Skew scattering and ratchet effect in photonic graphene

TL;DR

This paper provides a theoretical analysis of skew scattering and the resulting ratchet effect in photonic graphene with triangular defects, revealing how symmetry breaking leads to unidirectional fluxes in exciton-polariton systems.

Contribution

It introduces a detailed theoretical framework for skew scattering and ratchet effects in photonic graphene with specific defect geometries, expanding understanding of symmetry-breaking phenomena in photonics.

Findings

Skew scattering causes asymmetry in exciton-polariton scattering.

Triangular defects induce a ratchet effect with unidirectional flux.

Numerical solutions reveal microscopical details of the scattering process.

Abstract

The present paper is devoted to a comprehensive theoretical study of asymmetric (skew) scattering in photonic graphene, with the main focus on its realization with semiconductor microcavity exciton-polaritons. As an important consequence of the skew scattering, we prove the appearance of the ratchet effect in this system. Triangular defects in the form of missing micropillars in a regular honeycomb lattice are considered as ones that break the spatial inversion symmetry, thus providing the possibility of the ratchet effect. By means of the numerical solution of the effective Schr\"odinger equation, we provide microscopical insight into the process of skew scattering and determine indicatrices, cross-sections, and asymmetry parameters. In a system with multiple coherently oriented triangular defects, a macroscopic ratchet effect occurs as a unidirectional flux upon noise-like initial conditions. Our study broadens the concept of ratchet phenomena in the field of photonics and optics of exciton-polaritons.