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利用二维光子晶体的自准直和定向耦合效应设计了一种由一个自准直区域、耦合区和两个周期性介质波导组成分束器,利用平面波展开法从理论上研究了耦合区的色散关系,计算得到了耦合长度,同时使用时域有限差分方法模拟了电磁波在其中的传输特性,得到了稳态的电场分布,讨论了光波从自准直区域到光子晶体波导高效耦合的技术。结果表明:在相位匹配条件下,从自准直区域传播到耦合区域的的电磁波可以有效的分束到两个周期性介质波导中,同时能够弯曲任意角度,而且透射率保持在90%以上。最后,在设计的分束器基础上提出了一种增大点源和像点之间距离的方法。
The self-collimating and directional coupling effect of two-dimensional photonic crystal is used to design a beam splitter consisting of a self-collimating region, a coupling region and two periodic dielectric waveguides. By using the plane wave expansion method, the coupling region The coupling length was calculated. At the same time, the time-domain finite difference method was used to simulate the transmission characteristics of electromagnetic waves. The steady-state electric field distribution was obtained. The coupling of light waves from self-collimation region to photonic crystal waveguide was discussed. The results show that the electromagnetic wave propagating from the self-collimation region to the coupling region can be effectively split into two periodic dielectric waveguides under the condition of phase matching, meanwhile, the electromagnetic wave can be bent at any angle and the transmittance is maintained at over 90%. Finally, a method of increasing the distance between point source and image point is proposed based on the designed beam splitter.