Sub-Shot-Noise laser Doppler Anemometry with Amplitude-Squeezed Light

Abstract

Amplitude-squeezed light from a quantum-well semiconductor laser with weak optical feedback from a highly dispersive grating is employed for laser Doppler anemometry. Up to 2 dB noise reduction below the shot-noise level is observed with a feedback factor of $1.5\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$. Enhanced sensitivity is demonstrated in the Doppler measurement of a gas flow velocity with an improvement in the signal to noise ratio of 1.0 dB above the shot-noise limit.