Optical properties of Tamm states in metal grating-one dimensional photonic crystal structures

Here, we present the design and fabrication details of a metal grating-one dimensional photonic crystal (1DPhC) structure that can efficiently couple the normal incident light into the 1DPhCs. We implement this by designing a silver (Ag) nano-grating on the 1DPhC which consists of 10 bilayers of SiO2/TiO2 thin films on a silicon substrate. Ag coated 1DPhC shows a sharp dip in the reflectivity within the photonic stop band, which is a distinct signature of the excitation of Tamm states at the interface of metal-1DPhC boundary. Reflection spectrum of Ag grating–1DPhC structure shows that the Tamm state is modified in the presence of the Ag grating, giving rise to a surface state in the vicinity of the Tamm resonance. The experimental results obtained are well supported by simulations which provide the field distributions for the Tamm resonance and the surface state.