivered via the optical signal delivery system. This injection locking occurs as the modulation frequency approaches the free running oscillation frequency.

Growing community of inventors

Howell, NJ, United States of America

Arthur C Paolella