光子晶体光纤液体传感器过渡区光场传输特性

Characteristics of the transition-layer of photonic crystal fibers used in liquid sensors

采用有限元方法,通过数值模拟来研究用于液体光纤传感器的全反射型光子晶体光纤中的光传输特性.针对灌输液体后,光子晶体光纤过渡区呈现的双层环形结构进行分析,在所提出理论计算模型的基础上,给出了不同结构下的模场分布,讨论各参量对模场面积和能量分布的影响.研究结果表明,灌输液体后,光场要经历一个扩散后再集中的过程;在浸润凹液面处,模场面积和能量分布是随着凹面处内环半径的递增而逐渐集中的,而非浸润凸液面处模场面积则集中的更快;光纤中的光传输特性也受灌输液体的性质影响.这些都为光子晶体光纤液体传感器的设计提供了理论参考依据.

In this paper the light transmission characteristics of total reflection photonic crystal fiber （PCF） were investigated using the finite element method, which is very important and useful for liquid fiber sensing. The double-deck annular structure was analyzed in photonic crystal fibers injected with liquid. In order to provide a theoretical model, mode field distributions of PCF with different structures were calculated, and the influences of parameters on mode area and energy distribution were also examined. The results suggested that after PCF was injected with liquid, the light field of the mode spreaded first, then centralized towards the core. In the case of concave liquid surfaces, the mode area and energy distribution centralized gradually with increasing inner - ring radius. However, in the case of convex liquid surfaces, the mode area concentrated faster and the light transmission characteristics in PCF were also influenced by the liquid.