Free space optical communication system and method

A method comprising:

• combine, via a first wavelength division multiplexer, a data signal and a pump signal;
• generate, based on the combined data signal and the pump signal and via a parametric amplifier, an idler signal that is a phase conjugate of the data signal;
• output, via second wavelength division multiplexer and based on an output of the parametric amplifier, the data signal and the idler signal to a first output channel and the pump signal to a second output channel;
• attenuate, via a pump attenuator coupled to the second output channel, the pump signal;
• combine, via a third wavelength division multiplexer, the data signal, idler signal, and attenuated pump signal into a combined signal;
• and
• transmit, via free space, the combined signal.

A device comprising:

• a wavelength division demultiplexer configured to receive a communication signal received from free space and output a first signal and a second signal that is a phase conjugate of the first signal at a first output of the wavelength division demultiplexer, and configured to output a pump signal at a second output of the wavelength division demultiplexer, based upon the communication signal received over free space from a satellite;
• a wavelength division multiplexer operatively coupled at a first input, to the wavelength division demultiplexer, and operatively coupled at a second input, to an output of a frequency stabilizer, the frequency stabilizer being operatively coupled to the wavelength division demultiplexer;
• an optical processor coupled to the output of the wavelength division demultiplexer;
• a variable delay element coupled to the optical processor and to the first input of the wavelength division multiplexer, wherein the optical processor and the variable delay element are configured to pass the first signal and the second signal upon being output by the wavelength division demultiplexer, and are configured to synchronize path lengths of the first signal and the second signal with the pump signal;
• a phase sensitive amplifier coupled to the wavelength division multiplexer;
• a feedback loop coupled to the wavelength division multiplexer in parallel with the phase sensitive amplifier and configured to phase-lock the pump signal with the first signal and the second signal;
• and
• a demodulator coupled to an output of the phase sensitive amplifier and configured to recover data in the received communication signal from one or more of the first signal or the second signal.