液晶光子晶体光纤电场传感的模式特性

Mode Characteristics of Liquid Crystal Filled Photonic Crystal Fiber in Electric Field Sensing

光子晶体光纤（PCF）的导光特性可通过改变空气孔的结构参数（孔径、问距和排列方式）、材料填充等方法进行调节。由于自身具有电可调性，液晶作为PCF的填充材料具有很大的研究价值，可以用于制作电可调PCF。利用有限元法分析了液晶（E7）填充的光子晶体光纤的基模有效折射率、有效模场面积等参量随占空比、外电场的变化关系，得到了不同占空比下基模的截止电压和一定电压下基模的截止波长。结果表明光子晶体光纤的电压可调范围随占空比增大而增大；占空比一定时，电压越大，波长可调范围越小。这种液晶填充的光子晶体光纤可以应用于电场传感等领域。

Optical guiding characteristics of photonic crystal fibers （PCF） can be tuned by varying the parameters of air holes （diameter, distance and arrangement） and filling dielectric materials. Liquid crystal is one promising material used as the filling agent in PCF due to its electrical tunability, which can lead to the electrically tunable PCFs. Finite element method （FEM） is used to explore the effective refractive indices and effective areas of fundamental modes of PCF filled with liquid crystal （ET） as functions of duty cycles and voltages. Both the cut off voltages under variable duty cycles and cut off wavelengths under constant voltages are obtained for fundamental modes. Numerical results also show that cut off voltages increase as the duty cycles increasing, meanwhile the tunable wavelength range decreases as voltages increasing under constant duty cycles. PCFs filled with liquid crystal are expected in the application of electric field sensing.