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US 12,015,440 B2Granted
Chip-scale receiver and method for free space optical coherent communications
AssigneeOAM Photonics LLC
InventorsKam Wai Clifford Chan, Chung Ki Wong
Life of this patent
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Abstract
The present disclosure relates to a chips-scale free-space optical (FSO) receiver with a wide two-dimensional field-of-view (FOV) that affords high data rate optical communication and rapid pointing and tracking (PAT) operations in an integrated design, and a method for FSO communication with PAT that supports high-speed node acquisition and network entry, and simple angle of arrival calculations.
Claims20
A receiver for free-space optical communication configured to operate between coherent and direct detection modes, comprising:
- a local oscillator light source configured to generate a local oscillator signal;
- an optical routing network coupling to said local oscillator light source;
- a receiver pixel array coupling to said optical routing network, wherein said receiver pixel array comprises a plurality of receiver pixels, each of said receiver pixels comprises:
- a free-space-to-waveguide optical antenna;
- an optical coupler with one of its input ports coupling to said free-space-to-waveguide optical antenna;
- at least two photodetectors coupling to output ports of said optical coupler;
- and
- a pixel electronic circuit configured to receive and process electrical outputs from said photodetectors;
- and
- a signal readout electronic circuit configured to switch said pixel electronic circuits in receiver pixels of said receiver pixel array between coherent detection mode and direct detection mode, and to receive electrical readout signals from said pixel electronic circuits;
- wherein, in operation, said receiver pixel array is configured to select one or more receiver pixels to receive an optical signal from free space through one or more free-space-to-waveguide optical antennas of said selected receiver pixels;
- wherein when said receiver is configured to operate in the coherent detection mode, said optical routing network is configured to route said local oscillator signal from said local oscillator light source to said selected receiver pixels of said receiver pixel array;
- said selected receiver pixels are configured to couple said local oscillator signal into the pixels;
- optical couplers of said selected receiver pixel mix said local oscillator signal and said received optical signal;
- said optical couplers split said mixed local oscillator and received optical signals;
- said split signals are detected by photodetectors coupling to said optical couplers in said selected receiver pixels;
- pixel electronic circuits of said selected receiver pixels are switched to operate in the coherent detection mode by said signal readout electronic circuit to receive and process electrical outputs from said photodetectors;
- and said pixel electronic circuits output electrical readout signals to said signal readout electronic circuit;
- and
- wherein when said receiver is configured to operate in the direct detection mode, said selected receiver pixels are configured to decouple from said local oscillator signal;
- optical couplers of said selected receiver pixels split said received optical signal without mixing with said local oscillator signal due to the absence of said local oscillator signal in said selected receiver pixels;
- said split received optical signals are detected by photodetectors coupling to said optical couplers in said selected receiver pixels;
- pixel electronic circuits of said selected receiver pixels are switched to operate in the direct detection mode by said signal readout electronic circuit to receive and process electrical outputs from said photodetectors;
- and said pixel electronic circuits output electrical readout signals to said signal readout electronic circuit.
21 more elements
A method for free-space optical communication switchable between coherent detection mode and direct detection mode, comprising:
- generating a local oscillator signal from a local oscillator light source;
- selecting a plurality of receiver pixels from a receiver pixel array;
- receiving an optical signal from free space by at least one receiver pixel in said selected plurality of receiver pixels;
- in the coherent detection mode, performing the steps of
- routing said local oscillator signal to said selected plurality of receiver pixels through an optical routing network;
- coupling said local oscillator signal into said selected plurality of receiver pixels;
- mixing said local oscillator signal and said optical signal in said selected receiver pixel that receives said optical signal;
- splitting said mixed local oscillator and optical signals;
- detecting said split signals by photodetectors;
- switching a pixel electronic circuit of said selected receiver pixel to coherent detection mode;
- processing electrical outputs from said photodetectors by said pixel electronic circuit to produce an electrical readout signal;
- and
- outputting said electrical readout signal to a signal readout electronic circuit;
- and
- in the direct detection mode, performing the steps of
- decoupling said local oscillator signal from said selected plurality of receiver pixels;
- splitting said optical signal without mixing with said local oscillator signal due to the absence of said local oscillator signal in said selected receiver pixel that receives said optical signal;
- detecting said split optical signals by photodetectors;
- switching a pixel electronic circuit of said selected receiver pixel to direct detection mode;
- processing electrical outputs from said photodetectors by said pixel electronic circuit to produce an electrical readout signal;
- and
- outputting said electrical readout signal to a signal readout electronic circuit.
19 more elements
Dependencies are inferred from the claim text.