Presentation Information
[9a-PA4-22]Visible to Near-IR Thermal Radiation Control via Toroidal Dipole Resonance in Silicon Nanodisk Arrays
〇(B)Shota Hosoi1, Kono Shintaro1, Sugimoto Hiroshi1, Fujii Minoru1 (1.Kobe Univ.)
Keywords:
thermal radiation,metasurface
Recent studies have explored wavelength-selective thermal emission using photonic crystals and metasurfaces. However, blackbody radiation in the visible and short-wave infrared (SWIR) regions is intrinsically weak at the operating temperatures of semiconductors and ceramics (<1000 K), making efficient thermal emission difficult to achieve. Crystalline silicon (Si) is a promising material because of its high refractive index and low extinction coefficient in the visible–near-infrared region. In addition to conventional Mie resonances, ultrathin Si nanodisk arrays support toroidal dipole (TD) resonances that strongly localize electromagnetic fields inside the structure and enhance optical absorption. In this study, TD resonances were applied to thermal radiation control, and wavelength-selective narrowband thermal emission was demonstrated. Reflection and thermal emission spectra of Si nanodisk arrays were measured using microscopic spectroscopy at elevated temperatures. A characteristic Fano resonance associated with the TD mode was observed near 800 nm at 600 °C. The thermal emission spectrum exhibited a narrowband peak at the TD resonance wavelength with suppressed long-wavelength emission. These results demonstrate that TD-resonance-enhanced absorption provides an effective approach for realizing narrowband visible–near-infrared thermal emitters under practical operating temperatures.