Efficient Thermo-Optic Switching and Modulating in Nonlocal Metasurfaces.

High- optical resonances in nonlocal metasurfaces, benefiting from significantly enhanced light/matter interactions, feature strong responses even under a weak external stimulus. In this work, we leverage the high- resonances of quasi-guided modes (QGMs) supported by a photonic crystal slab (PCS) structure to achieve efficient optical switching/modulation. The QGMs with an experimentally measured -factor of ∼2200 are realized by shifting every second column of air holes in a rectangular lattice within a silicon slab.

The Strong Coupling Effect between Metallic Split-Ring Resonators and Molecular Vibrations in Polymethyl Methacrylate.

We propose and study a nanoscale strong coupling effect between metamaterials and polymer molecular vibrations using metallic split-ring resonators (SRRs). Specifically, we first provided a numerical investigation of the SRR design, which was followed by an experimental demonstration of strong coupling between mid-infrared magnetic dipole resonance supported by the SRRs fabricated on a calcium fluoride substrate and polymethyl methacrylate molecular vibrations at 1730 cm. Characterized by the anti-crossing feature and spectral splitting behaviors in the transmission spectra, these results demonstrate efficient nanoscale manipulation of light-matter interactions between phonon vibrations and metamaterials.

Efficient and Shape-Sensitive Manipulation of Nanoparticles by Quasi-Bound States in the Continuum Modes in All-Dielectric Metasurfaces.

Current optical tweezering techniques are actively employed in the manipulation of nanoparticles, e.g., biomedical cells.

High-Q optical resonances with robustness based on the quasi-guided modes in waveguide moiré gratings.

High-Q resonances, especially those with high spectral tunability and large robustness of the Q factors, are always sought in photonic research for enhanced light-matter interactions. In this work, by rotating the 1D ridge grating on a slab waveguide in both the clockwise and counterclockwise directions by a certain angle θ, we show that the original subwavelength lattice can be converted into waveguide moiré gratings (WMGs), with the period increased to a larger value determined by the value of θ. These period-increasing perturbations will cause the First Brillouin Zone (FBZ) of the 1D grating to shrink, and thus convert the non-radiating guided modes with the dispersion band below the light line into quasi-guided modes (QGMs) above the light line, which can be accessed by free space radiations.

Narrowband mid-infrared thermal emitters based on the Fabry-Perot type of bound states in the continuum.

The development of narrow-band thermal emitters operating at mid-infrared (MIR) wavelengths is vital in numerous research fields. However, the previously reported results obtained with metallic metamaterials were not successful in achieving narrow bandwidths in the MIR region, which suggests low temporal coherence of the obtained thermal emissions. In this work, we demonstrate a new design strategy to realize this target by employing the bound state in the continuum (BIC) modes of the Fabry-Perot (FP) type.