Metasurfaces for Radiative Cooling

This thesis investigates microstructured radiative cooling materials fabricated using femtosecond laser direct writing. It covers the design principles, fabrication methods, characterisation, and performance of laser-machined metasurfaces on sapphire, metals, silicon, and a polymer-based cooling film. The results show that laser-induced patterns enhance thermal emission and reduce mid-infrared reflectance through both structural and chemical surface modifications, improving radiative cooling efficiency. Different laser beam types and machining parameters were studied to control micro- and nanostructure formation. A scalable polymer film was also demonstrated for practical cooling applications. The research advances understanding of light–matter interactions and supports development of novel cooling technologies.