Plasmon exciton coupling enhances second order nonlinear response in borophene ZnO hybrid structures

TL;DR

This paper demonstrates that plasmon exciton coupling in borophene-ZnO heterostructures significantly enhances second-order nonlinear optical responses, enabling efficient frequency conversion at the nanoscale.

Contribution

It introduces a novel hybrid system combining borophene and ZnO to achieve resonant nonlinear optical enhancement through plasmon exciton coupling.

Findings

Two orders of magnitude enhancement in cathodoluminescence at 400 nm and 800 nm.

Emergence of a strong second harmonic signal with quadratic power dependence.

Resonance near 800 nm attributed to nonlinear plasmon exciton coupling.

Abstract

Nonlinear optical processes in low dimensional materials are often weak or symmetry forbidden, limiting their use in nanoscale light sources and on chip frequency conversion. Here, we show that combining two weakly nonlinear systems, anisotropic borophene and excitonic zinc oxide, yields an enhanced and resonant nonlinear response. In borophene ZnO heterostructures, cathodoluminescence reveals a two orders of magnitude enhancement at 400 nm and 800 nm, due to an enhanced two photon absorption process. Under tunable near infrared excitation, a clear second harmonic signal emerges with quadratic power dependence and strong resonance near 800 nm. We attribute this to nonlinear plasmon exciton coupling, which reshapes the excitonic response and enables efficient hybrid pathways for frequency conversion. These results establish anisotropic plasmon exciton hybridization as a route to controlling nonlinear optical responses in low dimensional heterostructures.