# Chiral selection rules for multi-photon processes in two-dimensional honeycomb materials

## TL;DR

This paper explores the chirality-dependent optical selection rules in 2D honeycomb materials, generalizing to multi-photon processes, and demonstrates their experimental verification and potential for imaging applications.

## Contribution

It provides a symmetry-based generalization of chirality-dependent selection rules to multi-photon processes in 2D materials, supported by experimental validation.

## Key findings

- Agreement between theory and experiment for second and third harmonic generation
- Phase relations can be used for domain imaging in monolayers
- Chiral selection rules influence multi-photon optical processes

## Abstract

We examined the chirality dependent optical selection rules in two-dimensional monolayer materials with the honeycomb lattice, and based on symmetry argument, we generalized these rules to multi-photon transitions of arbitrary orders. We also presented the phase relations between incident and outgoing photons in such processes. The results agreed nicely with our experimental observations of second and third harmonic generations. In particular, we demonstrated that the phase relation of chiral second harmonic generation can serve as a handy tool for imaging domains and domain boundaries of these monolayers. Our results can benefit future studies on chirality related optical phenomena and opto-electronic applications of such materials.

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Source: https://tomesphere.com/paper/1902.03401