确定光子晶体光纤轴向方位角的侧视光强特征法

Determination of Azimuth Angle of Photonic Crystal Fiber by Characteristic Analysis of Side Transmission Images

光子晶体光纤轴向方位角的确定在光纤器件的加工制作中具有重要的意义.采用平行光侧向照射光子晶体光纤,研究了六边形结构、混合结构以及大模场结构这三种光子晶体光纤,获取其在不同轴向方位角时的侧视光强图像.随着光纤绕轴向旋转,其光强图像出现特定的亮纹光强特征,通过分析得到亮纹光强特征值随光纤轴向旋转之间的变化关系,发现其透射光强图像的光强特征值呈现周期性变化,并与光纤空气孔结构有一定对应关系.采用Tracepro仿真模拟三类光子晶体光纤的侧视光强图像特征,在模拟侧视光强图像中,也出现随轴向旋转变化而变化的亮纹特征,模拟侧视光强亮纹变化特征与实验亮纹特征具有相似的变化规律.对比光子晶体光纤亮纹光强特征值随轴向方位角变化关系的实验曲线与模拟曲线,发现当光源平行于光纤空气孔构成的近似六边形结构的顶角连线照射时,其亮纹光强特征值出现极大值,可以实现光子晶体在特定轴向方位角的定位.

Determination of azimuth angle of photonic crystal fiber is essential in the fabrication of devices based on photonic crystal fiber. The side images of hexagonal.hybrid and large mode area-20 structures of photonic crystal fibers were studied by illuminating the side of photonic crystal fibers vertically. The side images vary with the rotation of the fibers, and they display special light intensity characteristics. The characteristic values of images show periodic variation, which is corresponding with the inner structure of photonic crystal fibers. Simulation analysis for photonic crystal fibers were made by Tracepro software, the results of simulation show that the characteristic values of side images change with the rotation of fiber, and they perform the similar features with the experimental research. Compared with thecharacteristic curve of the experimental and the simulation results, the characteristic values has maxima values around the vertex direction of hexagonal structure formed by air holes, and it can be used to distinguish azimuth angle of photonie crystal fibers.