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设计和制作了一种基于单模多模细芯单模光纤马赫曾德尔(Mach-Zehnder)干涉仪结构,可同时测量折射率和温度的传感器。该传感器中,多模光纤和细芯单模熔接点充当光耦合器。导入光纤中传输的光经多模光纤后在细芯光纤的纤芯和包层中激发出纤芯模和包层模,不同模式光在细芯光纤中传输时将产生光程差,再经细芯单模熔接点耦合成为导出光纤的纤芯模而干涉。传感器透射光谱随着环境折射率和温度的变化发生漂移,通过监测不同级次的干涉谷可实现折射率和温度的同时测量。通过对传感器的透射光谱进行傅里叶变换分析可知该透射光谱主要由LP01模和LP16模干涉形成。该传感器透射光谱中1535nm附近干涉谷的折射率和温度响应灵敏度的理论值分别为-55.90nm/RIU和0.0501nm/℃(其中RIU为折射率单位);1545nm附近干涉谷的折射率和温度响应灵敏度的理论值分别为-56.26nm/RIU和0.0505nm/℃。在折射率和温度的变化范围分别为1.3449~1.3972和20℃~90℃的环境中对传感器的响应特性进行实验研究,结果表明:透射光谱中1535nm附近干涉谷的折射率和温度响应灵敏度分别为-53.03nm/RIU和0.0465nm/℃;1545nm附近干涉谷的折射率和温度响应灵敏度分别为-54.24nm/RIU和0.0542nm/℃。理论分析与实验结果相一致。该传感器在生物医学领域有较好的应用前景。
A sensor based on Mach-Zehnder interferometer with single-mode multi-mode single-mode core and single-mode fiber is designed and fabricated to measure the refractive index and temperature simultaneously. In this sensor, multi-mode fiber and fine-core single-mode splices act as optical couplers. Light into the optical fiber after transmission through the multimode fiber core and cladding in the core of the fiber core and cladding mode excited, different modes of light in the core optical fiber transmission will produce optical path difference, and then by The fine-core single-mode splice points couple to interfere with the core mode of the outgoing fiber. The transmission spectrum of the sensor drifts with the change of the refractive index and the temperature of the environment. Simultaneous measurement of the refractive index and the temperature can be achieved by monitoring the interfering valleys at different levels. Through the Fourier transform analysis of the sensor’s transmission spectrum, the transmission spectrum is mainly formed by LP01 mode and LP16 mode interference. The theoretical values of the refractive index and the temperature response sensitivity of the sensor in the vicinity of 1535 nm in the transmission spectrum are -55.90 nm / RIU and 0.0501 nm / ° C, respectively (where RIU is the refractive index unit); the refractive index and temperature response of the interference valley near 1545 nm The theoretical values of sensitivity are -56.26 nm / RIU and 0.0505 nm / ° C, respectively. The experimental results show that the refractive index and the temperature response sensitivity of the interferometer valley near 1535 nm in the transmission spectrum are respectively: (1) the refractive index and the temperature response sensitivity of the sensor in the range of 1.3449 ~ 1.3972 and 20 ℃ ~ 90 ℃, respectively -53.03 nm / RIU and 0.0465 nm / ° C; the refractive index and temperature response sensitivity of the interfering trough near 1545 nm were -54.24 nm / RIU and 0.0542 nm / ° C, respectively. The theoretical analysis is consistent with the experimental results. The sensor has good application prospect in the field of biomedicine.