Monolithic SiC collimating metalens with PSO-WTPS optimisation for extreme high-temperature applications

Abstract

Nanostructures utilised in collimating metalenses are unsuitable for extremely high-temperature applications, primarily due to their inadequate thermal stability and thermal mismatch with the substrate. While high-temperature-resistant materials have been widely adopted to improve the thermal stability of metalens structures, there remains a need for active and precise compensation to mitigate thermally induced phase drift. In this paper, a monolithic silicon carbide (SiC) metalens with excellent thermal stability is introduced. We propose a Particle Swarm Optimisation (PSO)-based Wide-Temperature Phase Stabilisation (PSO-WTPS) strategy to optimise model parameters. This approach compensates for phase drift induced by temperature-dependent refractive index variations and thermal expansion, thereby suppressing the degradation of the metalens’ operational performance at elevated temperatures. Simulations indicate that over the temperature range from 300 K to 1273 K, the drift in the collimation divergence angle of the metalens remains below 0.13 mrad, while the transmittance exceeds 75%. This research facilitates the design and performance prediction of high-temperature collimators.