一種基于強度調制的新型光纖溫度傳感器

介紹了一種基于光強調制的新型光纖溫度傳感器,它是通過光刻腐蝕和鍍敷金屬材料的
方法在光纖上直接形成的。對其測溫原理進行了研究:刻紋光纖受軸向應變時,其中傳輸的光信號輸出功率對軸向應變相當敏感,很容易測量出光信號輸出功率減少,原因是由于刻紋段光纖受軸向應變時纖芯折射率及半徑變化的結果,且刻紋段與未刻紋段將發(fā)生大小不同的應變。當外界環(huán)境溫度發(fā)生變化時,由敷在刻紋光纖外表面上的金屬敷層將隨環(huán)境溫度的變化而熱脹冷縮,這樣使光纖同時產生一個沿光纖軸方向的拉伸應變。從而導致光纖中輸出光功率發(fā)生改變。實驗結果表明:該光纖溫度傳感器的性能是由其結構參數、金屬敷層材料種類及其對稱性所決定,具有較好的重復性和較高的溫度響應靈敏度。
關鍵詞:光纖;溫度傳感器;靈敏度
Abstract :A novel optical fiber temperature sensor with metal coating is presented. The geometry of the features is de2 fined 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 opera2 tion 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 tempera2 ture change is repeatable. The sensor has higher temperature response sensitivity.
Key Words :Optical Fiber ; Temperature Sensor ;Sensitivity