High resolution and accuracy model fitting interrogation method for optical fiber Polarization interferometric sensor

Abstract

Interrogation methods largely determine the performance of the entire sensing system. However, interrogation methods alone are unlikely to provide very good results. An accurate model for the optical fiber polarization interferometric sensor (PIS) has been meticulously formulated within the frequency domain, incorporating the mode birefringence dispersion term of polarization maintaining fibers (PMFs). A novel model-fitting interrogation approach for the PIS is initially proposed and validated through experimental demonstration, which is bifurcated into parameter initialisation and model fitting interrogation process during the operation of the PIS. Subsequently, the parameters are determined at varying temperatures using this method. The interrogation capabilities of the proposed method are then experimentally contrasted with the valley wavelength tracking method. Results corroborate that the measurement range of model-fitting approach is no longer restricted by the spectrum bandwidth. The resolution and accuracy of our approach are 89% and 8 times higher than the valley wavelength tracking method, respectively.