一种基于强度调制的新型光纤温度传感器

Novel Optical Fiber Temperature Sensor Based on Light Intensity Modulation

介绍了一种基于光强调制的新型光纤温度传感器 ,它是通过光刻腐蚀和镀敷金属材料的方法在光纤上直接形成的。对其测温原理进行了研究 :刻纹光纤受轴向应变时 ,其中传输的光信号输出功率对轴向应变相当敏感 ,很容易测量出光信号输出功率减少 ,原因是由于刻纹段光纤受轴向应变时纤芯折射率及半径变化的结果 ,且刻纹段与未刻纹段将发生大小不同的应变。当外界环境温度发生变化时 ,由敷在刻纹光纤外表面上的金属敷层将随环境温度的变化而热胀冷缩 ,这样使光纤同时产生一个沿光纤轴方向的拉伸应变。从而导致光纤中输出光功率发生改变。实验结果表明 :该光纤温度传感器的性能是由其结构参数、金属敷层材料种类及其对称性所决定 ,具有较好的重复性和较高的温度响应灵敏度。

A novel optical fiber temperature sensor with metal coating is presented.The geometry of the features is defined photolithographically and the structures are built directly onto the fiber cladding by chemical etching.The working principle of this sensor is analyzed in detail.When an etched fiber is stretched,the etched section has a smaller cross section and therefore a larger strain.And the changes of its radius,index and mode volume are larger than those in an unetched section.There is a power loss in joining two fibers with different mode volumes.This is the principle underlying the operation of the temperature sensors with symmetric etched structures.When the temperature of outside is increase or decrease,the outcome is a tendency for the metal coating to expand or to contract,and the fiber is strained.The result is the output power through the fiber will decrease or increase.By monitoring the change of power transmitted through the etched fiber,the change of the temperature is inferred.The results of experiment show that the characteristics of this sensor depend on the structure parameters of etched fiber sections,the type and the symmetry of metal coating.The response under temperature change is repeatable.The sensor has higher temperature response sensitivity.