Order Jump Correction Method Based on Dispersion Deviation Compensation for Polarization Low-Coherence Interferometry

Polarization low-coherence interferometry (PLCI) is a promising technology for the demodulation of sensing signals. However, in such a system, the dispersion-induced fringe phase deviation will bring serious distortion to the demodulated results. In response to this challenge, a method is proposed to correct the fringe order jumps by exploiting the dispersion compensation equation. The distribution model of the actual optical path difference (OPD), corresponding to the ideal thickness of the birefringent optical wedge (BOW) in the system, is established. Combining the actual OPD distribution due to the birefringence and the interference fringes with double refraction dispersion variation, we can obtain the relationship between the deviation phase and the envelope peak (EP) of the interference fringes and can fully eliminate the fringe order jump error. A pressure experiment is carried out to verify the effectiveness of the proposed method. Compared with the conventional monochromatic frequency-domain absolute phase (MFDAP) algorithm, the proposed method can fundamentally suppress the fringe order jump problem induced by the dispersion without the loss of the demodulation accuracy and thus provides a new way for the precise demodulation of low-coherence interference fringes in large-range measurements.