All-Dielectric Photo-thermo-optical Metasurfaces for Thermal Landscaping at the Nanoscale

Abstract

Precise control of temperature fields at the micro- and nanoscale is essential for emerging applications in nanophotonics, catalysis, and microfluidics, yet remains difficult due to the diffusive nature of heat. While inverse-design algorithms have advanced thermoplasmonic metasurfaces, their extension to all-dielectric systems has not been explored. Here, an inverse thermal design framework is introduced for dielectric metasurfaces composed of thermo-optical amorphous silicon (a-Si) nanoresonators. By leveraging a precomputed library of absorption spectra as a function of geometry and temperature, target thermal profiles are directly mapped onto metasurfaces, enabling both uniform and complex temperature shaping. Unlike plasmonic platforms that require multi-resonator unit cells for tunability, dielectric nanoresonators provide intrinsic reconfigurability: at wavelengths where the thermo-optical coefficient is negligible (e.g., ~500 nm), absorption is temperature-invariant, whereas at other wavelengths it becomes strongly temperature-dependent, allowing illumination intensity to reshape the thermal landscape. This multifunctionality permits a single metasurface to yield distinct profiles under different excitation conditions without added structural complexity. As a proof of concept, photothermal catalysis on such metasurfaces is modeled, predicting over 30% enhancement in reaction rates. The presented framework establishes a scalable strategy for engineering nanoscale temperature fields with broad implications for catalysis, thermal management, and photothermal energy conversion.