中文摘要：

基于Mach.Zehnder干涉仪原理，结合光纤熔锥技术，设计并制作了一种结构为细锥.多模.细锥的液体折射率传感器。光经第一个多模细锥节点时，将在后面的多模光纤的纤芯和包层中激发出纤芯模和包层模，不同的模式有不同的模式折射率；再经中间多模光纤部分传输时，不同模式光之间将产生光程差；最后在第二个多模细锥节点处耦合而干涉。对该传感器输出干涉光谱中干涉谷波长随外界溶液折射率变化的规律进行了理论分析和实验研究。实验结果表明，溶液折射率变化范围为1.379~1.402时，干涉谱中1 566.68 nm附近的干涉谷波长与溶液折射率有单调递增的变化关系，对应的灵敏度为783 nm/RIU。该传感器制作简单、结构紧凑、成本低、灵敏度高，在生物医学领域有较好的应用前景。

英文摘要：

On the basis of the principle of Mach?Zehnder interferometer(MZI)and fiber pyrometric cone technology,a liq?uid refractive index sensor with thin?taper?multimode?thin?taper structure was designed and produced. When the light transmitsthrough the first multimode thin taper node,the fiber core mode and cladding mode are excited in the subsequent multimode fi?ber core and cladding. Since different modes have their own refractive indexes,the optical path difference is produced among dif?ferent light modes when the light transmits through the intermediate multimode fiber,and then,it forms the coupling and inter?ference at the second multimode thin taper node. The change rule of the interference wave length(in interference spectrum out?put by the sensor)with the outside solution reflective index is analyzed theoretically and studied in experiment. The experimen?tal results indicate that,when the variation range of solution reflective index is 1.379～1.402,the interference wave length near?by 1 566.88 nm in interference spectrum is monotone increasing with the solution reflective index,and the corresponding sensi?tivity is 783 nm/RIU. The sensor has the advantages of simple manufacturing,compact structure,low cost and high sensitivity,and has better application prospect in biomedical domain.