Discrete Talbot effect in modulated lattices with PT symmetric perturbations

Abstract

We demonstrate both theoretically and numerically that the periodic self-imaging phenomenon of light patterns with certain input periods can be effectively realized in a three-layered optical lattice with parity–time symmetric modulations, which can introduce a modulation phase to the lattice structure. By varying the ratio of coupling coefficients, the Talbot distance can be engineered, which can be further tuned by adjusting the modulation phase. The Talbot effect occurs only if the modulation phase belongs to a specific set: {±π/3,±π/2,±2π/3,±π}.