Processing of multiple wavelength signals transmitted through free space
First Claim
1. A method for receiving high frequency signals, comprising:
- transmitting a coherent beam comprising at least one signal including first and second data modulated onto the beam from a laser transmitter through atmospheric turbulence to a receiver, wherein a diameter of the beam comprising said at least one signal is less than an inner scale of an atmosphere at an aperture of said transmitter, wherein a divergence angle of the beam is selected so that it exceeds a determined turbulence induced beam deviation so that a far-field footprint of the beam remains on the receiver aperture despite the atmospheric turbulence, wherein the receiver is located at a distance from the transmitter, wherein the at least one signal, after transmission through the atmospheric turbulence, has a distorted wave-front, wherein said transmitting of said first and second data is conducted at a rate greater than one gigabit/second, and wherein each of said first and second data is associated with first and second wavelength channels, respectively, the first wavelength channel being different from the second wavelength channel;
receiving said at least one distorted signal including said first and second data at a detector assembly associated with said receiver;
detecting said first data using a first detector unit of the detector assembly, wherein the first detector unit is located at a first position; and
detecting said second data using a second detector unit of the detector assembly, wherein the second detector unit is located at a second position that is different from said first position.
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Abstract
The present invention is directed to a laser communication receiver for wireless optical communication. A laser communication receiver includes a diffractive optical element to permit detectors at different spatial locations to detect different wavelengths of the optical signal. An immersion lens may be employed to focus the optical signal to a spot size smaller than the photoactive area of the detector. In one detector configuration, the optical signal is folded by a reflective surface and focused on a plurality of stacked detectors. The present invention further provides a method of manufacturing a detector and immersion lens assembly that provides a high degree of alignment between the lens and the corresponding detector.
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Citations
27 Claims
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1. A method for receiving high frequency signals, comprising:
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transmitting a coherent beam comprising at least one signal including first and second data modulated onto the beam from a laser transmitter through atmospheric turbulence to a receiver, wherein a diameter of the beam comprising said at least one signal is less than an inner scale of an atmosphere at an aperture of said transmitter, wherein a divergence angle of the beam is selected so that it exceeds a determined turbulence induced beam deviation so that a far-field footprint of the beam remains on the receiver aperture despite the atmospheric turbulence, wherein the receiver is located at a distance from the transmitter, wherein the at least one signal, after transmission through the atmospheric turbulence, has a distorted wave-front, wherein said transmitting of said first and second data is conducted at a rate greater than one gigabit/second, and wherein each of said first and second data is associated with first and second wavelength channels, respectively, the first wavelength channel being different from the second wavelength channel; receiving said at least one distorted signal including said first and second data at a detector assembly associated with said receiver; detecting said first data using a first detector unit of the detector assembly, wherein the first detector unit is located at a first position; and detecting said second data using a second detector unit of the detector assembly, wherein the second detector unit is located at a second position that is different from said first position. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14)
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15. A system for receiving high frequency signals, comprising:
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a receiver that receives at least one signal including first and second data and comprises a detector assembly; and a transmitter that transmits the at least one signal as a beam having a diameter that is less than an inner scale of an atmosphere at or near a transmitter aperture through atmospheric turbulence to the receiver, wherein the receiver is located at a distance of greater than 100 m from the transmitter, wherein the atmospheric turbulence is determined to be associated with a worst case atmospheric turbulence induced deviation of the beam, wherein a divergence angle of the beam is selected to exceed the atmospheric turbulence induced beam deviation for the beam under the determined worst case conditions, wherein the at least one signal, after transmission through the atmospheric turbulence, has a distorted wavefront, wherein said first and second data are each transmitted at a rate greater than one gigabit/second, wherein said first and second data are respectively associated with first and second wavelength channels, the first wavelength channel being different from the second wavelength channel, and wherein the detector assembly comprises at least a first detector unit located at a first position for detecting said first data, and a second detector unit located at a second position for detecting the second data, the second position being different from said first position. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22)
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23. A method for receiving high frequency data associated with at least a first wavelength channel, comprising:
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receiving at a first receiving location said first wavelength channel after the first wavelength channel has passed through atmospheric turbulence and thereby become optically distorted; finitely focusing said received first wavelength channel with a first optical element to form a focused first beam having a focused first spot size, wherein said first focused beam is focused at a first location; further finitely focusing the focused first beam with a second optical element at said first location to form a further focused first beam having a further focused first spot size that is smaller than the focused first spot size, wherein the first and second optical elements are at different spatial locations; detecting at least a portion of the data in the further focused first beam; receiving at said first receiving location a second wave length channel after the second wave length channel has passed through atmospheric turbulence and thereby become optically distorted, wherein said first and second wavelength channels are transmitted as part of a first beam; finitely focusing said received second wavelength channel with said first optical element to form a focused second beam having a focused second spot size, wherein said second focus beam is focused at a second location; further finitely focusing the focused second beam with a third optical element at said second location to form a further focused second beam having a further focused second spot size that is smaller than the focused second spot size, wherein the first and third optical elements are at different spacial locations; detecting at least a portion of the data in the further focused second beam. - View Dependent Claims (24, 25, 26, 27)
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Specification