Polarized-holographic filtering providing improved extinction ratio
First Claim
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1. A communication system comprising:
- a source of energy to propagate a signal along a communication path;
a detector positioned in the communication path; and
a filter having a surface with a polarizing film disposed thereon and first and second holographic optical elements each of which has a holographic transform function disposed throughout the volume of the filter, the filter being disposed in the path to filter the signal in accordance with properties of the holographic transform function and the polarizing film to remove portions of the signal having unwanted characteristics, defining a transformed signal to impinge upon the detector, with the transform function associated with said first holographic optical element matching the transform function associated with said second holographic element.
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Abstract
A filtering technique for free space communication that features an improved extinction ratio by providing a filter that employs a bulk holographic transform function and a polarizing film. In this manner, a greater number of channels of communication may be provided in a unit volume while preventing unwanted cross-talk between the communication channels. To that end, the system includes a source of energy to direct energy along a path, a detector disposed in the path, and a filter. The filter has a surface upon which a polarizing film is disposed and a holographic transform function recorded throughout a volume thereon.
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Citations
20 Claims
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1. A communication system comprising:
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a source of energy to propagate a signal along a communication path;
a detector positioned in the communication path; and
a filter having a surface with a polarizing film disposed thereon and first and second holographic optical elements each of which has a holographic transform function disposed throughout the volume of the filter, the filter being disposed in the path to filter the signal in accordance with properties of the holographic transform function and the polarizing film to remove portions of the signal having unwanted characteristics, defining a transformed signal to impinge upon the detector, with the transform function associated with said first holographic optical element matching the transform function associated with said second holographic element. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A communication system comprising:
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a source of optical energy to propagate a signal along an optical path;
an optical detector positioned in the communication path; and
an optical filter having a surface with a polarizing film disposed thereon and first and second holographic optical elements each of which has a holographic transform function disposed throughout the volume of the optical filter, the optical filter being disposed in the optical path to filter the signal in accordance with properties of the holographic transform function and the polarizing film to remove portions of the signal having unwanted characteristics, defining a transformed signal to impinge upon the detector, with the transform function associated with said first holographic optical element matching the transform function associated with said second holographic element. - View Dependent Claims (16, 17)
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18. A communication system comprising:
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an array of optical transmitters to generate optical energy to propagate along a plurality of axes;
an array of optical receivers, each of which is positioned to sense optical energy propagating along one of the plurality of optical axes;
a first array of refractory lenses, each of which is disposed in one of the plurality of axes and has a first polarizing film disposed thereon and a first holographic transform function recorded throughout a volume thereof to filter from the optical energy unwanted characteristics, with the first polarizing film and first holographic transform function associated with a subgroup of the lens of the first array, defining a transfer function, differing from first polarizing film and the first holographic transform function associated with the remaining lenses of the first array of lenses; and
a second array of refractory lenses, each of which is disposed between the first array of lenses and the array of optical receivers to collect optical energy propagating along the one of the plurality of optical axes, with a subset of the lenses of the second array having a second polarizing film thereon and a second holographic transform function recorded in a second volume thereof, with the second polarizing film and the second holographic transform function matching the transfer function. - View Dependent Claims (19, 20)
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Specification