Optoelectraulic devices based on interference induced carrier modulation
First Claim
1. A correlator based on interference induced carrier modulation, said correlator comprising:
- a sensor system comprising a sensor element operative to supply charge carriers when excited by an energy beam and means for generating a sensor signal in response to said charge carriers;
means for directing first and second beam signals at the sensor element to form an interference pattern thereon when the beam signals overlap in time and space on the sensor element, said interference pattern producing a spatial modulation in the distribution of said carriers, said first and second beam signals comprising respective interfering components which overlap in time, beam frequency and space at the sensor, and where the two interfering components have intensities that are within a factor of three of being identical; and
means for monitoring the sensor signal to detect a parameter of the sensor signal which varies as a function of the presence of the interference pattern.
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Accused Products
Abstract
A subpicosecond solid state optical correlator based on interference induced carrier modulation includes a photosensor circuit having a photoconductive element and a pair of opposed electrodes. A voltage difference is created across the electrodes to define an electrical field direction, and the element operates to generate charge carriers in response to optical energy incident on the photoconductive element. First and second optical signals are directed onto the photoconductive element to form an interference pattern thereon when the signals overlap in time and space. This interference pattern produces spatial modulation of the distribution of the carriers into lines or planes, at least some of which are not parallel to the electrical field direction. The resulting photocurrent is monitored to detect a parameter associated with the presence or absence of the interference pattern. The interference pattern defines a characteristic nodal spacing between adjacent ones of the lines, and the carriers include higher mobility carriers and lower mobility carriers. The ambipolar diffusion length is no greater than the characteristic nodal spacing, and an integrated value of the photocurrent is therefore less when the optical signals overlap in optical frequency and time and form the interference pattern than when the optical signals do not overlap in optical frequency and time.
19 Citations
55 Claims
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1. A correlator based on interference induced carrier modulation, said correlator comprising:
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a sensor system comprising a sensor element operative to supply charge carriers when excited by an energy beam and means for generating a sensor signal in response to said charge carriers; means for directing first and second beam signals at the sensor element to form an interference pattern thereon when the beam signals overlap in time and space on the sensor element, said interference pattern producing a spatial modulation in the distribution of said carriers, said first and second beam signals comprising respective interfering components which overlap in time, beam frequency and space at the sensor, and where the two interfering components have intensities that are within a factor of three of being identical; and means for monitoring the sensor signal to detect a parameter of the sensor signal which varies as a function of the presence of the interference pattern. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21)
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22. A subpicosecond solid state optical correlator based on interference induced carrier modulation, said correlator comprising:
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a photosensor circuit comprising a semiconductor photoconductive element, a pair of opposed electrodes, each on a respective side of the element, and means for generating a voltage difference across the electrodes to define an electrical field direction;
said element operating to generate charge carriers in response to optical energy incident on the photoconductive element, said charge carriers interacting with the voltage difference to create a photocurrent between the electrodes;means for directing first and second optical signals to photoconductive element, said first and second optical signals comprising respective interfering components which overlap in time, optical frequency and space at the photoconductive element, and where the two interfering components have intensities that are within a factor of three of being identical to form an interference pattern thereon, at least one of said interfering components being modulated, thereby time modulating said interference pattern, said interference pattern producing spatial modulation of the distribution of said carriers into planes, at least some of which are not parallel to the electrical field direction; and means for monitoring the photocurrent to detect a parameter associated with the time modulation of the interference pattern; said interference pattern a characteristic nodal spacing between adjacent ones of the lines, said carriers including higher mobility carriers and lower mobility carriers, and said carriers having a characteristic ambipolar diffusion length no greater than the characteristic nodal spacing such that an integrated value of the photocurrent is less when the interfering components form the interference pattern than when the interfering components do not. - View Dependent Claims (23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37)
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38. An optical demultiplexer for a multiplexed optical signal comprising components at optical frequencies ν
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1 and ν
2, said demultiplexer comprising;a photosensor having a photosensitive element operative to supply charge carriers in response to optical energy incident on the photosensitive element, and means for generating a sensor signal in response to said charge carriers, said photosensitive element positioned such that the multiplexed optical signal falls on the photosensitive element; means for directing a probe optical signal to the photosensitive element, said probe optical signal having an optical frequency distribution that overlaps with a first one of the components but not with the other of the components such that the probe signal forms an optical interference pattern with said first one of the components on the photosensitive element when the probe signal and the first one of the components overlap in time and space, said interference pattern producing a spatial modulation in the distribution of said carriers; and means for monitoring the sensor signal to detect a parameter of the sensor signal which varies as a function of the presence of the interference pattern, thereby demultiplexing the first and second components. - View Dependent Claims (39, 40, 41, 42, 43)
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1 and ν
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44. An optical correlator comprising:
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a photo sensor having a photosensitive element operative to supply charge carriers in response to optical energy incident on the photosensitive element, and means for generating a sensor signal in response to said charge carriers; means for directing first and second optical signals to the photosensitive element to form an interference pattern thereon when the first and second optical signals overlap in time and space, said interference pattern producing a spatial modulation in the distribution of said carriers; means for monitoring the sensor signal to detect a parameter of the sensor signal which varies as a function of the presence of the time modulated interference pattern; and delay means for delaying said second optical signal by a variable amount prior to incidence of the second optical signal on the photosensitive element, thereby allowing the second optical signal to be adjusted in phase with respect to the first optical signal. - View Dependent Claims (45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55)
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Specification