Nonlinear optical heating of all-dielectric super-cavity: efficient light-to-heat conversion through giant thermorefractive bistability

TL;DR

This paper introduces a new analytical model and design strategy for nonlinear optical heating in dielectric super-cavities, enabling efficient light-to-heat conversion through thermorefractive bistability by exploiting giant nonlinear effects.

Contribution

It develops a novel critical coupling condition for nonlinear regimes and designs a nanoparticle with a super-cavity mode for optimized optical heating.

Findings

Derived a new critical coupling condition for nonlinear optical heating.

Designed a nanoparticle supporting a quasi-BIC mode for efficient heating.

Demonstrated potential for enhanced nonlinear optical experiments.

Abstract

Optical heating of resonant nanostructures is one of the key issues in modern nanophotonics, being either harmful or desirable effect depending on the applications. Despite a linear regime of light-to-heat conversion is well-studied both for metal and semiconductor resonant systems generalized as critical coupling condition, the clear strategy to optimize optical heating upon high-intensity light irradiation is still missing. In this work, we propose a simple analytical model for such problem taking into account material properties changes caused by the heating. It allows us to derive a new general critical coupling condition for the nonlinear case, requiring counterintuitive initial spectral mismatch between the pumping light frequency and resonant one. Basing on the suggested strategy, we develop an optimized design for efficient nonlinear optical heating, which employs a cylindrical nanoparticle supporting quasi bound state in the continuum mode (quasi-BIC or so-called `super-cavity mode') excited by the incident azimuthal vector beam. Our approach provides a background for various nonlinear experiments related to optical heating and bistability, where self-action of the intense laser beam can change resonant properties of the irradiated nanostructure.