Asymmetric transmission from a 2D PT-symmetric honeycomb nanostructure

We propose a simple realization of a 2-dimensonal (2D) PT-symmetric photonic structure: a honeycomb arrangement of alternating cylinders with gain or loss in a dielectric background. The structure provides a periodic modulation of the refractive index on the wavelength scale, which combined with an anti-symmetric gain/loss distribution on the same scale, leads to non-reciprocal light coupling at resonance frequencies. Numerical simulations show asymmetric right-left transmission of light beams.