镀有SiO_2-WO_3薄膜LPFG折射率传感特性研究

采用四层阶跃折射率几何模型,研究了镀有SiO2-WO3薄膜LPFG在溶液折射率测量方面的特性,并与未镀膜情况进行了比较。当LPFG包层外镀膜后,测量纯水、CaCl2溶液(浓度为450gL-1,折射率为1.4056)时波长漂移量分别是未镀膜时的1.67和2.55倍;谐振峰的损耗变化分别是未镀膜时的4.44和2.82倍;在1.36-1.38折射率范围内,传感器的灵敏度和分辨率分别是216.58nm和0.82×10-5,是镀膜前的3.27和0.30倍,说明镀膜后LPFG对溶液折射率测量的灵敏度和分辨率得到了很大的提高。

Research for the Refractive Index Sensor Characteristic of the LPFG Coated SiO2-WO3 Film

Using a four-layer-step refractive index geometric model,the refractive index characteristic of the LPFG coated SiO2-WO3 film was researched in solution.These results were compared with uncoated film.The experiment results were that when the LPFG cladding was coated,the resonant wavelength shift of the LPFG in water and CaCl2 solution(concentration 450gL-1,index 1.4056) were about 1.67 times and 2.55 times respectively comparing to those uncoated;the resonant peak loss changes were also 4.44 times and 2.82 times respectively.In 1.36-1.38 refractive index range,the sensor's sensitivity and resolution were 216.58nm and 0.82×10-5,which were 3.27 times and 0.30 times respectively comparing to those uncoated.It indicated that the sensitivity and resolution had been greatly improved when the LPFG coated film was used to measure the solution refractive index.