Skew-scattering Pockels effect and metallic electro-optics in gapped bilayer graphene

TL;DR

This paper explores strong metallic electro-optic effects arising from non-Drude carrier dynamics, especially skew-scattering and the 'Snap' effect, in layered 2D materials like gapped bilayer graphene, enabling significant terahertz modulation.

Contribution

It identifies and analyzes the dominant skew-scattering and 'Snap' effects in metallic EO behavior, proposing gapped bilayer graphene as a new platform for terahertz electro-optic applications.

Findings

Metallic Pockels and Kerr effects can produce non-reciprocal birefringence.

Field-induced modulation of transmission and reflection is significant.

Gapped bilayer graphene exhibits pronounced EO coefficients in the terahertz range.

Abstract

We argue that a range of strong metallic electro-optic (EO) effects can be naturally realized from non-Drude dynamics of free carriers in metals. In particular, in clean metals we identify skew-scattering and a "Snap" (third-order derivative of velocity) dominating the Pockels and Kerr EO behavior of metals in the clean limit. Strikingly, we find that both Pockels and Kerr EO in metals play critical roles in metallic EO phenomena: for instance, metallic Pockels and Kerr EO effectively compete to produce a field-activated birefringence that is non-reciprocal in applied DC fields. Similarly, both contribute to sizeable field-induced modulations to transmission and reflection across a range of frequencies. We find metallic EO effects can be naturally realized in layered 2D materials such as gapped bilayer graphene producing pronounced values of EO coefficients in the terahertz -- an interesting new metallic platform for terahertz electro-optic modulation.