Abstract: An interferometric switch for spatially switching either linearly polarized or unpolarized externally derived beams of substantially coherent light includes an optical input unit for dividing an externally derived light beam into a constituent beam pair. An optical phase modulating device includes a nematic liquid crystal pixel for selectively shifting the relative phase of the constituent beam pair. An output unit cooperates to combine respective components of the constituent beam pair along coincident collinear paths so as to form a respective output light beam directed along a selected one of first and second output axes, according to the relative phase imparted by the phase-modulating device. The phase modulating device may comprise a cascading arrangement of pixel stages which can respectively provide a selected incremental phase-shift to each constituent beam passing therethrough.

Abstract: An optical communications system includes apparatus for interferometric signaling in which light signals are propagated from a first location so as to form at least one predetermined interference pattern at a second location remote from the first location and then the received light signals are demodulated at the second location. The apparatus includes a substantially coherent light source and a plurality of adjacent, substantially coplanar optical modulators in the path of the emitted light.

Abstract: An optical signal processing system includes a number of optical time delay units to generate differentially time-delayed optical signals. Each optical time delay unit includes at least an in put polarizing beam splitter (PBS) system having an input system Thompson prism and an output PBS system including an output Thompson prism. Each Thompson prism has a high extinction ratio and is positioned to act as a polarizing beam splitter, providing a high signal to noise ratio optical signal processing system. Selectively polarized light beams are deflected by the polarizing beam splitters onto predetermined paths that cause the respective light beams to be differentially time delayed dependent on the path that they follow through the optical signal processing system.

Abstract: An interferometric optical switching device for switching substantially coherent light beams includes a plurality of interferometric switching cells arranged in matrix form. Each interferometric switching cell is independently controllable to selectively direct received light beams along at least a selected one of two axes. The device can be three-dimensionally expanded to increase the number of ports to which the light beams can be selectively switched, in which case the matrices can share integrally constructed interferometric switching cells. The device is further capable of providing bidirectional communication between predetermined ones of the ports thereof.

Abstract: A compact optical switching unit includes a spatial light modulator coupled to a delay assembly such that incident light beams are respectively selectively directed along either a direct path or a delay path dependent on the linear polarization of the light beam. The delay assembly includes a light deflection device, such as a polarizing beam splitter, coupled to a delay path apparatus, such as mirror prisms or fiber optic cable. A compact and readily fabricated cascade of optical switching units includes polarizing beam splitter blocks and polarization rotation switch blocks, a portion of which constitutes the polarizing beamsplitters and spatial light modulators in respective optical switching units sequentially optically coupled. Delay path apparatuses disposed along an axis orthogonal to both the axis of beams passing along a direct path through polarizing beam splitter switches on the direct path and the axis between respective optical switching units result in a compact optical architecture.

Abstract: An optical transversal filter includes a processing system having a light source adapted to be modulated by an input electromagnetic signal and generate a plurality of collimated optical signals, a cascade of optical time delay units sequentially coupled to act upon the collimated optical signals passing from the light source to selectively differentially time delay respective ones of the optical signals, an optical trimmer device coupled to receive the differentially time delayed optical signals and to selectively attenuate respective ones of those signals, and a filter output assembly which receives and sums the optical signals from the trimmer device optically and converts the sum to a corresponding filtered electrical signal, or alternatively, converts the respective optical signals to electrical signals and electrically sums the signals.

Abstract: A compact optical switching unit includes a polarization independent beamsplitter switch (PIBS) coupled to a delay path apparatus such that incident light beams are respectively selectively directed along either a direct path or a delay path dependent on the the manipulation of the polarization of polarized constituent light beams in the PIBS. The delay path apparatus is typically a mirror prism or fiber optic cable disposed such that light deflected onto the delay path traverses a longer distance than light passing along the direct path and thus a particular light beam can be selectively time delayed by controlling the PIBS to direct the beam into desired delay paths in a cascade of optical signal switching units. A compact and readily fabricated cascade of optical switching units includes PIBS blocks, a portion of which constitutes the PIBS in respective optical switching units sequentially optically coupled.

Abstract: A compact, stable, and optically efficient two dimensional spatial light modulator-based electro-optical control system for large (>1000 elements) phase-based phased array antennas uses two externally phase-locked lasers to generate respective pluralities of first and second light beams that are respectively mutually orthogonally polarized. Respective ones of the first and second light beams are combined to pass along collinear and coincident paths to form a plurality of combined light beams. The frequency difference between the first and second light beams which form the constituent beams in each combined beam cause an interference pattern that, upon heterodyne detection of the optical signal and conversion to an electrical antenna drive signal, provides control of the carrier frequency for driving the antenna.

Abstract: A liquid crystal and acousto-optic based control system for phased array antennas provides independent control of scanning along two axes of the antenna. The optical control system includes a laser source providing polarized laser beams processed in an in-line interferometric optical architecture that uses two acousto-optic deflectors (AODs) driven by separate sidebands of a microwave signal that is a mixture of a drive frequency corresponding to the desired carrier frequency and a variable control frequency for determining a selected sideband frequency. The AODs and associated polarization rotators generate a plurality of optical signal pairs, each pair having one first order positive doppler shifted light beam deflected by a first sideband drive signal and one first order negative doppler shifted light beam deflected by a second sideband drive signal, the positive and negative doppler shifted beams being respectively orthogonally linearly polarized and traveling along almost collinear paths.

Abstract: A phased array antenna system having an optical signal processing system includes a number of optical time delay units to generate differentially time-delayed optical signals. Each optical time delay unit is configured to generate a time delay through the use of either an optical fiber or free-space optical propagation delay assembly. Differentially time delayed optical signals are generated by controlling, with a spatial light modulator, the polarization of each light beam entering each time delay unit so that each respective light beam is deflected along either a direct path or a delay path dependent on its linear polarization. Each time delay unit includes an imaging system having a selected imaging ratio, with spherical lenses disposed in the delayed and direct light paths of the unit to provide imaging between the spatial light modulator planes. High extinction ratio polarizers are positioned in each of the delayed and direct paths. Spatial filters are further disposed in each spherical lens pair.

Abstract: An optical control system for a phased-array antenna system employs a time-multiplexed optical control architecture to provide very fast (a few hundred beams per second) antenna beam scanning using slow (milliseconds) response spatial light modulators in two optical signal processing channels. In each channel a cascade of relatively slow switching speed nematic liquid crystal cell spatial light modulators and associated free space delay units or fiber optic delay cables are disposed to receive transmit or receive optical input signals comprising a plurality of light beams. The control voltages applied to the spatial light modulators determine the paths of the light beams through the cascade and the differential time delay imparted to the light beams in the input optical signal. High speed 90.degree.

Abstract: A microdynamical optical switch includes a piezoelectric actuator disposed on a substrate, a mirror securely mechanically coupled to the actuator, an input connection port, and a plurality of output connection ports. The actuator displaces the mirror along a mirror displacement path such that the mirror, which is oriented at a 45.degree. angle to the path of the incident light, deflects light passing from the input connection port into an output connection port. The actuator includes a plurality of piezoelectric bars mechanically coupled together in series in a meander line geometry such that the cumulative deflection of the piezoelectric bars is used to displace the mirror. The amount of displacement of the actuator is governed by a controllable voltage source, which applies a voltage across each of the piezoelectric bars. In one embodiment the microdynamical switch has a 1.times.

Abstract: A compact, liquid crystal-based acousto-optical control system for large (>1000 elements) phase-based phased array antennas includes a laser source providing polarized laser beams processed in an in-line interferometric optical architecture that uses two acousto-optic deflectors (AODs) driven by a microwave signal that preferably has a frequency of one-half the desired radar carrier frequency. The AODs and associated polarization rotators generate a plurality of optical signal pairs, each pair having one positive and one negative first order doppler shifted light beam, the positive and negative doppler shifted beams being orthogonally linearly polarized. A phase delay is introduced in a predetermined one of the light beams in each optical signal pair via electrical control of an array of birefringent-mode nematic liquid crystal cells in a spatial light modulator (SLM), while the non-phase delayed light beam in each pair serves as a reference for interferometric detection.

Abstract: A compact, stable, and optically efficient two dimensional spatial light modulator-based electro-optical control system for large (>1000 elements) phase-based phased array antennas uses an acousto-optic modulator (AOM) driven by a microwave signal at the desired radar carrier. A phase delay is introduced via electrical control of an array of birefringent-mode nematic liquid crystal cells that selectively phase delays a polarized signal light beam, while a non-phase delayed doppler shifted polarized beam is used as a reference for microwave signal generation via interferometric detection through a photodiode. The optical design provides a very fast (in nsecs) wideband carrier hopping capability. An alternative embodiment of the invention uses a deformable mirror device (DMD) SLM to introduce the required phase shifts.

Abstract: A phased array antenna system has optical architecture comprising free space delay units and associated spatial light modulators compatible for operation with temporally incoherent or coherent laser light to produce signals having selected time delays to actuate antenna elements of an antenna array to transmit electromagnetic radiation at a selected beam angle from the phase array. The same optical architecture is used to process electromagnetic signals detected by the antenna array to produce an output signal for display or processing which corresponds to the radiation detected at the selected beam angle.