基于单模-多模-单模光纤模间干涉的传感系统

基于单模-多模-单模光纤（SMS）结构的模间干涉现象，在外界环境变化时SMS 光纤结构输出光场散斑图样的变化规律，提出了一种用于振动、应力及温度检测的光纤传感系统。该系统使用光电二极管测量散斑图样部分固定区域的光功率变化，即可得到施加在多模光纤上的外界应力，通过FFT 和Hilbert 变换，可得到外界振动（频率、幅度）和温度变化信息。对该系统的振动测量和温度测量进行定标后，经实验研究测得，该系统振动测量误差小于0.7 Hz，温度测量误差小于5.0%。该系统结构简单，成本低，并可用于多参量的测量。

Optical fiber sensing system based on multimode interference of single-mode-multimode-single-mode fiber structure

In this article, we proposed an optical fiber sensing system for measuring vibration, strain and temperature based on the multimode interference of single-mode-multimode-single-mode (SMS) fiber structure, because the output optical power of the SMS fiber structure changed with the external environment parameters, such as vibration (frequency and amplitude), strain and temperature. From the variation of the output optical power, the strain on the multimode fiber could be obtained. The frequency and amplitude of the vibration and temperature of the SMS fiber structure could be obtained when FFT or Hilbert transformation was employed. With the calibration of the system, some cases of vibration and temperature change were measured with the error of less than 0.7 Hz and 5.0%, respectively. The SMS optical fiber sensing system can be used for multi-parameter measurements with extremely simple structure and low cost.