基于光纤腔衰荡光谱的浓度和温度测量

Measurement of concentration and temperature based on fiber loop ring-down spectroscopy

为了提高浓度和温度测量的灵敏度和稳定性,采用时域分析法监测光纤系统中的光损耗,研制了基于光纤环形腔衰荡光谱的传感系统。基于该系统对浓度和温度进行传感测量实验,分析了错位传感结构的参量选择,并研究了空载时腔内信号放大对脉冲强度和脉冲数量的影响。结果表明,当干涉长度L和错位量D分别为4cm和3.75μm时,干涉效果最优;脉冲强度是无腔内放大时的4倍且脉冲数量更多;当蔗糖和葡萄糖溶液浓度为0.100g/mL^0.400g/m L时,浓度灵敏度为756.51μs/(g/mL)和909.07μs/(g/mL),检测限为0.0014g/mL;当温度为30℃~200℃时,温度灵敏度为1.83μs/℃。该系统的设计和研究为浓度和温度的传感应用提供了有价值的指导。

In order to improve the sensitivity and stability of concentration and temperature measurement,the optical loss in the optical fiber system was monitored by means of time-domain analysis. A sensing system based on fiber loop ring-down spectroscopy（ FLRDS） was proposed. Based on the measurement results of concentration and temperature,parameter selection of the core-offset sensing structure was analyzed experimentally. The effect of intra-cavity signal amplification on pulse intensity and pulse number was studied. The results show that,when the interference length L and offset D are 4 cm and 3. 75μm respectively,interference effect is optimal. Pulse peak intensity is 4 times that without intra-cavity amplification and pulse number is bigger.When the sucrose and glucose concentration is 0. 100 g/mL ~ 0. 400 g/mL,concentration sensitivities are 756. 51μs/（ g/mL） and909. 07μs/（ g/mL）,and the detection limit is 0. 0014 g/mL. The temperature sensitivity is 1. 83μs/℃ in the range of 30℃ -200℃. The design and research of this system provide valuable guidance for sensing application of concentration and temperature.