可重构上下路复用器中平面波导光栅的FDTD法分析

Analysis of planar waveguide grating in reconfigurable optical add-drop multiplexer using FDTD method

建立了用于可重构上下路复用器(ROADM)中的平面波导光栅的基本模型,讨论了目前制备平面波导器件的主要材料及其特性.给出平面波导光栅二维时域有限差分(FDTD)法和完全匹配层(PML)边界条件的数值分析模型.对基于Ⅲ-Ⅴ族半导体材料的平面波导光栅进行了数值模拟,讨论分析了周期数、占空比和倾斜角变化对光栅谱特性的影响.随着光栅周期数的不断增多,其在反射波长处的透射率不断减小,谱线趋于平坦;增大占空比,反射波长向长波方向移动;增大倾斜角,将会在短波长处激励出新的模式.

The basic model of planar waveguide gratings in reconfigurable optical add-drop multiplexer （ROADM） is presented. The characterization of the materials used in planar lightwave circuit is discussed. Two dimensional planar waveguide gratings based on In-V materials are analyzed with finite-difference time-domain （FDTD） method and perfect matched layer （PML） boundary condition. The characterization of the gratings varied with the number of periods, duty and tilted angle are discussed respectively. Increasing the number of periods, the transmittivity is reduced and the reflective spectrum is flatter near the reflective wavelength. The reflective wavelength is shift to long wavelength when the duty is increased. Furthermore, new mode is excited in the shorter wavelength when the tilted angle is increased.