  We experimentally investigate the evolution of the direct detection noise
figure of a non degenerate phase sensitive amplifier based on nonlinear fiber,
as a function of the relative phase between the signal, idler, and pump, all
other parameters remaining fixed. The use of a fiber with a high stimulated
Brillouin scattering threshold permits to investigate the full range of phase
sensitive gain and noise figure without pump dithering. Good agreement is found
with theory, both for signal only and combined signal and idler direct
detections.
