Near-complete transmission through subwavelength hole arrays in phonon-polaritonic thin films

We report that phonon-polaritonic thin films with a periodic array of subwavelength holes allow near-complete transmission in the polariton gap where a homogeneous film completely suppresses transmission. We find that both propagating modes inside the subwavelength holes and surface resonances on the film interfaces play a crucial role in the transmission behavior. In the frequency range where both occur simultaneously, they interfere destructively and completely suppress transmission. When both mechanisms are spectrally separated, each individually results in enhanced transmission.