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

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.