High performance tunable filter based on one dimensional photonic crystal

A tunable optical filter based on one-dimensional photonic crystal with the structure (AB(1))B-n(2)(AB(1))(n) is designed. The optical transmission properties of the filter are studied by the characteristic matrix method and tight-binding theory. The simulation results show that the filtering properties, such as the central wavelength, the quality factor (Q-factor), the channel number and the transmission peak (TP), can be adjusted by the thickness of B-2, the periodic number n, the refractive index of B-2 and so on. It is found that the thickness of the material B-2 has great influence on the filtering properties, which not only can adjust the central wavelength, TPs and the Q-factor of TP, but also can realize the switching of single, double and multi-channel filters. Especially, if (AB(1))B-n(2)(AB(1))(n) is chosen as a unit cell to design the structure [(AB(1))B-n(2)(AB(1))(n)](m), the width of the photonic band gaps (PBGs) will increase, and the other m-1 comb-like TPs with high quality will appear at the right edge of the PBG. When n = 4 and m = 9, the transmission and Q- factor of the leftmost TP would be up to 1 and 71400, respectively. The results have reference values for designing tunable filter with high quality.