通过改变微波电光调制器的调制频率,实现光频率扫描。利用光频移产生的后向瑞利散射光干涉图样的变化,可得到传感温度变化信息。基于温度变化前后两次扫描频率曲线的互相关特性及其与温度变化量的对应关系,提出了光频率扫描扩展方案。理论分析和实验结果表明,该方案可有效提高系统的温度测量检测范围。实验中,信噪比提升了2.13 dB,系统可检测的最小温度变化量约为0.029 ℃。

By changing the modulation frequency of the microwave electro-optic modulator, we achieve the optical frequency scanning. Using the variation of the interference pattern of the backward Rayleigh scattered light generated by the optical frequency shift, we can obtain the information of the sensing temperature change. Based on the cross-correlation properties of the two scanning frequency curves before and after the temperature change and their correspondence with the temperature variation, we propose an optical frequency scanning extension scheme. Theoretical analysis and experimental results show that the proposed scheme can effectively improve the temperature detection range of the system. In the experiment, the signal-to-noise ratio is improved by 2.13 dB, and the minimum detectable temperature change of the system is about 0.029 ℃.