Abstract
All-dielectric optical metasurfaces with high quality (Q) factors have been hampered by the lack of simultaneously lossless and high-refractive-index materials over the full visible spectrum. In fact, the use of low-refractive-index materials is unavoidable for extending the spectral coverage due to the inverse correlation between the bandgap energy (and therefore the optical losses) and the refractive index (n). However, for Mie resonant photonics, smaller refractive indices are associated with reduced Q factors and low mode volume confinement. Here, symmetry-broken quasi bound states in the continuum (qBICs) are leveraged to efficiently suppress radiation losses from the low-index (n approximate to 2) van der Waals material hexagonal boron nitride (hBN), realizing metasurfaces with high-Q resonances over the complete visible spectrum. The rational use of low- and high-refractive-index materials as resonator components is analyzed and the insights are harnessed to experimentally demonstrate sharp qBIC resonances with Q factors above 300, spanning wavelengths between 400 and 1000 nm from a single hBN flake. Moreover, the enhanced electric near fields are utilized to demonstrate second-harmonic generation with enhancement factors above 10(2). These results provide a theoretical and experimental framework for the implementation of low-refractive-index materials as photonic media for metaoptics.
| Item Type: | Journal article |
|---|---|
| Faculties: | Physics |
| Subjects: | 500 Science > 530 Physics |
| URN: | urn:nbn:de:bvb:19-epub-106864-3 |
| ISSN: | 0935-9648 |
| Language: | English |
| Item ID: | 106864 |
| Date Deposited: | 11. Sep 2023, 13:44 |
| Last Modified: | 29. Sep 2023, 20:06 |
| DFG: | Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - 491502892 |
| DFG: | Gefördert durch die Deutsche Forschungsgemeinschaft (DFG) - 390776260 |
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