Method and apparatus for coherent detection in optical processors
First Claim
1. An optical processor apparatus comprising:
- a light source for providing a coherent source beam,a spatial light modulator for modulating the source beam with an input information signal to produce a modulated beam, said modulated beam diverging into spacially separated frequency components including a zero frequency component from said source beam,reference beam generator means for forming a reference beam from said zero frequency component such that said reference beam appears to diverge from a reference point,an optical detector having an aperture positioned for receiving said reference bean and particular ones of said spatially separated frequency components whereby said particular ones of said spatially separated frequency components are coherently detected to produce an output information signal as a function of the input information signal.
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Abstract
A method of and an apparatus for coherently detecting modulated optical signals employing optical mask-generated signals is disclosed. A spatial light modulator modulates a source beam with an information signal composed of one or more frequency components within its frequency bandwidth. The frequency components which are output from the modulator, including the zero frequency component, diverge and become spatially separated. A reference beam is formed from the zero frequency component by a reference beam generator. The reference beam is generated so as to appear to diverge from a reference point located at or near the spatial light modulator. The optical detector performs coherent detection by squaring the sum of the frequency components and the reference beam to provide an output information signal as a function of the input information signal.
29 Citations
26 Claims
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1. An optical processor apparatus comprising:
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a light source for providing a coherent source beam, a spatial light modulator for modulating the source beam with an input information signal to produce a modulated beam, said modulated beam diverging into spacially separated frequency components including a zero frequency component from said source beam, reference beam generator means for forming a reference beam from said zero frequency component such that said reference beam appears to diverge from a reference point, an optical detector having an aperture positioned for receiving said reference bean and particular ones of said spatially separated frequency components whereby said particular ones of said spatially separated frequency components are coherently detected to produce an output information signal as a function of the input information signal. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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12. An optical processor apparatus comprising:
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a light source for providing a coherent source beam, a spatial light modulator for modulating the source beam with an input information signal to produce a modulated beam, said modulated beam diverging into spacially separated frequency components including a zero frequency component from said source beam, a transform lens for transforming said frequency components, including said zero frequency component, of said modulated beam, and an optical mask positioned to diffract said zero frequency component from said transform lens to form said reference beam, an optical detector having an aperture positioned for receiving said reference beam and particular ones of said spatially separated frequency components whereby said particular ones of said spatially separated frequency components are coherently detected to produce an output information signal as a function of the input information signal. - View Dependent Claims (13, 14, 15, 16, 17, 18, 19, 20, 21, 22)
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23. A method of optical processing comprising:
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providing a coherent source beam, modulating the source beam in a spatial light modulator with an input information signal to produce a modulated beam, said modulated beam diverging into spacially separated frequency components including a zero frequency component from said source beam, forming a reference beam from said zero frequency component such that said reference beam appears to diverge from a reference point, receiving said reference beam and particular ones of said spatially separated frequency components in the aperture of an optical detector to coherently detect said particular ones of said spatially separated frequency components and produce an output information signal as a function of the input information signal. - View Dependent Claims (24, 25, 26)
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Specification