In-line frequency-nondegenerate phase-sensitive fiber-optical parametric amplifier

We demonstrate a phase-sensitive fiber-optical parametric amplifier based on frequency-nondegenerate four-wave mixing in the telecom band. An input signal is phase-sensitively amplified and the measured gain response complies well with the theory. Efficient phase-sensitive amplification can be achieved even after transmitting an optical double-sideband signal over 25 km of single-mode fiber.