Ultranarrow and Wavelength-Tunable Thermal Emission in a Hybrid Metal–Optical Tamm State Structure
Zhiyu Wang, J. Kenji Clark, Ya‐Lun Ho, Sébastian Volz, Hirofumi Daiguji, Jean‐Jacques Delaunay
Abstract
Spectral selective thermal emitters are promising technological components due to their efficiency, large range of available emission wavelengths, simplicity, and long lifetime. Despite intensive effort into narrowband thermal emitters using surface plasmon polaritons, surface phonon polaritons, and Tamm plasmons, material losses have limited the potential quality factors, with the highest reported value being 200. Here, by combining a metallic mirror and an optical Tamm state structure, we propose a hybrid structure that realizes narrowband and wavelength-tunable thermal emission. In the proposed structure, large energy can be stored between the lossless DBRs (SiO2/Ge), thus, drastically reducing metal losses. The metallic mirror is set at the bottom of the proposed structure to reduce the transmission losses and guarantee a large absorption/emission. This metal–optical Tamm state structure achieves experimentally a thermal emittance peak with a quality factor of over 750 at a wavelength of around 4.5 μm. Moreover, taking advantage of the temperature sensitivity of Ge, the thermal emission wavelength can be tuned by adjusting the operating temperature between 100 and 150 °C. Both the high-quality factor and the wavelength-tunable properties demonstrate its suitability as a practical narrowband light source.