Thermally Reconfigurable Metasurfaces: From Linear Wavefront Control to Nonlinear and Chemical Functionality

Resonant metasurfaces concentrate light into subwavelength volumes where even modest temperature changes can shift, reshape, or extinguish spectral features─turning heat into a powerful control knob. This Review presents a unified perspective on thermo-optical metasurfaces, showing how photothermal transduction and temperature-dependent refractive indices connect a single physical mechanism to diverse functionalities. We trace this connection from wavefront and spectral control in the linear regime to bistability, nonreciprocity, and modulation of nonlinear and quantum optical processes. We further highlight emerging applications at the interface of nanophotonics and chemistry, where thermally generated temperature fields and tunable resonances can control reaction environments, enhance infrared molecular signatures, and switch polaritonic coupling. By comparing material platforms and resonance architectures, we identify key opportunities and challenges that will guide the development of thermo-optical metasurfaces for reconfigurable photonics, spectroscopy, and chemistry.