Wide-angle spectrally selective absorbers and thermal emitters based on inverse opals
| Autor: | Shahsafi, Alireza, Joe, Graham, Brandt, Soeren, Shneidman, Anna V., Stanisic, Nicholas, Xiao, Yuzhe, Wambold, Raymond, Yu, Zhaoning, Salman, Jad, Aizenberg, Joanna, Kats, Mikhail A. |
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| Rok vydání: | 2019 |
| Předmět: | |
| Druh dokumentu: | Working Paper |
| Popis: | Engineered optical absorbers are of substantial interest for applications ranging from stray light reduction to energy conversion. We demonstrate a large-area (centimeter-scale) metamaterial that features near-unity frequency-selective absorption in the mid-infrared wavelength range. The metamaterial comprises a self-assembled porous structure known as an inverse opal, here made of silica. The structure's large volume fraction of voids, together with the vibrational resonances of silica in the mid-infrared spectral range, reduce the metamaterial's refractive index to close to that of air and introduce considerable optical absorption. As a result, the frequency-selective structure efficiently absorbs incident light of both polarizations even at very oblique incidence angles. The absorber remains stable at high temperatures (measured up to ~900 degrees C), enabling its operation as a frequency-selective thermal emitter. The excellent performance of this absorber/emitter and ease of fabrication make it a promising surface coating for passive radiative cooling, laser safety, and other large-area applications. Comment: Main text + supplementary information |
| Databáze: | arXiv |
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