Generation of squeezed pulses with a Sagnac loop fiber interferometer using a non-soliton femtosecond laser pulse at 800 nm

We experimentally demonstrate generation of a squeezed vacuum at 800 nm with a Sagnac loop fiber interferometer. When negative dispersion is properly added to an input laser pulse to compensate for the fiber dispersion, the level of squeezing is improved. A squeezed vacuum of 0.45dB is obtained at a dispersion of -0.0157 ps²for the 1.5 m-long fiber loop. Since the squeezed vacuum is degraded by guided acoustic-wave Brillouin scattering (GAWBS), the noise level of the squeezing is improved by -0.3dB at a liquid nitrogen temperature. We also demonstrate generation of photon number squeezing at -1.3 dB.