Output-Noise Statistical Characterization for Digital-Phase-Demodulation Systems With Intensity-Based Input Noise

A large fraction of fiber-optic-sensor systems make use of interferometry in the measurement process, implying the need for demodulation to obtain the encoded signal of interest. Of great interest for sensor characterization is the performance of the demodulation scheme under the influence of noise. In this paper, we construct a very general transfer function that relates intensity-induced input noise to its phase noise realization in the output for a wide class of digital-demodulation techniques. We proceed to compute analytically a probability density function of this output noise and use this to compute low-order statistical moments of the output noise. We compare the analytical formulations with simulated data from a representative demodulation scheme used in a currently existing fiber Bragg grating (FBG) sensor system and find excellent agreement