对称和非对称结构1维光子晶体的滤波特性

Filtering properties of 1-D photonic crystals with symmetrical and asymmetrical structures

为了得到1维光子晶体新的滤波特性,并把这种特性应用到滤波器的设计中,采用传输矩阵法计算了对称和非对称结构1维光子晶体的滤波特性,同时还分析了不同的折射率比对两种结构1维光子晶体滤波特性的影响。结果表明,对称结构1维光子晶体可实现窄带滤波功能,该结构的滤波器对入射角的选取是有限制的,不适于微弱信号的检测;且当多层膜系外层为高折射率时,透射带宽要窄些。非对称结构光子晶体则具有带阻滤波特性,与对称结构1维光子晶体最大的不同是改变膜系中高低折射率材料的顺序,其滤波特性没有变化。理论分析和数值模拟结果为设计窄带滤波器和带阻滤波器提供了依据。

In order to obtain the filtering characteristics of photonic crystals with symmetrical structure and asymmetrical structure, the influence of refractive index ratio for both the structures was analyzed based on the transfer matrix method. The results indicate that the photonic crystals with symmetrical structure have narrow-band filtering characteristics at selected incident angles. However, it is not suitable for weak signal detection. Their transmission bandwidth is narrower when the outer layer of multi-layer coating films is at high refractive index. The photonic crystals with asymmetrical structure have band-stop filtering characteristics and the characteristics maintain the same for any sequence of high or low refractive index. The theoretical analysis and simulation results provide the theory for developing narrow-band and band-stop filters.