Tunable Tamm plasmon polaritons and perfect absorption in a metal-PC cavity

We propose a metal-photonic crystal (PC) cavity structure, which had a narrow band absorption in the band-gap of PC. The electric field was strongly enhanced near the cavity when the wavelength of incident light corresponded to the absorption peak, which meant the proposed structure could generate Tamm plasmon polaritons. Through adjusting the thickness of the cavity, the wavelength of absorption peak could be tuned from ~1510 nm to ~1690 nm in this work. Meanwhile, the refractive index of the cavity also affected the absorption spectrum. Importantly, the proposed structure could realize perfect absorption at suitable conditions, and the maximum absorptance reached 0.999 95. The period number of PC and the thickness of silver film also had great influence on the absorption spectrum, which has also been investigated in this paper.