Dynamic Demodulation of Low-Finesse Fabry-Perot Sensors Based on Instantaneous Frequency Analysis

• DOI: 10.1109/jlt.2022.3147596
• Publication Date: 2022-02-01T20:40:00Z
• Authors: Yuru Chen; Xiaohua Lei; Peng Zhang; Xianming Liu; Wei Zhang; Bin Shao; Hao Liu
• Keywords: Frequency deviation; Finesse; Spectrogram; Instantaneous phase

The optical path length (OPL) of the Fabry-Perot cavity may change during spectrum acquisition; it introduces demodulationerror or even causes demodulation failure based on traditional algorithms. To address this problem, relationship between dynamic OPL and instantaneous frequency is investigated. Demodulation analysis proposed. By combining spectrogram (SP) Wigner-Ville Distribution (WVD), an effective time-frequency (TF) method investigated to calculate at each sampling point in a period sweeping laser. Experimental results show that speed 4.8 MHz 2 KHz rate, max deviation sinusoidal variation around 0.14 μm, triangular 0.13 μm.