Optical forces on an oscillating dipole near VO$_2$ phase transition

TL;DR

This paper studies how optical forces on oscillating dipoles near VO$_2$ films change with temperature, showing phase transition effects can switch forces from attraction to repulsion, enabling new light-matter control methods.

Contribution

It demonstrates the influence of VO$_2$ phase transition on optical forces, incorporating thermal hysteresis effects for potential applications in light-matter interaction control.

Findings

Optical forces can switch from attractive to repulsive with temperature changes.

VO$_2$ phase transition effects are evident in near-field optical forces.

Thermal hysteresis impacts the behavior of optical forces near phase transition.

Abstract

We investigate optical forces on oscillating dipoles close to a phase-change vanadium dioxide (VO$_2$) film, which exhibits a metal-insulator transition around $340$ K and low thermal hysteresis. This configuration is related to one composed of an excited two-level quantum emitter and we employ a classical description to capture important aspects of the radiation-matter interaction. We consider both electric and magnetic dipoles for two different configurations, namely, with the dipole moments parallel and perpendicular to the VO$_2$ film. By using Bruggeman theory to describe the effective optical response of the material, we show that, in the near-field regime, the force on the dipoles can change from attractive to repulsive just by heating the film for a selected frequency range. We demonstrate that the thermal hysteresis present in the VO$_2$ transition clearly shows up in the behavior of the optical forces, setting the grounds for alternative approaches to control light-matter interactions using phase-change materials.