湿腐蚀法制备U形塑料光纤折射率传感器

为提升折射率测量灵敏度、方便测量,通过湿腐蚀法制备了高灵敏度的U形塑料光纤折射率传感器.从理论上分析了多模塑料光纤宏弯曲折射率传感器的原理,利用射线法对塑料光纤中传输光场进行近似,获得多模塑料光纤宏弯曲模式损耗的表达式.采用丙酮和甲醇混合溶液作为腐蚀剂,利用湿腐蚀法对塑料光纤进行处理,观察不同腐蚀剂浓度腐蚀后光纤表面形貌,得到最佳腐蚀剂浓度为丙酮浓度80％.采用热定型法对腐蚀后的光纤进行宏弯曲处理,通过改变光纤芯径及弯曲半径优化传感器性能.利用655 nm红光激光器作为光源对其灵敏度进行测试,在1.30 ～1.45的较大折射率范围内,得到最佳灵敏度为618％/RIU(RIU为折射率单位).实验结果证明,通过宏弯曲处理可以使传感器灵敏度得到提升,并且U形探头使测量更加方便,可以广泛应用于折射率传感领域.

U-Shaped Plastic Optical Fiber Refractive Index Sensor Prepared by Wet Etching Technique

In order to improve the sensitivity of liquid refractive index measurement and make the measurement process more convenient, U-shaped POF(Plastic Optical Fiber) probes for RI(Refractive Index) sensing with high sensitivity is prepared by wet etching. The principle of the multi-mode POF macro-bending RI sensor is analyzed. The light field transmitted in the POF is approximated by the ray method, and the expression of mode loss caused by macro-bending in the multi-mode POF is obtained. The cladding and part of the core are removed through a mixed solution of acetone and methanol. The surface morphology of the optical fiber after corrosion with different etchant concentrations is observed, and the best etchant concentration is 80% with acetone. The corroded optical fiber is produced to macro-bending structure by thermal setting method, and the sensor performance is optimized by changing the fiber core diameter and bending radius. The sensitivity of 618% / RIU is obtained in the large index range of 1. 30 to 1. 45 at wavelength of 655 nm. It is proved that the sensitivity of the sensor can be improved through the macro-bending processing, and the U-shaped probes make the measurement more convenient, which can be widely used in refractive index sensing.