Correlations and Excess Noise in One-port and Balanced Two-port Homodyne Detection

Abstract

Abstract The fluctuations in the processes of one-port and balanced two-port homodyning are calculated in the operator picture for a weak signal and a strong local oscillator beam where the last is contaminated with Gaussian excess noise. For such a mixture of coherent and chaotic light, we construct a physical model with the help of a linear laser amplifier. To be able to measure phase-dependent quantum fluctuations like squeezing with one-port homodyning, demands a Poisson-like photon distribution of the local oscillator and stringent requirements on its intensity. The Poisson-like photon distribution can also be achieved by a very low reflectivity which is equivalent to strong attenuation. These conditions are relaxed for balanced two-port homodyning but certain less stringent consequences of the excess noise are derived to occur.