Abstract

In recent years, several experiments have established the optical parametric oscillator (OPO) as a practical source of highly correlated twin beams. These beams have an intensity difference noise substantially below the associated shot noise, for noise frequencies within the OPO cavity bandwidth. They present the additional feature of being laserlike and intense, making them convenient for experimental applications. Refinements on our OPO characteristics and photodiode efficiencies have yielded a reduction of the noise power in the intensity difference of 86% below the shot noise level.¹ A first use of twin beams is the production of a single light beam having an intensity squeezed noise. This can be achieved by monitoring the intensity of one beam with a photodiode and using this information to control the intensity fluctuations of the second beam with an electrooptic modulator.² Other applications to high sensitivity spectroscopic measurements such as linear and nonlinear absorption or dispersion can now be considered for practical use.

© 1991 Optical Society of America