DBR光纤激光器压力传感系统的研制

研制了一种基于正交偏振形式的双频分布式布拉格反射(Distributed Bragg Reflection, DBR)光纤激光器光纤压力传感器系统。当外部压力作用在光纤激光器谐振腔上时,光纤晶体双折射的变化会引起正交偏振方向上的激光频率发生变化,从而导致输出拍频频率改变。利用快速光电二极管将双频激光输出的拍频信号转换成射频电信号,通过一个射频混频电路将该信号与频率合成器产生的本地振荡信号混频并低通滤波放大整形,变为400 M以下的调频信号,再利用ECL定时计数电路系统记录拍频信息并通过USB接口送入计算机。实验表明,在0～1.5 N范围内线性拟合度高达99.97 %,压力灵敏度为400 MHz·N^-1。

Development of DBR Fiber - laser Pressure Sensor System

An orthogonal dual - polarization distributed - Bragg - reflector （DBR） fiber - laser sensor system for pressure measurement is presented. The birefringence will be changed by ex- tern pressure load applied on fiber laser cavity, and the orthogonal laser frequency will also be changed, thus the beat frequency of the two lasers varied. A high speed photodiode is used to convert the polarization beating frequency optical signal of the DBR fiber laser to radio - fre- quency （RF） electric signal. Through a radio - frequency mixer circuit and a low pass filter, the RF signal is mixed with a local RF signal generated by a frequency synthesizer, then output signal is a frequency modulation signal with carrier frequency below 400 M, and is amplified and shaped to ECL level pulse signal. Then, with an ECL timing and counter system, the frequency variation of beating signal with vibration information is collected by a computer via USB inter- face. Experiment results show that linearity is up to 99.97 % in the pressure load range of 0 to 1.5 N and pressure sensitivity is 400 MHz ·N-1.