Study of Ellipse Fitting Phase Demodulation Technique With Reference Interferometer to Suppress the Impact of Laser Phase Noise

An ellipse-fitting cross-multiplication phase demodulation technique (EFCM-PDT) based on a reference interferometer is proposed to suppress the effect of laser-introduced phase noise (LPN). The sensor signal and the reference signal are processed by ellipse-fitting algorithm to obtain two pairs of orthogonal signals. In order to reduce the cost of computing power, the cross-multiplication (CM) algorithm is used to subtract the phase information of the interference signals to suppress the influence of LPN. The experimental results show that the suppression effect of EFCM-PDT on LPN was up to 41 dB and that the system has a noise floor of −126.35 dB at 160 Hz. Additionally, the system's operation time of 12-13 seconds is significantly shorter than that of the ellipse-fitting phase demodulation technique (EF-PDT), which can take up to 153 seconds. EFCM-PDT is an effective LPN suppression scheme while overcoming the slow operation of the EF-PDT system for the application of interferometric sensor technology.