基于液晶填充的带隙型光子晶体光纤的滤波特性

Filter Properties of Band Gap Photonic Crystal Fibers Based on Liquid Crystal Filling

在实芯光子晶体光纤的周期排列的空气孔包层中,填充高折射率液晶介质,使其形成光子带隙。由于填充后低折射率的纤芯周围分布着高折射率液晶棒,光子晶体光纤的横向因布拉格反射而形成了许多传输带,呈现多通道滤波特性。基于光子带隙理论,利用平面波展开法对填充液晶前后光子晶体光纤传导机制的转变进行了探讨,研究了填充液晶对光子晶体光纤滤波性能的影响。结果表明,当电场增大时,滤波通道中心向长波方向移动,滤波通道带宽增大;而对于相同的外加电场,随着液晶折射率的逐渐增大,滤波特性与电场增大情况类似,光子带隙开始向长波方向漂移,同时带隙的宽度也逐渐变大。

The photonic band gap is proposed by filling high-index liquid crystal into its periodically arranged air holes of the clad of solid core photonic crystal fibers （PCFs）. Owing to the high-index liquid crystal clubs arranged around the low-index core after filling, PCFs show conductive bands and multi-channel filtering properties induced by transversely Bragg reflectance. Based on photonic band gap theory and plane wave expansion method, the effect of liquid crystal on the conduction change of PCF and filtering properties are researched. The results show that with the increase of electric filed, the filter channel center moves to long wavelength, and the bandwidth of filter channel increases. However, for the same applied electric field, with the increase of refractive index, the photonic band gap moves to long wave length and meanwhile the band gap increases.