Probing of valley polarization in graphene via optical second-harmonic generation

TL;DR

This paper develops a theoretical framework for using optical second-harmonic generation as a sensitive method to detect valley polarization in graphene, which is crucial for advancing ultrafast valleytronics applications.

Contribution

It provides a comprehensive single-particle theory linking valley polarization to second-harmonic generation in graphene, enabling new experimental detection methods.

Findings

Valley polarization induces measurable second-harmonic signals.

The theory suggests optical SHG as a sensitive probe for valley polarization.

Potential applications in ultrafast valleytronics development.

Abstract

Valley polarization in graphene breaks inversion symmetry and therefore leads to second-harmonic generation. We present a complete theory of this effect within a single-particle approximation. It is shown that this may be a sensitive tool to measure the valley polarization created, e.g., by polarized light and, thus, can be used for a development of ultrafast valleytronics in graphene.