Compact wide tunable bandwidth phased array antenna controller
First Claim
1. An optical signal control system comprising:
- a source of coherent, polarized light;
acousto-optic means for generating a reference beam cluster and a signal beam cluster from light beams emanating from the light source, each of said clusters comprising a plurality of light beams;
one of said beam clusters being diffracted and one of said beams clusters being undiffracted;
an optical phase modulating device coupled to said acousto-optic means and disposed to selectively delay the phase selected light beams in said signal beam cluster;
means for combining along collinear paths said reference light beams said signal light beams passing from said modulating device; and
heterodyne means for detecting interference between respective ones of the combined signal light beams and corresponding reference light beams.
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Accused Products
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.
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Citations
38 Claims
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1. An optical signal control system comprising:
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a source of coherent, polarized light; acousto-optic means for generating a reference beam cluster and a signal beam cluster from light beams emanating from the light source, each of said clusters comprising a plurality of light beams;
one of said beam clusters being diffracted and one of said beams clusters being undiffracted;an optical phase modulating device coupled to said acousto-optic means and disposed to selectively delay the phase selected light beams in said signal beam cluster; means for combining along collinear paths said reference light beams said signal light beams passing from said modulating device; and heterodyne means for detecting interference between respective ones of the combined signal light beams and corresponding reference light beams. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15)
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16. A phased array antenna system comprising:
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a laser assembly adapted to generate beams of coherent, linearly polarized light; an optical signal processing system optically coupled to said laser assembly, said signal processing system being adapted to produce a plurality of reference light beams and a plurality of differentially phase shifted signal light beams in a manner such that said signal light beams and said reference light beams will pass from said system along collinear and coincident paths, said optical signal processing system comprising; an acousto-optic modulator (AOM) being disposed so that incident light beams will be Bragg matched to said AOM and so that light beams that pass therethrough will split into a diffracted beam cluster and an undiffracted beam cluster, a predetermined one of said beam clusters comprising a reference beam cluster and one of said beam clusters comprising a signal beam cluster, said AOM being adapted to be driven by a microwave source having a selected drive frequency; and an optical phase modulating device coupled to said AOM so that the predetermined signal light beams will pass therethrough, said optical phase modulating device comprising a plurality of pixels so that respective ones of said signal light beams will pass throug a respective corresponding pixel, each of said pixels being individually controllable to selectively change the phase of the signal light beam passing therethrough; a transceiver module coupled to said optical signal processing system comprising a heterodyne detection array of photodiodes, each of said photodiodes being disposed to receive corresponding ones of said reference and signal light beams so as to convert said light beams into electrical beamforming signals, said corresponding reference and light beam signals being collinear and coincident; and an antenna array electrically coupled to said transceiver module, said array comprising a plurality of antenna elements and being operable in a transmit or receive mode, each of said antenna elements being driven by a respective one of said electrical beamforming signals, said electrical beamforming signals collectively controlling the transmit and receive electromagnetic patterns of said antenna array. - View Dependent Claims (17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30)
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31. A method of processing optical signals to control a phased array antenna having a plurality of antenna elements, comprising the steps of:
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passing a plurality of coherent, linearly polarized light beams through an acousto-optic modulator (AOM) to split said beams into a reference beam cluster and a spatially separate signal beam cluster such that one of said beam clusters emerging from said AOM is undiffracted and the other one of said beam clusters is diffracted; shifting the phase of selected ones of the signal light beams with respect to the reference light beams; detecting interference between relative phases of respective ones of said signal light beams and said reference light beams and generating an electrical beamforming signal corresponding to the detected interference for each of said signal light beams and a corresponding reference beam; and controlling the transmit and receive electromagnetic radiation patterns of said phased array antenna with said electrical beamforming signals. - View Dependent Claims (32, 33, 34, 35, 36, 37, 38)
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Specification