US 12,413,307 B2
Chip-scale receiver and method for free space optical coherent communications
Kam Wai Clifford Chan, Albuquerque, NM (US); and Chung Ki Wong, Albuquerque, NM (US)
Assigned to OAM Photonics LLC, Albuquerque, NM (US)
Filed by OAM Photonics LLC, Albuquerque, NM (US)
Filed on May 15, 2024, as Appl. No. 18/665,113.
Application 18/665,113 is a continuation of application No. 18/048,779, filed on Oct. 21, 2022, granted, now 12,015,440.
Claims priority of provisional application 63/271,116, filed on Oct. 22, 2021.
Prior Publication US 2024/0305372 A1, Sep. 12, 2024
This patent is subject to a terminal disclaimer.
Int. Cl. H04B 10/112 (2013.01); H04B 10/61 (2013.01)
CPC H04B 10/112 (2013.01) [H04B 10/61 (2013.01)] 20 Claims
OG exemplary drawing
 
1. 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 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; optical couplers of said selected receiver pixels mix said local oscillator signal and said received optical signal to produce mixed signals; said optical couplers split said mixed signals to produce split signals; said split signals are detected by first photodetectors coupling to said optical couplers in said selected receiver pixels; pixel electronic circuits of said selected receiver pixels receive and process electrical outputs from said first photodetectors to produce first electrical readout signals; and said pixel electronic circuits output said first 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 second photodetectors coupling to said optical couplers in said selected receiver pixels; pixel electronic circuits of said selected receiver pixels receive and process electrical outputs from said second photodetectors to produce second electrical readout signals; and said pixel electronic circuits output said second electrical readout signals to said signal readout electronic circuit.