Detection of amplitude modulation with squeezed light for sensitivity beyond the shot-noise limit
An improvement in precision beyond the limit set by the vacuum-state or zero-point fluctuations of the electromagnetic field is reported for the detection of amplitude modulation encoded on a weak signal beam. The improvement is achieved by employing the squeezed light from an optical parametric oscillator to reduce the level of fluctuations below the shot-noise limit. An increase in signal-to-noise ratio of 2.5 dB relative to the shot-noise limit is demonstrated.
© Copyright 1988 Optical Society of America Received January 22, 1988; accepted March 21, 1988 We gratefully acknowledge the contributions of J. L. Hall. This research was supported by the U.S. Office of Naval Research and by the Venture Research Unit of British Petroleum America.