Spatially dephasing local oscillator for coherent free-space optical communications

A method of providing a coherent transceiver system, the method comprising:

• providing a local oscillator (LO) light source to generate an LO optical signal;
• coupling an adaptive fiber array to the LO light source;
• configuring the adaptive fiber array to dephase the LO optical signal and to generate a dephased LO signal;
• coupling a balanced detector to the adaptive fiber array, the balanced detector comprising a beam splitter and optical couplers;
• configuring the balanced detector to generate a heterodyne signal comprising a plurality of channel heterodyne signals using the dephased LO signal and an optical input signal;
• configuring the beam splitter and the optical couplers to generate a first and a second combined beam to be out of phase by 180 degrees, wherein the heterodyne signal comprises a difference between the first and the second combined beam;
• and
• providing a controller to receive the heterodyne signal and to generate one or more control signals,
• wherein the adaptive fiber array is configured to utilizes the one or more control signal to dephase the LO optical signal.

A free-space optical (FSO) communication system comprising:

• at least two FSO transceivers:
• an FSO transceiver of the at least two FSO transceivers coupled via an FSO modem to a network, wherein the FSO transceiver comprises:
• a local oscillator (LO) light source configured to generate an LO optical signal;
• an adaptive fiber array coupled to the LO light source and configured to dephase the LO optical signal;
• a balanced detector coupled to the adaptive fiber array and configured to receive a dephased LO signal from the adaptive fiber array and an optical input signal and to generate a heterodyne signal comprising a plurality of channel heterodyne signals, wherein the balanced detector comprises a beam splitter and optical couplers configured to generate a first and a second combined beam to be out of phase by 180 degrees, and the heterodyne signal comprises a difference between the first and the second combined beam;
• and
• a controller configured to receive the heterodyne signal and to generate one or more control signals,
• wherein the adaptive fiber array utilizes the one or more control signal to dephase the LO optical signal.