Unconventional optical Tamm defect states in metal-terminated opal photonic crystals

Optical Tamm surface states are formed in 3-dimensional photonic crystals coated by thin metal films. These states appear in registry with diffraction resonances and localize the electromagnetic energy in resonators formed by diffraction mirrors of lattice planes and metal semishells. Tamm defect states provide the bypass for light in the spectral range of photonic stop-bands and thus reduce the efficiency of the Bragg diffraction resonances. In spite of hidden nature of this effect, its magnitude is comparable to the extraordinary transmission associated with tunneling of surface plasmon polaritons, which are simultaneously excited at surfaces of corrugated metal film coating.