US 11,689,283 B1
Free-space optical communication system using a backchannel for power optimization
Stephen Philip Efthyvoulos, La Crescenta, CA (US); Eric Douglas Miller, Sherman Oaks, CA (US); Chien-Chung Chen, Thousand Oaks, CA (US); and Slaven Moro, San Diego, CA (US)
Assigned to Meta Platforms, Inc., Menlo Park, CA (US)
Filed by Meta Platforms, Inc., Menlo Park, CA (US)
Filed on Mar. 26, 2021, as Appl. No. 17/213,712.
Claims priority of provisional application 63/002,261, filed on Mar. 30, 2020.
Int. Cl. H04B 10/112 (2013.01); H04B 10/118 (2013.01); H04B 10/564 (2013.01); H04W 16/28 (2009.01); H04B 10/50 (2013.01); H04W 84/06 (2009.01)
CPC H04B 10/1123 (2013.01) [H04B 10/118 (2013.01); H04B 10/5057 (2013.01); H04B 10/564 (2013.01); H04W 16/28 (2013.01); H04W 84/06 (2013.01)] 15 Claims
OG exemplary drawing
 
1. A device comprising:
an optical modulator configured to generate an optical beam, wherein the optical beam encodes network data and has a beam intensity, a beam direction and a carrier frequency;
an optical power amplifier configured to adjust a transmitted power of the optical beam;
a transmit beam angle mechanism, configured to:
adjust the beam direction; and
transmit the optical beam to a remote receiver over a free-space optical link; and
a controller, configured to:
receive backchannel data from the remote receiver comprising a received power, a bit error rate, and a carrier frequency offset between local oscillator frequencies used by the device and the remote receiver; and
modify a plurality of characteristics of the optical beam based on the backchannel data, the plurality of characteristics comprising:
adjustment of the beam intensity to maintain the bit error rate at a level that is correctable by the remote receiver while not further increasing the beam intensity; and
adjustment of the carrier frequency to reduce the carrier frequency offset,
wherein the carrier frequency offset is a difference between a local oscillator frequency of the device and a second local oscillator frequency of the remote receiver and is minimized to reduce the transmitted power of the optical beam for the bit error rate.