Topologically Engineered High- Q Quasi-BIC Metasurfaces for Enhanced Near-Infrared Emission in PbS Quantum Dots.

Enhancing photoluminescence (PL) efficiency in colloidal quantum dots is pivotal for next-generation near-infrared photodetectors, imaging systems, and photonic devices. Conventional methods, especially metal-based plasmonic structures, suffer from large optical losses, which limits their practical use. Here, we introduce a quasi-bound state in the continuum (quasi-BIC) metasurface on a silicon-on-insulator platform, tailored to provide high-quality factor resonances with minimized losses. Utilizing topological charge engineering and controlled in-plane asymmetry in silicon cylinder arrays, we developed a robust quasi-BIC capable of maintaining a high Q factor across a broad angular range, achieving an experimental Q factor of 3031 at normal incidence. This approach significantly enhances near-field interactions, achieving a ≤110-fold increase in PL for PbS quantum dots at 33 K and a 41-fold enhancement at room temperature. Our findings offer a scalable, cost-effective solution for enhancing light emission in advanced optoelectronic applications.