All-dielectric diamond-based metasurface mirrors with thermal management capabilities for high-power laser applications

Low-loss, high-reflection mirrors are critical components in high-power laser systems. Conventional multilayer mirrors based on silicon or silica coatings are prone to thermal deformation and damage under intense laser irradiation. In 2022, H. Atikian et al. [Nat. Commun.13, 2610 (2022)10.1038/s41467-022-30335-2] proposed a dielectric metasurface mirror fabricated by etching nanostructures directly into single-crystal diamond substrates, circumventing coating limitations. However, the high cost and complexity of patterning diamond hinder the practical adoption of all-diamond metasurfaces. Here, we present an innovative material decoupling strategy for dielectric metasurface mirrors. Our design combines a single-crystal diamond substrate, providing exceptional thermal dissipation, with optically functional nanostructures composed of silicon gratings and silica dielectric layers. This approach decouples the stringent thermal management requirements (addressed by diamond) from the nanofabrication process (simplified using Si/SiO₂ structures). Furthermore, we quantitatively compare the thermal performance of diamond-based and silicon-based thin-film gratings, demonstrating diamond's superior thermal conductivity as a key enabler for high-power metasurface mirrors.