侧边抛磨光子晶体光纤传输特性理论分析

Theoretical Analysis of Optical Propagation Characteristics of Side-Polished Photonic Crystal Fiber

在建立了侧边抛磨光子晶体光纤D型光纤光学模型的基础上,采用三维有限差分光束传输法计算和分析了侧边抛磨光子晶体光纤的光功率衰减、传输模场等与抛磨区几何参数(剩余半径、轴向旋转角、侧边抛磨区长度)的变化关系。结果表明,当剩余半径大于-1.5μm时,侧边抛磨光子晶体光纤的光功率衰减随着剩余半径的减小而增大;光沿着光纤传输时,基模光传输到抛磨区光功率发生衰减,经过抛磨区后,基模光功率出现回升。沿不同的轴向旋转角方向侧边抛磨,剩余半径大于0.5μm时,侧边抛磨光子晶体光纤的光功率衰减随着剩余半径变化的差别较小;剩余半径足够小时,光沿着光纤传输到抛磨区时,会产生高阶模,沿轴向旋转角θ=30°侧边抛磨时基模模场分布分散程度最大,且在抛磨区产生更多的高阶模。剩余半径大于1.5μm时,抛磨光纤长度变化对输出光功率影响很小,剩余半径小于1.5μm时,输出光功率透射率随着光纤抛磨长度的变化呈振荡变化。分析结果可为侧边抛磨光子晶体光纤的器件制作提供理论指导。

Based on the optical model of D type of side-polished photonic crystal fiber （SPPCF）, both the attenuation of optical power and the field distribution of propagation modes in the device of SPPCF are calculated and analyzed with the variation of geometry factors, such as residual radius after side polishing, axial rotation angle, and the length of side-polished area, by using three-dimensional finite difference beam propagation method （FDBPM）. The analysis results show that when the residual radius is longer than --1.5μm, the shorter the residual radius is, the larger the attenuation of the optical power in SPPCF is; the optical power of LP01 mode of the SPPCF is attenuated in the side-polished area, and recovered after light passes through the side-polished area. When the residual radius is longer than 0. 5μm, there is a small difference between the attenuations of optical power of PCFs polished atdifferent axial rotation angles. When the residual radius is small enough, high order modes appear during the process of the light passing through the side-polished area. The mode field distribution is the most dispersive one and many high order modes appear in side polished area when the axial rotation angle is 30°. When the residual radius is longer than 1.5 μm, the change of the side-polished length has a little impact on the attenuation of optical power in SPPCF; when the residual radius is shorter than 1.5 μm, the attenuation of optical power changes in oscillation as the side- polished lenRth varies. The analvsis mav provide a theoretic guide to device fabrication of SPPCF.