Orthogonal Phase Demodulation of Optical Fiber Fabry-Perot Interferometer Based on Birefringent Crystals and Polarization Technology

Abstract

In this paper, we propose and demonstrate the optical fiber Fabry-Perot (F-P) interferometer based on birefringent crystals and polarization technology. For recovering the variation signals, the orthogonal signals are obtained based on the birefringent crystal characteristics and the proposal thickness difference between the two crystals. The differential cross multiplication (DCM) algorithm is utilized to demodulate the orthogonal signals to obtain the phase variation of the optical fiber F-P sensor. The proposed interferometer has a minimum detection phase of 0.014 rad/ √ Hz at the frequency of 25 kHz. In the experiment, two kinds of vibration signals with frequencies of 25 kHz and 15 kHz are used and the proposed interferometer SNR is 70 dB and 75 dB under the corresponding reference environment respectively. The experiment results show that the proposed interferometer can realize the measurement of large dynamic signals and has high stability. The proposed interferometer has the advantages of fast demodulation and good environmental adaptability.

Fast interrogation of dynamic low‐finesse Fabry‐Perot interferometers: A review

“…As shown in Figure 1(A)~(D), passive quadrature phase retrieval can be achieved by multiple wavelength, 19,20,34,38–40 and also by dual F‐P cavity, 35,41 birefringence crystal, 36,42 and 2*2 coupler 37 . Passive quadrature phase demodulation schemes have high stability.…”

Optical Interferometric MEMS Accelerometers

“…In addition, the method of generating two quadrature signals includes the double-cavity length method (Figure 28a), [115] the dualwavelength method (Figure 28b), [116] and the birefringent crystal method (Figure 28c). [117] The way to generate quadrature signals with double cavity length is to construct two interferometric cavities with a constant phase difference. The dual-wavelength method uses two lasers of different wavelengths to generate quadrature signals.…”

Environment-Robust Polarization-Based Phase-Shift Dynamic Demodulation Method for Optical Fiber Acoustic Sensor

“…The normalization coefficients are recorded to normalize when the optical power coefficient is 0.2, 0.4, 0.6 and 0.8. By using the traditional DCM [24] demodulation algorithm, which expression can be expressed as:…”

“…Besides constructing phase step from the wavelength change, the phase step can also be realized from the optical path differences (OPD) change. In our previous research, we proposed orthogonal phase shift as well as four-step phase shift with birefringent crystals [24], [25]. Lacking the compensation consideration on real-time optical power attenuation prevents its application in dynamic extreme environment such as Mars-like planet exploration task.…”