Li Zhihong, Shen Jie, Ji Qiuping, Ruan Xiukai, Zhang Yaoju, Dai Yuxing, Cai Zhennao
J Opt Soc Am A Opt Image Sci Vis. 2018 Mar 1;35(3):397-405. doi: 10.1364/JOSAA.35.000397.
This work presents a sensitive refractive index sensor based on the dual resonance of an excessively tilted long period fiber grating (Ex-TLPFG). The Ex-TLPFG is tuned to couple the guided core mode with only the polarization-degenerate cladding mode LP, which consists of TE/TM and HE vector modes. It is found that the p-polarized LP1,lp mode exhibits a higher sensitivity than that of the s-polarized LP1,ls mode. An optimized sensitivity as high as 12182.9 nm/RIU is achieved for the p-polarized LP1,2p mode at the low refractive index region by tuning the initial resonance condition. The sensing performance is also evaluated through the power measurement method for a single resonance band. It is demonstrated that the improved sensitivity in this work for diameter-reduced Ex-TLPFG is much higher than that for the conventional LPFG based devices, which makes this sensing platform very attractive for a variety of index sensing applications.
这项工作提出了一种基于过度倾斜长周期光纤光栅（Ex-TLPFG）双共振的灵敏折射率传感器。Ex-TLPFG被调谐以仅将导模芯模与由TE/TM和HE矢量模组成的偏振简并包层模LP耦合。研究发现，p偏振的LP1,lp模比s偏振的LP1,ls模具有更高的灵敏度。通过调整初始共振条件，在低折射率区域，p偏振的LP1,2p模实现了高达12182.9 nm/RIU的优化灵敏度。还通过单共振带的功率测量方法评估了传感性能。结果表明，这项工作中直径减小的Ex-TLPFG的灵敏度提高远高于基于传统LPFG的器件，这使得该传感平台对各种折射率传感应用非常有吸引力。
