Resonant transmission in a dielectric photonic crystal with a thin metallic coating

In this work, the resonant optical transmission (ROT) in a dielectric-dielectric photonic crystal (DDPC) with a thin metallic coating operating in the visible is theoretically investigated. First, the phenomenon of ROT is shown to occur at the frequency within the photonic band gap (PBG). To obtain a significant ROT, there is an optimum stack number for the DDPC and an optimum thickness of thin metal layer. The phenomenon of ROT can be explained by the condition of impedance matching. Second, the effect of different metallic films on the ROT is also examined. It is found that the frequency of ROT is blue-shifted for the metal with a larger plasma frequency. Finally, the behavior of ROT is investigated as a function of angle of incidence for both TE and TM waves. The frequency of ROT is blue-shifted as the angle of incidence increases for TE and TM waves. In TM wave, it is of interest to find that there are two ROTs within the photonic band gaps. The analysis made is based on the use of the transfer matrix method.