A noise propagation model for a 3×3 optical demodulation scheme

This work presents a model of an exact transfer function and its associated probability structure for intensity noise propagation through an operationally-passive fiber optic demodulation scheme used with fiber Bragg grating sensor systems. This new model is generalized to any input noise probability structure and includes the possibility of full or partial correlation among the demodulation input channels. For the specific case of Gaussian-distributed intensity noise, this work shows that the demodulators nonlinear transfer function induces phase-dependent output bias output variance attenuation or amplification. Experimental data are provided to validate the model.