Long-Period Fibre Grating Thin Film Sensors Based on Cladding Mode Coupling
XU Yan-Ping, GU Zheng-Tian, CHEN Jia-Bi
1College of Optical and Electronic Information Engineering, University of Shanghai for Science and Technology, Shanghai 200093
2College of Science, University of Shanghai for Science and Technology, Shanghai 200093
Long-Period Fibre Grating Thin Film Sensors Based on Cladding Mode Coupling
XU Yan-Ping;GU Zheng-Tian;CHEN Jia-Bi
1College of Optical and Electronic Information Engineering, University of Shanghai for Science and Technology, Shanghai 200093
2College of Science, University of Shanghai for Science and Technology, Shanghai 200093
Abstract： Based on a method of rigorous vector-field analysis, a numerical model of triple-clad long-period fibre grating is established. The vector components of the electric field for the HE11 cladding mode are plotted to study the field distribution of the cladding mode. The local intensity curves of the first six l = 1 cladding modes are also given. It is found that the low-order HE modes have a larger proportion of intensity localized in the core than the low-order EH modes, just like the double-clad LPFG. Further, the coupling constant between the core mode and the cladding mode is analysed. The results show that the coupling constant of the low-order HE increases monotonously when the mode number becomes larger, and it varies monotonously with the film thickness except for a certain specific region.
2005, Vol. 22 
