利用二维正方晶格介质柱型光子晶体(PC), 设计了一款由4个线性渐变型微腔和异质结构光子晶体反射器组成的多信道下路滤波器。利用平面波展开法(PWE)以及二维时域有限差分法(2D-FDTD)分析了该异质结构滤波器的工作机制, 并进一步探究了微腔参考面与异质结界面之间距离对下路效率的影响。研究表明, 滤波器中的异质结反射器可以实现接近100%的反射, 从而大幅度地提高了三端口滤波器的滤波效率。设计的多信道滤波器各个通道都能有效地实现下路滤波功能, 其信道间隔为10 nm, 滤波效率均在90%以上, 透射谱半高宽均在0.54 nm以下, 实现了较高的品质因子特性。该滤波器尺寸只有15.15 μm×13.91 μm, 且滤波效率很高, 适于在波分复用系统中进行复用与解复用, 在未来光路集成应用中具有良好的应用前景。

On the basis of the two-dimensional square lattice photonic crystal with dielectric rods, a novel multi-channel drop filter consisting of four linear gradient microcavities and a heterophotonic crystal reflector was designed. The working mechanism of the heterophotonic crystal filter was analyzed by using Plane Wave Expansion(PWE) method and two-dimensional Finite Difference Time Domain(2D-FDTD) method, then the influence of the distance between the reference plane of microcavity and the hetero-interface on the drop efficiency was explored. The results show that the heterophotonic reflector in the filter is able to achieve 100% reflection so that to improve the drop efficiency of the three-port channel drop filter greatly. Each channel of the designed filter has the ability to drop the light wave effectively, in which the channel space is 10 nm, the rates of normalized transmission are all above 90%, and the full-widths at half-maximum(FWHM) of the transmission spectrums are all below 0.54 nm. The filter has achieved a higher quality factor and shows a compact size of 15.15 μm×13.91 μm and a high filtering efficiency. It is suitable for multiplexing and demultiplexing in a wavelengh division multiplexing system and has potential application values to integrated optics circuits.