Probability density functions for intensity induced phase noise in CW phase demodulation systems

This paper discusses two probability density functions related to continuous wave (CW) phase demodulation systems such as those used in optical sensing. In the first case, we show that if the input intensity noise in the quadrature streams of the demodulator is Gaussian, then the induced phase noise is approximately Gaussian. If, however, the noise in both in-phase and quadrature streams is correlated, then the intensity induced phase noise exhibits a periodic dependence on the input phase and follows new asymmetric density distributions. We give expressions for the mean and variance for both processes.