Asymmetric localization induced by non-Hermitian perturbations with PT symmetry in photonic lattice.

We study both theoretically and numerically the asymmetric localization of lightwave in a three-layered photonic lattice with non-Hermitian perturbations. The results indicate that the gauge potential for photons can arise from the non-Hermitian perturbations, once the perturbations satisfy parity-time symmetry. Further study shows that the Peierls phase between adjacent waveguides has an important impact on the shapes of the band structures, which result in asymmetric localization of a lightwave in such a system when the wave number and Peierls phase satisfy k=ϕ=±π/2. This Letter provides a new way to control the light transmission and a feasible method to realize gauge potential for photons.

Two-dimensional non-reciprocal transmission in dynamically modulated photonic lattices.

We propose a method for realizing two-dimensional (2D) non-reciprocal (one-way) transmission of discretized light in a dynamically modulated optical waveguide array. By adjusting the phase of the modulation between the defect site and the most adjacent waveguides, asymmetric transmission in the same layer or between the first and third waveguide layers can be obtained. In particular, when the defect waveguide is lossless, 2D non-reciprocal transmission is realized perfectly.