High-Resolution Optical Fiber Strain Sensor Array Based on Pound-Drever-Hall Technique with Fast Phase Regulation Method

Sensors that use Pound-Drever-Hall (PDH) technology benefit from the good performance and high resolution but are in shortage of large-scale multiplexing. This paper proposed a fast phase regulation method for the hybrid PDH multiplexing scheme based on space division multiplexing and time division multiplexing. Using both the information provided by an I/Q demodulator, the points from the error signal that the close-loop control requires can be rebuilt in the software with a phase rotation algorithm within a time period of less than 20 us. The relationship between the multiplexing scale and parameters selection is also given in this paper, showing that the system can have a larger multiplexing scale up to several tens sensors with appropriate parameters selection. A multi-channel strain array of up to 10 channels with a resolution better than 10 pϵ/√Hz@1 Hz over 50 Hz band per channel has been realized in this paper, and the system works with good channel crosstalk isolation. The experiment results show that the developed instrument has potential usage in the field of large-scale quasi-static strain measurement and earthquake observation.