Photon-Number Squeezed Solitons from an Asymmetric Fiber-Optic Sagnac Interferometer

Abstract

Direct photon-number squeezing is demonstrated, for the first time to our knowledge, in a nonlinear fiber-optic interferometer. Launching 126-fs solitons into a highly asymmetric Sagnac loop, the maximum photocurrent noise reduction was $3.9\pm 0.2\mathrm{dB}$ below shot noise, corresponding to $6.0\pm 0.9\mathrm{dB}$, when corrected for linear losses. The loop is a model system for squeezing generated by the interference of two pulses after nonlinear propagation through a fiber.