Amplitude squeezing of light by means of a phase-sensitive fiber parametric amplifier

We experimentally demonstrate generation of bright sub-Poissonian light by means of parametric deamplification in a phase-sensitive fiber amplifier th at is based on a balanced nonlinear Sagnac interferometer. On direct detect ion, the photocurrent noise falls below the shot-noise limit by (0.6 +/- 0. 2) dB (1.4 dB when corrected for detection losses). To observe the noise re duction we employed a scheme that used two orthogonally polarized pulses to cancel the noise that arises from the predominantly polarized guided-acous tic-wave Brillouin scattering in the fiber. We also present a simplified se miclassical theory of quantum-noise suppression by this amplifier, which is found to be in good agreement with the experimental results. (C) 1999 Opti cal Society of America OCIS codes: 270.6570, 060.4370.