Nanometer-Resolution and Large-Dynamic-Range Optical Fiber Displacement Sensor Based on Single Pound-Drever-Hall Feedback Loop

• Published in: Journal of lightwave technology Vol. 43; no. 5; pp. 2386 - 2393
• Main Authors: Zhang, Yixiang, Xu, Zhilin, Wu, Junhui, Liang, Yurong, Sun, Qizhen, Zhou, Zebing
• Format: Journal Article
• Language: English
• Published: New York IEEE 01.03.2025; The Institute of Electrical and Electronics Engineers, Inc. (IEEE)
• Subjects: Aerospace engineering; Algorithms; Demodulation; Displacement measurement; Dynamic range; Fabry-Perot interferometers; Feedback loop; Feedback loops; fiber Fabry-Perot interferometer (FFPI); Fiber gratings; Field programmable gate arrays; Geophysics; High resolution; Laser mode locking; Measurement by laser beam; Optical fiber sensors; Optical fibers; pound-drever-hall (PDH) technique; Reflection; Resonance; Structural engineering; Wavelength measurement
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/JLT.2024.3486011

Displacement measurement with high resolution and large dynamic range is highly demanded in various fields. In this paper, a wide range nanometer displacement measurement system based on Fiber Fabry-Perot Interferometer (FFPI) and Pound-Drever-Hall (PDH) technique was proposed and experimentally demonstrated. Single PDH feedback loop based on incremental Proportion Integration Differentiation (PID) algorithm was constructed through field programmable gate array (FPGA) to read the resonant wavelength variation of the FFPI, which greatly simplifies the demodulation system. Due to the inherently narrow resonant bandwidth of FFPI and the single PDH feedback loop, the displacement measurement with high resolution and large dynamic range was realized. Displacement resolution of 8 nm, noise floor of 12 pm/Hz 1/2 at 10 Hz and dynamic range of 127 dB at 10 Hz were achieved experimentally. The proposed optical fiber displacement sensor based on single PDH feedback loop is simple yet robust, facilitating the practical applications in the fields of structural engineering, aerospace, geophysics, and nanotechnology.