Abstract:
We propose a 2-dimensonal PT-symmetric photonic honeycomb structure that supports chiral Block-like modes being its excitation input and frequency dependent. We show that while the fundamental resonant frequency excites the counter-clockwise mode, the clockwise mode is excited at the corresponding second harmonic frequency from the same input channel. The geometry is derived as the simplest nontrivial extension from 1-dimensional PT-symmetric systems to provide asymmetric coupling between harmonic wave components of the electromagnetic field. The PT-symmetric honeycomb is generated by a closed set of three lattice vectors that enable the simultaneous resonance of two disjoint triads of wavevectors in a circular coupling. As a basic effect, we numerically show the measurable asymmetric transmission of Gaussian light beams incident on such a finite-sized structure with a hexagonal shape, at the fundamental and second harmonic resonant frequencies.