Lawrence Berkeley National Laboratory

Many technological applications in photonics require devices to function reliably under extreme conditions, including high temperatures. To this end, materials and structures with thermally stable optical properties are indispensable. State-of-the-art thermal photonic devices based on nanostructures suffer from severe surface diffusion-induced degradation, and the operational temperatures are often restricted. Here, we report on a thermo-optically stable superabsorber composed of bilayer refractory dielectric materials. The device features an average absorptivity ∼95% over >500 nm bandwidth in the near-infrared regime, with minimal temperature dependence up to 1500 °C. Our results demonstrate an alternative pathway to achieve high-temperature thermo-optically stable photonic devices.