Nonlinear optical response of Type-II Weyl fermions in two dimensions

TL;DR

This paper develops a theoretical model to analyze the nonlinear optical behavior of 2D Weyl materials with tilted cones, highlighting the emergence of even harmonics and polarization effects, with potential applications in photonic sensing.

Contribution

It introduces a novel theoretical framework for understanding the nonlinear optical response of 2D Weyl materials with tilted cones, emphasizing control mechanisms and device applications.

Findings

Tilted Weyl cones cause even harmonic generation.

Nonlinear response shows strong polarization dependence.

Potential for designing novel photonic sensors.

Abstract

We present a theoretical model to study the nonlinear optical response of materials with a low-energy spectrum characterised by strongly tilted, type-II, Weyl cones in two dimensions, which we call 2D Weyl materials. Our findings reveal that the tilted nature of the Weyl cones is responsible for the appearance of even harmonics in the nonlinear signal, as well as its strong polarisation dependence. We discuss how it is possible to control such nonlinear response and envision how 2D Weyl materials can be used to realise novel photonic devices for sensing applications.