Seminarium Fotoniki

One of the exceptional features of non-Hermitian systems is the unidirectional wave interactions. At a particular (exceptional) point the situation can be achieved, that the external radiation is efficiently coupled into the system, but the internal radiation cannot escape backwards. We realize this idea in non-Hermitically modulated thin films, consisting of a Hermitian part - the periodic corrugation of the surfaces of a film, and a non-Hermitian part - the modulation of losses along the film. We prove numerically and demonstrate experimentally that the incident radiation, coupled with such a non-Hermitian thin film, is unidirectionally trapped into a planar mode of the film, does not escape from the film (or escape weakly due to experimental imperfections), and is efficiently absorbed there.