Bound states in the continuum (BICs) are widely studied for their ability to confine light, produce sharp resonances for sensing applications and serve as avenues for lasing action with topological characteristics. Primarily, the formation of BICs in periodic photonic band gap structures are driven by symmetry incompatibility; structural manipulation or variation of incidence angle from incoming light. In this work, we report two modalities for driving the formation of BICs in terahertz metasurfaces. At normal incidence, we experimentally confirm polarization driven symmetry-protected BICs by the variation of the linear polarization state of light. In addition, we demonstrate through strong coupling of two radiative modes the formation of capacitively-driven Freidrich-Wintgen BICs, exotic modes which occur in off-
Properties of photonic devices fashioned with dual‐grating metamaterials are reported. Enclosed by dual periodic regions, laterally propagating Bloch modes undergo radiative scattering and leaky‐mode resonance whose properties differ markedly from those with single periodicity. The resonance signatures are sensitively controlled by the relative parameters of the periodic regions. In particular, if they are physically identical and separated by a half‐wavelength, there ensues a bound state in the continuum (BIC) with extremely narrow resonance linewidth. On varying the separation between the periodic layers, the linewidth and corresponding
- Award ID(s):
- 1809143
- NSF-PAR ID:
- 10445900
- Publisher / Repository:
- Wiley Blackwell (John Wiley & Sons)
- Date Published:
- Journal Name:
- Advanced Optical Materials
- Volume:
- 7
- Issue:
- 20
- ISSN:
- 2195-1071
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Γ points not accessible by symmetry-protected BICs. The capacitance-mediated strong coupling at 0° polarization is verified to have a normalized coupling strength ratio of 4.17% obtained by the Jaynes-Cummings model. Furthermore, when the polarization angle is varied from 0° to 90° (0° ≤ϕ < 90°), the Freidrich-Wintgen BIC is modulated until it is completely switched off at 90°. -
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