Diffractive switching by interference in a tailored PT-symmetric grating

Abstract

We numerically study the diffraction properties of a parity-time (PT) symmetric transmission grating, which operates through a limited number of guiding modes. The interferometric operation is altered by the introduction of balanced gain and loss leading, for example, to efficient switching around the spontaneous symmetry breaking point. Furthermore, we examine the influence of the longitudinal reflections, which are not common in previous PT structures. In addition, we separately tailor the periodicities of gain and loss, so that the device remains PT symmetric. However, this gives a new way to control the mode merging phenomenon, as we obtain interactions between previously distinct modes.