2D-Material-Assisted Bistable Switching of Gap Plasmons Disclosed By Femtosecond Pulse Scattering Spectra

TL;DR

This study demonstrates a bistable switching mechanism in gap plasmons facilitated by 2D materials like graphene and MoS2, using femtosecond pulse scattering spectra, revealing potential for energy-efficient nonlinear plasmonic devices.

Contribution

The paper introduces a novel bistable switching behavior in gap plasmons assisted by 2D materials, characterized by femtosecond pulse scattering and theoretical modeling of nonlinear feedback mechanisms.

Findings

Abrupt changes in scattering linewidth and intensity with laser power.

Universal switching threshold at 0.14% four-wave mixing efficiency.

Bistability driven by nonlinear gap currents and high-order wave mixing.

Abstract

Nanosphere-on-mirror plasmonic antennas, each having a monolayer graphene or MoS2 sheet in the gap, were pumped with a femtosecond laser. Abrupt turnings in the scattering linewidth and peak intensity trends as the laser power changed were experimentally observed. Theoretical modelling of dynamic plasmon evolvement attributes the turning to transitioning between two plasmon states, with a universal switching threshold of four-wave mixing efficiency around 0.14%. This bistability is rendered by a strong feedback from the nonlinear gap current to the gap plasmons, and involvement of both four and high-order wave mixing. This work reveals a pathway to making energy efficient nonlinear plasmonic elements.