混合型导光的全固态光子晶体光纤的特性分析

Analysis on the Properties of All-Solid Photonic Crystal Fiber with Micro-Structured Core

通过在全固态光子带隙光纤的纤芯中心处掺入高折射率锗,形成具有微结构芯的混合型导光的全固态光子晶体光纤。采用全矢量有限元法,对光纤的导光机制、模场、损耗、色散等特性进行了数值分析。结果表明,中心高折射率棒的半径从0开始增大,小于包层高折射率棒的半径时,基模有效折射率由靠近带隙下边界处开始向上移动,导光机制由带隙效应导光向混合型导光转变,损耗随之降低。在短波处,全内反射效应占主导,带隙边缘对损耗的影响减小,损耗曲线逐渐表现出随波长单调递增的特性。长波处,导光机制以带隙效应为主,损耗曲线整体下移。通过改变中心棒的大小,可以灵活调节光纤的零色散波长。研究结果表明,当中心棒的半径为0.5μm时,零色散波长向短波方向移动30nm;半径为1.2μm时,零色散波长向长波方向移动230nm,调整带宽达到260nm。

All-solid hybrid photonic crystal fiber with micro-structured core is proposed. The micro-structured core is consisted of pure silica and a high refractive index germanium-doped rod. Using the full-vector finite-element method, the fiber＇s guiding mechanism, mode field, confinement loss and dispersion are investigated. Simulation results demonstrate that with the increment of central high refractive index rod＇s diameter from 0μm to less than cladding high-index rod, the fundamental model＇s effective index moves up from closing to the bandgapr s lower boundary. Furthermore, the guiding mechanism is transformed from bandgap effect into hybrid mechanism and the confinement loss is reduced. In the short wavelength, the guiding mechanism is dominated by the totally international reflection mechanism, the bandgap edge＇s influence on loss reduces and the loss decreases monotonically with the decrement of wavelength. But in the long wavelength, light is guided by the bandgap effect and the loss curve moves down integrally. By adjusting the radius of the central high refractive index rod, zero dispersion wavelength of the fiber can be tailored flexibly. When the radius of the central rod is set to 0.5μm, the zero dispersion wavelength shifts to shorter wavelength, about 30 nm away from the original value. When the radius is 1.2μm, the zero dispersion wavelength can be shifted to longer wavelength, about 230 nm away. The tunable band-width is up to 260 nm.