单轴各向异性晶体纤芯偏振光传播特性分析

Analysis of Propagation Properties of Polarized Wave in Uniaxial Anisotropic Crystal Fiber Core

提出了一种光纤芯为单轴各向异性晶体、光轴方向为x轴、包层为各向同性材料的新型光纤模型。应用波导方程近似地求出光纤内场强分布,利用数值模拟分析了o光和e光的传播常数β随归一化频率V变化的色散曲线。进一步分析了光纤芯半径对o光和e光的色散方程的影响,结果表明光纤芯半径对o光和e光截止频率没有影响。基于以上特性,分别讨论了o光和e光传播常数β随光纤芯半径变化的曲线。通过分析光纤介电常数对色散曲线的影响,表明当入射光的归一化频率在一定范围内时,通过改变x方向和y方向介电常数的比值可以改变光纤内传播光的偏振方向。研究结果为设计偏振光纤提供了理论依据。

A novel fiber model with isotropic crystal cladding, uniaxial anisotropic crystal fiber core that optical axis is parallel to the x-axis is proposed. The field intensity distribution is approximately obtained by waveguide equation. Using the transmission matrix method and numerical simulation method, the dispersion curves that the propagation constants flof o ray and e ray change with normalized frequency V are analyzed. By deeply analyzing the influence made by cores of optical fibers on dispersion curves, it is shown that the radii of optical fiber cores donr t exert influence on cutoff frequency. Based on the above results, the curves that the propagation constants fl of o ray and e ray change with optical fiber core are achieved respectively. By analyzing the influence of the dielectric constants on dispersion curves, it is indicated that the polarized direction of light in the fiber can be changed by the ratio of x directional dielectric constant and y directional dielectric constant in the certain range of normalized frequency propagating in the fiber. This work provides a theoretical foundation for designing the polarization fiber.