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Merging mirror-coupled bound states in the continuum at THz frequency
Optics Letters
|August 29, 2025
Summary
Researchers developed merging mirror-coupled bound states in the continuum (BICs) for THz frequencies. These BICs offer higher Q-factors and field enhancement, enabling advanced all-optical devices.
Area of Science:
- Optics and Photonics
- Metamaterials Science
Background:
- Bound states in the continuum (BICs) are fundamental wave phenomena with potential in various optical applications.
- Conventional mirror-coupled BICs offer unique properties but can be sensitive to structural imperfections.
Purpose of the Study:
- To achieve and characterize merging mirror-coupled BICs at THz frequencies in a novel metasurface.
- To investigate the enhanced properties and robustness of these merging BICs compared to conventional ones.
- To demonstrate the potential of merging BICs for advanced all-optical functionalities.
Main Methods:
- Fabrication of a metasurface comprising silicon (Si) block arrays on a gold (Au) mirror with a silicon dioxide (SiO2) spacer.
- Theoretical and experimental analysis of the optical properties of the metasurface at THz frequencies.
- Investigation of nonlinear optical phenomena, including third-harmonic generation and optical bistability.
Main Results:
- Successful achievement of merging mirror-coupled BICs at THz frequencies.
- Demonstrated higher Q-factors and local field enhancement for merging BICs compared to conventional mirror-coupled BICs at the same in-plane wavevector.
- Confirmed robustness of merging BICs to nanostructure imperfections.
- Observed efficient third-harmonic generation and low-threshold optical bistability.
Conclusions:
- Merging mirror-coupled BICs present a promising platform for enhancing light-matter interactions in metasurfaces.
- These BICs combine the benefits of mirror-coupled BICs and merging BICs, offering superior performance and robustness.
- The demonstrated functionalities pave the way for the development of next-generation all-optical devices.
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