根据时域耦合模理论(Coupled-Mode Theory, CMT)分析了基于近长方环腔谐振器与波导侧边耦合结构的光子晶体带阻滤波器(Photonic Crystal Stop-Band Filter, PCSBF) 的工作状况, 得到了其正规化带阻损耗率L、腔失谐因子|ω-ω0|τ0、腔正规化损耗率Lc、正规化反射率R以及正规化传输率T之间的函数关系, 并探索了PCSBF的带阻损耗工作机制。用时域有限差分(Finite Difference Time Domain, FDTD)法研究了1450~1750 nm波段的PCSBF滤波性能。通过改变PCSBF结构中3×n(3≤n≤9)近长方腔的大小或腔内部柱半径都能调节该结构输出的正规化功率谱带阻波段。在输出的功率谱中采集了34个平均宽度为5817 nm的较宽带阻波段。信号传输强度损耗的平均值不小于8035 dB。结果表明, 该结构的波长阻带具有可调性宽、正规化带阻损耗率高等特点。根据实际需求, 通过改变PCSBF结构设计来调节功率输出谱, 可以有效滤除不需要的波长信号, 从而保证光纤通信系统和集成光路工作的稳定性。因此, 这种微型带阻元件在光集成和光通信等领域具有潜在应用价值。

According to the time domain coupled mode theory, the working conditions of the photonic crystal stop-band filter with a side coupling structure of the waveguide and the approximate rectangular ring cavity resonator are analyzed. The function relationships of normalized stop-band loss L, cavity detuning factor|ω-ω0|τ0, cavity normalized loss Lc, normalized reflection R and normalized transmission T are obtained, and the stop-band loss mechanism of PCSBF is explored. The filtering performance of PCSBF within the wavelength range of 1450--1750 nm is studied by using the finite difference time domain method, which shows that the stop-bands of the output normalized power spectrum can be adjusted by changing the size of 3×n(3≤n≤9)approximate rectangular ring cavities or by changing the radius of inner rods in this PCSBF structure. 34 wide stop-bands whose average width is 5817 nm are collected from the PCSBF power spectrum, and the average value of these stop-bands signal strength decay is not less than 8035 dB. The results show that the stop-band of the structure has the characteristics of wide tenability, high normalized loss and so on. According to the actual demand, changing the PCSBF structure design to adjust the power output spectrum can effectively filter the unwanted wavelength signal, thus ensuring the stability of optical fiber communication system and integrated optical path. Therefore, this miniature stop-band component has potential application value in the optical integration, the optical communication and other fields.