High-Q Resonances Governed by the Quasi-Bound States in the Continuum in All-Dielectric Metasurfaces

Abstract

The realization of high-Q resonances in a silicon metasurface with various broken-symmetry blocks is reported. Theoretical analysis reveals that the sharp resonances in the metasurfaces originate from symmetry-protected bound states in the continuum (BIC) and the magnetic dipole dominates these peculiar states. A smaller size of the defect in the broken-symmetry block gives rise to the resonance with a larger Q factor. Importantly, this relationship can be tuned by changing the structural parameter, resulting from the modulation of the topological configuration of BICs. Consequently, a Q factor of more than 3,000 can be easily achieved by optimizing dimensions of the nanostructure. At this sharp resonance, the intensity of the third harmonic generation signal in the patterned structure can be 368 times larger than that of the flat silicon film. The proposed strategy and underlying theory can open up new avenues to realize ultrasharp resonances, which may promote the development of the potential meta-devices for nonlinearity, lasing action, and sensing.

12 pages,5 figures

References in corpus (5)

• Topological nature of bound states in the radiation continuum
• High-Q supercavity modes in subwavelength dielectric resonators
• Multipolar nonlinear nanophotonics
• Nonlinear optics at all-dielectric nanoantennas and metasurfaces
• Broken symmetry dielectric resonators for high quality-factor Fano metasurfaces

Cited by in corpus (5)

• Planar chiral metasurfaces with maximal tunable chiroptical response driven by bound states in the continuum
• Low-Contrast BIC Metasurfaces with Quality Factors Exceeding 100,000
• Efficient Second Harmonic Generation from Silicon Slotted Nanocubes with Bound States in the Continuum
• Cylindrical vector beams reveal radiationless anapole condition in a resonant state
• Optical bound states in the continuum in subwavelength gratings made of an epitaxial van der Waals material