USA As Represented by Secretary of the Navy

US Government As Represented by the Secretary of the Army

Drexel University

Rca Inc.

Other

F&h Applied Science Associates, Inc.

Peter R Herczfeld

Arthur C Paolella

Arye Rosen

Vincent Michael Contarino

Yifei Li

William D Jemison

Linda Mullen

Joseph H Abeles

Afshin S Daryoush

Steven A Malone

David K Yoo

Milson Silva

Linda J Mullen

Amarildo Jesus Cavalheiro Vieira

A linear phase demodulator/down-converter comprises an optical amplitude modulator for modulating the amplitude of an optical input signal, a photo-detector, a loop filter and an optical phase modulator provided with a light source. The optical phase modulator/down-converter provides optical down conversion, optical up conversion, or a combination thereof. The photo-detector can be a balanced photo-detector. Linear phase demodulation and/or down conversion is performed completely in the optical domain.

Optical domain frequency down-conversion of microwave signals

An attenuating counter-propagating (ACP) optical phase modulator introduces zero propagation delay. An optical field is modulated by an electromagnetic field. Within the ACP modulator, the optical field is propagated in an opposite direction to the propagation direction of the electromagnetic field. The electromagnetic field is attenuated within the ACP modulator. In an example embodiment, the length of the modulator is greater than the attenuation length of the electromagnetic field.

Attenuating counter-propagating optical phase modulation

A hybrid lidar-radar system for detecting the presence of objects, such as cancerous tumors, within tissues by detecting reflected signals from the tissue and discriminating the information related to the cancerous tumor from the undesirable backscattering of light created by the tissue itself. The hybrid lidar-radar system utilizes continuous wave light that is preferably modulated at frequencies up to 60 GHz. The present invention filters the return signals from the tissue at a subcarrier modulation frequency so as to reject erroneous information contained in scattered lights, while at the same time retaining the coherent, unscattered and modulated light information so as to provide for an accuracy detection of tumors within tissues.

Hybrid lidar-radar for medical diagnostics

A chirp signal source includes first and second lasers formed on a solid-state chip or substrate. Each of the lasers has a resonator or cavity which incorporates or includes electrooptic material which changes refractive index in response to an electric field. The lasers are pumped, and the resulting laser beams are coupled to a light-to-electric converter which combines the light beams to generate an electrical difference frequency. The change in refractive index allows the lasers to be swept or chin,ed at a much higher rate than thermal or piezoelectrically operated lasers. This structure has the advantages of tending to reduce temperature effects on the difference frequency. It has the further advantage of a high sweep rate, which can be used to improve the signal-to-noise ratio. A radar or lidar ranging system according to an aspect of the invention uses multiple solid-state lasers, which are thermally coupled together.

Multiple laser source, and systems for use thereof

A modulated LIDAR system is disclosed, in which a laser for generating an tical carrier signal and a microwave generator for generating a coded microwave signal are provided. A modulator is further provided for modulating the carrier signal with the microwave signal, whereby a modulated signal is generated. A method of detecting a reflective surface is also disclosed, in which an optical carrier signal is generated, the carrier signal is modulated with a coded microwave signal, the modulated signal is reflected off of a reflective surface and the reflected signal is recovered.

Modulator LIDAR system

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

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

An optically controlled active impedance element particularly suited to se as a tuneable inductive element for a microwave oscillator is disclosed. The optically controlled active inductive element is comprised of a circuit arrangement, preferably consisting of MESFET devices which exhibit a composite inductive characteristics, and whose inductance may be determined and controlled by direct illumination impinging on the MESFETs. The optically controlled active inductive element lends itself to being adapted to monolithic microwave integrated circuit (MMIC) applications and may find use in a wide variety of microwave circuits. Also disclosed, is an embodiment which uses the optical controlled active impedance element, in a prescribed manner, to serve as a tuneable capacitor for use in various microwave circuits.

Optically controlled active impedance element and filters employing the

An optically controlled active impedance element particularly suited to se as a tuneable inductive element for a microwave oscillator is disclosed. The optically controlled active inductive element is comprised of a circuit arrangement, preferably consisting of MESFET devices which exhibit a composite inductive characteristics, and whose inductance may be determined and controlled by direct illumination impinging on the MESFETs. The optically controlled active inductive element lends itself to being adapted to monolithic microwave integrated circuit (MMIC) applications and may find use in a wide variety of microwave circuits. Also disclosed, is an embodiment which used the optical controlled active impedance element, in a prescribed manner, to serve as a tuneable capacitor for use in various microwave circuits.

Optically controlled active impedance element particularly suited for a

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 gain control circuit for controlling the gain of a GaAs MMIC dributed amplifier having a dc gain control is provided. Variable intensity light from a controlled LED is directed to the surface of a GaAs multi-finger FET by means of an optical fiber. The FET is gate biased to a point near pinch-off to maximize its light sensitivity and the drain and source of the FET are serially connected with a fixed resistance in a dc voltage divider circuit so that the output of the voltage divider circuit changes as a function of the change in light intensity of the LED. A MMIC operational amplifier connected in an inverter mode is coupled between the output of the voltage divider circuit and the dc gain control of the distributed amplifier to control the gain of that amplifier.

Optical gain control of GaAs microwave monolithic integrated circuit

An optically controlled phased array antenna system and method of operating same utilizing fiber optic transmission lengths and controlled piezo-electric crystals or equivalent elements to introduce predetermined time delays into each light signal by controlling the respective length of each fiber optic link. The light carrying fibers are wrapped around the respective crystals in accordance with a pattern to introduce time delays corresponding to the amount of stretch given to the fiber by the energized crystals. Beam scanning is achieved by controlling the matrix of crystals to introduce appropriate time delays into the optical signals which drive the respective antenna elements.

Optically controlled phased array system and method

The characteristics of antennas are modified by photosensitive electrical elements connected to the radiating elements. The photosensitive elements are biased by light, by direct electrical bias, or both. The photosensitive element may be a PIN diode. The bias may be applied by general illumination or conducted by a fiber optic cable.

Light controlled antennas

A TEM-mode transmission line such as a microstrip or coplanar line includes a pair of conductors, at least one of which is elongated. A semiconductor junction or junctions are coupled across the conductors. If a single junction is used, the junction may be laterally elongated or distributed. If discrete semiconductor junction devices are used, plural devices may be coupled across the transmission line. The capacitance of the junction(s) controls the phase shift imparted by the transmission lines to AC signals traversing the line. The capacitance of the semiconductor junctions in controlled by light coupled into the junction region. The light is coupled to the junction region by fiber-optic cables or by means of light illuminating the junction.

Growing community of inventors

Philadelphia, PA, United States of America

Peter R Herczfeld