鉴于波导定向耦合器在集成光路以及光电集成方面的广泛应用, 提出了一种基于光子晶体波导间高效耦合的光子晶体定向耦合器。通过主波导和耦合波导间的耦合, 可以实现对波长为1 490 nm和1 550 nm电磁波的高效分光。在将器件长度控制在30 μm左右的同时, 其总效率高达93.05%。另外, 发现主波导和耦合波导间介质柱结构参数对电磁波的耦合周期有着极大的影响。并通过将介质柱沿z方向拉伸0.1a(a为晶格周期), 设计了工作波长为1 530 nm和1 540 nm的光子晶体定向耦合器, 器件长度仅为60 μm。通过拉伸介质柱的纵向长度, 可以大幅减小耦合周期, 这对缩小器件体积以及实现更为密集的波分复用有着重要的意义。

Considering the significant value of the directional coupler on the integrated optical circuit and optical electronic integrated circuits, two dimensional photonic crystal directional coupler depended on the photonic crystal waveguide was designed. Via the coupling between the bus waveguide and the coupling waveguide, the high efficiency beam splitter of the electromagnetic wave with the wavelength of 1 490 nm and 1 550 nm was realized. The transmission efficiency reached about 93.5%, and the length of the device can be controlled under 30 μm. In addition, it was found that the coupling period was sensitive to the structure parameters of the rods located between the bus waveguide and the coupling waveguide. By stretching the length of the rods to about 0.1a(a is the lattice period) along z direction, the directional coupler with the working wavelength of 1 490 nm and 1 550 nm was designed. The length of the device was about 60 μm, which was much shorter than that without optimizing. The coupling period can be dramatically shorten by stretching the longitudinal length of the rods, which is of crucial value on the decreasing the volume of the device and the achievement of the denser wavelength division multiplexing.