VO2 Nanocrystals for Designer Phase-Change Metamaterials

TL;DR

This paper demonstrates that VO2 nanocrystals can be used to create tunable phase-change metamaterials with dynamically adjustable optical properties, enabling new design possibilities for low-loss, actively controlled light manipulation.

Contribution

The study introduces a method to dynamically tune multipolar resonances in VO2 nanocrystals, advancing phase-change metamaterials with enhanced optical tunability.

Findings

VO2 nanocrystals exhibit tunable multipolar resonances during insulator-metal transition.

Effective medium theory shows distinct optical properties compared to unpatterned VO2.

The resulting metamaterials enable actively controlled light scattering.

Abstract

Subwavelength nanoparticles can support electromagnetic resonances with distinct features depending on their size, shape and nature. For example, electric and magnetic Mie resonances occur in dielectric particles, while plasmonic resonances appear in metals. Here, we experimentally demonstrate that the multipolar resonances hosted by VO2 nanocrystals can be dynamically tuned and switched thanks to the insulator-to-metal transition of VO2. Using both Mie theory and Maxwell Garnett effective medium theory, we retrieve the complex refractive index of the effective medium composed of a slab of VO2 nanospheres embedded in SiO2 and show that such a resulting metamaterial presents distinct optical tunability compared to unpatterned VO2. We further show that this provides a new degree of freedom to design low-loss phase-change metamaterials with designer optical tunability and actively controlled light scattering.