Abstract: An ultralow noise PSA (e.g., <3 dB) is described that utilizes a pair of local, high power pump sources to impart gain to a relatively weak received communication signal using a four-wave mixing (FWM) process within a nonlinear optical component. A feedback loop positioned around the nonlinear optical component is used to generate the pump beams, with a portion of the amplified output supplied as an error signal to a phase locking control circuit within the feedback loop. The phase locking control circuit monitors any phase changes in the received communication signal and adjusts the phase(s) of the pump beams to maintain phase locking (synchronizing the pumps to the communication signal) to achieve high output gain from the PSA.

Abstract: A free-space optical communication link is proposed that utilizes phase-sensitive amplification of the received optical signal at the input to the receiver portion of the link. The transmitter component of the FSO link generates an idler signal that is transmitted through free space with the original data signal and used at the PSA in conjunction with a pump wave to impart gain onto the received information signal. The PSA performs four-wave mixing (FWM) of the data, idler and pump to create the amplified data signal. In one embodiment, the pump wave used to generate the idler at the transmitter is sent through free space with the information and idler signals and used by the PSA to perform amplification. Alternatively, the PSA may use a co-located pump laser, in combination with the received idler signal, to perform the phase-sensitive amplification process.

Abstract: A free-space optical communication link is proposed that utilizes phase-sensitive amplification of the received optical signal at the input to the receiver portion of the link. The transmitter component of the FSO link generates an idler signal that is transmitted through free space with the original data signal and used at the PSA in conjunction with a pump wave to impart gain onto the received information signal. The PSA performs four-wave mixing (FWM) of the data, idler and pump to create the amplified data signal. In one embodiment, the pump wave used to generate the idler at the transmitter is sent through free space with the information and idler signals and used by the PSA to perform amplification. Alternatively, the PSA may use a co-located pump laser, in combination with the received idler signal, to perform the phase-sensitive amplification process.