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

• Published in: Nanophotonics (Berlin, Germany) Germany), 2022-09, Vol.11 (17), p.3981-3991
• Main Authors: Ryabov, Daniil, Pashina, Olesiya, Zograf, George, Makarov, Sergey, Petrov, Mihail
• Format: Article
• Language: English
• Subjects: bistability; bound state in the continuum; Conversion; Coupling; critical coupling; Design optimization; Heat conductivity; Laser beam heating; Light; Light irradiation; Luminous intensity; Material properties; Nanoparticles; Nanostructure; Nonlinear optics; nonlinearity; optical heating; super-cavity
• ISSN: 2192-8614; 2192-8606; 2192-8614
• DOI: 10.1515/nanoph-2022-0074

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 being well-studied both for metal and semiconductor resonant systems is generalized as a critical coupling condition, the clear strategy to optimize optical heating upon high-intensity light irradiation is still missing. This work proposes a simple analytical model for such a 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 a counterintuitive initial spectral mismatch between the pumping light frequency and the resonant one. Based on the suggested strategy, we develop an optimized design for efficient nonlinear optical heating, which employs a cylindrical nanoparticle supporting the 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.