Generation of 1.5 µm Squeezed Vacuum Pulse Using a Sagnac Loop Interferometer

Abstract

Photon-number squeezing and quadrature squeezing were studied using ultrafast fibre nonlinear optics pumped by 1.5 µm femtosecond laser pulses. To obtain quadrature squeezing using an Erbium doped fibre amplifiers (EDFA) light source, we developed temporal homodyne technology to exclude the excess noise of an EDFA light source. We also performed a quadrature squeezing experiment using an optical parametric oscillator light source in stead of an EDFA light source exhibiting substantially high excess noise. Although the photon-number squeezing of -3dB was obtained from an asymmetric Sagnac fibre loop, the quadrature noise could not decrease to less than the Shot noise level without cooling the fibre, which is presumably due to GAWBS. To suppress guided acoustic wave Brillouin scattering, we refrigerated the fibre loop by liquid nitrogen, and squeezing at -0.7 dB was obtained by cooling the fiber at liquid nitrogen temperature.