Controlling the coexistence of structural phases and the optical properties of gallium nanoparticles with optical excitation

TL;DR

This paper demonstrates reversible optical control over phase transitions in gallium nanoparticles, enabling dynamic coexistence of phases and significant optical property changes with minimal energy input.

Contribution

It introduces a method to reversibly control structural phases of gallium nanoparticles using low-power optical excitation at telecom wavelengths.

Findings

Reversible phase transformations observed at 1.55 μm excitation.

Control achieved with only tens of nanowatts per particle.

Phase equilibrium time in the microsecond range.

Abstract

We have observed reversible structural transformations, induced by optical excitation at 1.55 micrometer, between the beta, gamma and liquid phases of gallium in self-assembled gallium nanoparticles, with a narrow size distribution around 50 nm, on the tip of an optical fiber. Only a few tens of nanowatts of optical excitation per particle are required to control the transformations, which take the form of a dynamic phase coexistence and are accompanied by substantial changes in the optical properties of the nanoparticle film. The time needed to achieve phase equilibrium is in the microsecond range, and increases critically at the transition temperature.