基于耦合边界的紧凑型光子晶体定向耦合器的优化设计

本文采用平面波展开法分析了双线型缺陷并列平行光子晶体波导的带隙结构、缺陷模式及耦合长度,提出了一种具有耦合边界的光子晶体定向耦合器,并探讨了光波在其中的传输性能.同时基于平面波展开法及时域有限差分法,深入分析和讨论了光波在光子晶体并列波导、光子晶体直角转弯模块中的工作模式和传输特性.利用该光子晶体定向耦合器结合光子晶体转角器件可以将两根平行标准单模光纤传输模式组合成交叉态、直通态和功分态等状态.仿真结果表明在交叉态和直通态时,使用该光子晶体定向耦合器的传输峰值可以在较大频率带宽内达到90%以上.

Optimum Design on Compact Photonic Crystal Waveguide Directional Coupler Based on Adiabatic Coupling

We present an optimal design of Photonic Crystal Waveguide Directional Coupler (PCW-DC) with adiabatic coupling boundary in this paper.The Planar Wave Expand method (PWE) is employed to analyze the band gap and the proprieties of defect mode in parallel PCW.A 90° bend PCW is designed to couple the PCW-DC and two parallel single mode fibers which connect to PCW-DC at port one and port two,respectively.The transmission proprieties of the PCW-DC with adiabatic coupling boundary are analyzed with finite-difference time-domain (FDTD) method.It is shown that use this PCW-DC can achieve efficient transmission ratio in cross state,bar state and power division state at different coupling length.The simulation results show that the coupling ratio can be higher than 90% in a wide wavelength range when the PCW-DC is designed in bar and cross states.