US Government As Represented by the Secretary of the Army

Weimin Zhou

Mitra Dutta

Jagadeesh Pamulapati

Paul H Shen

Ming-Chiang Li

Hongen Shen

David M Mackie

Paul W Cooke

James P Cahill

Michael R Stead

Olukayode Okusaga

Sang-Yeon Cho

Sang-Yen Cho

An optoelectronic device apparatus using active, frequency-selective metasurfaces to achieve retroreflection at a pre-determined single frequency and optionally provide signal modulation on the reflected light beam. The apparatus may use several active, frequency-selective metasurfaces to replace traditional optical lens and mirrors.

Metasurface-based active retroreflector

Time delay devices for producing tunable time delays in optical signals. Cascades of the time delay devices can be used for beam steering in phased-array antennas. The time delay may be produced by selecting a time delay between an input and output of the time delay device from any of the time delay obtained by all four-port switches of the time delay device being in an OFF state and time delays obtainable by switching any one of the four-port switches to an ON state; and producing the selected time delay between the input and output of the time delay device by performing any of avoiding an application of an electrical control signal to any of electro-optic switch elements of the time delay device and applying the electrical control signal to one of the electro-optic switch elements that corresponds to a four-port coupler corresponding to the selected time delay.

True time delay circuit based on an optical waveguide switching array for RF phased array antenna beam steering

An oscillator system includes a laser source; a high-Q electro-optical oscillator to generate a high-Q electro-optical oscillator signals having oscillator frequencies; and an environment-insensitive resonator including ENZ metamaterials. The resonator receives a laser from the laser source and generate a feedback signal to lock the oscillator to reduce a phase/frequency noise in the oscillator. An optical system also includes a high-Q electro-optical oscillator to generate a high-Q electro-optical oscillator signal having oscillator frequencies; an environment insensitive signal delay waveguide having an EMNZ metamaterial such that the signal delay waveguide delays the high-Q electro-optical oscillator signal and generates a delayed signal; and a phase-lock circuit to receive the delayed signal from the signal delay waveguide and provide an electrical feedback signal to the oscillator.

Stabilizing a precision electro optical oscillator clock using an environmentally insensitive metamaterial device

Systems, methods, architectures, mechanisms or apparatus for receiving and storing electromagnetic pulses using photonics includes a transmission unit transmitting electromagnetic pulses; an antenna receiving electromagnetic pulses reflected from a target; an optical recirculation loop for storing replica received electromagnetic pulses; and a processor for extracting target related phase information from the replica received electromagnetic pulses.

RF-photonic pulse doppler radar

An architecture for an optoelectronic oscillator uses Stimulated Brillouin Scattering (SBS) to seed, filter and amplify the oscillation signal in an overlapped oscillator loop for both a RF modulated optical sideband and a SBS signal. By phase matching the RF modulated optical sideband generated by SBS with the SBS signal, the feedback will collapse the bandwidth of the SBS signal and in turn the bandwidth of the Brillouin frequency signal, which also serves as a filter to filter out multiple undesired OEO loop modes. The embodiments herein result in reduced phase noise and increased stability.

Opto-electronic oscillator with stimulated Brillouin scattering feedback

RF-photonic system for acoustic and/or vibrational sensing using optical fiber and method thereof

An apparatus for generating a frequency spectrum of an RF signal comprising a gate switch for generating a series of pulses from a laser of wavelength lambda modulated by an input RF signal, a first fiber optical loop for circulating a first percentage of a first pulse of the series of pulses from the gate switch, for a predetermined number of cycles n where each cycle takes time t, a second fiber optical loop for conducting a second percentage of the first pulse for predetermined number of cycles 'k', where each cycle takes time t, where t*k=t*n, a first switch with a first state for coupling the first pulse from the gate switch to a coupler, the coupler coupling the first pulse into the first fiber optical loop and tapping replicas of the pulse from the first fiber optical loop, and a second state for coupling the second percentage of the first pulse to the coupler to increase intensity of the tapped replica pulses, a processor for correlating the replicas of the pulse with each other to produce a set of data points comprising a plurality of multiplexed correlated pulses and transforming the data points into a channelized frequency spectrum of the input RF signal.

Method and apparatus for analyzing the spectrum of radio-frequency signals using unamplified fiber optic recirculation loops

A method and apparatus for providing RF-photonic filtering link. Specifically, one embodiment is an apparatus comprising a radio frequency (RF)-photonic filter for filtering an RF signal, where the RF-photonic filter comprises a loop comprising an electro-optical modulator, an optical fiber, a photo detector. Another embodiment is a method of operating an RF-photonic filter comprising applying a reference signal to the RF-photonic filter; selecting a reference frequency for the RF-photonic filter upon the RF-photonic filter locking to the reference frequency, disconnecting the reference signal; and applying an RF input signal to the RF-photonic filter to lock the RF input signal to the RF-photonic filter.

Method and apparatus for providing radio frequency photonic filtering

An apparatus comprising a fiber optical loop for conducting a first and a second pulse having a corresponding first and second wavelength, a first splitter for separating the first and second light pulses in the optical loop into a first and second light path to introduce a predetermined time delay between the first and second light pulses, a coupler for tapping a replica of the pair of light pulses from the loop, an auto-correlation module, coupled to the coupler, for correlating the replica of the pair of light pulses with each other to produce a set of data points comprising a plurality of multiplied and correlated pair of pulses and a transform module, coupled to the auto-correlation module, for transforming the data points into a channelized frequency spectrum.

Method and apparatus for analyzing the spectrum of radio-frequency signals using a fiber optic recirculation loop

An electro optical scanning phased array antenna having a laser which generates a pulsed output. A microwave source has an output which amplitude modulates the optical output from the laser through an optical modulator. An optical loop circuit has an input connected to an output from the optical modulator and a variable time delay element. The optical loop circuit generates a plurality of modulated optical pulses at equidistantly spaced time intervals from each other at an output from the loop circuit. These time intervals vary as a function of the variable time delay element and a control circuit controls the time delay attributable to the variable time delay element. An antenna array includes end elements while a circuit converts the optical output pulses from the optical loop circuit to radio frequency signals electrically connected to the elements of the antenna array.

Electro optical scanning phased array antenna for pulsed operation

An apparatus comprising a dispersive fiber optical loop for delaying a first and second sideband, relative to each other, of a light modulated by a radio frequency signal to create a pair of pulses, a coupler for tapping a replica of the pair of pulses from the loop; and an auto-correlation module, coupled to the coupler, for correlating the replica of the pair of pulses with each other.

Method and apparatus for detecting radio-frequency signals using a dispersive fiber optical loop

A semiconductor hollow-core waveguide using high-contrast gratings or photonic crystal claddings and a method of manufacturing the same includes providing a layered semiconductor structure; creating an etching mask pattern over the layered semiconductor structure; performing a combined cycled directional etching process on the layered semiconductor structure in one sequence and in one lithography level to create a 3-dimensional waveguide structure; and creating a hollow air core in the layered semiconductor structure by removing to define a shape of the waveguide. The etching process comprises vertically etching a series of deep trenches on the layered semiconductor structure with precise control and varying the width of the trench. Furthermore, the hollow air core is created by removing a portion of the sacrificial material located in the center of the waveguide and under the waveguide.

Semiconductor hollow-core waveguide using photonic crystal gratings

An apparatus and method for receiving electromagnetic waves using photonics includes a transmission unit transmitting electromagnetic waves in intervals; a time delay unit coupled to the transmission unit and controlling the transmission unit to transmit the electromagnetic waves in the intervals; an antenna receiving the electromagnetic waves reflected from the target; an interferoceiver coupled to the antenna and receiving the electromagnetic waves from the antenna, the interferoceiver comprising an optical recirculation loop to produce replica electromagnetic waves; and a computer identifying the target from the reflected electromagnetic waves.

Apparatus and method for receiving electromagnetic waves using photonics

An multi-beam multifunction electro optical scanning antenna having a first variable wavelength tunable laser having an output wavelength variable within a first range and a second variable wavelength tunable laser having an output wavelength variable within a second range, different from the first range. The outputs from both lasers are modulated by independent microwave sources and the modulated outputs from both lasers are combined by an optical combiner into a combined output signal. An antenna array includes a plurality of radiators and a photodetector is associated with each radiator which converts the combined optical output from the lasers to microwave signals. Beam splitters divide the combined output signals to each of the antenna radiators while first and second wavelength-dependent time delay elements are optically connected in series between each sequential beam splitter. Each first time delay element is operable within the first wavelength range, while each second time delay element is operable within the second wavelength range. The antenna can generate two or more RF microwave beams simultaneously and independently scan/steer them.

Electro optical scanning multi-function antenna

A method for constructing a reconfigurable photonic band gap device having a substrate and a crystal membrane with a lattice structure having its ends attached to a substrate so that a midportion of the lattice membrane is spaced upwardly from the substrate and forms a chamber therebetween. A bridge is disposed in the chamber between and separated from both the lattice membrane midportion and the substrate. At least one post is attached to the bridge and aligned with at least one hole in the lattice so that movement of the bridge relative to the lattice varies the degree of insertion of the post relative to its associated hole to vary the photonic band gap behavior of the device.

Growing community of inventors

Rockville, MD, United States of America

Weimin Zhou