Hybridization of floor lattice resonances induces dual-band sure states in continuum

Hybridization of surface lattice resonances induces dual-band bound states in continuum
Proposed dual-band BICs in silicon bipartite nanodisk array. (A) 3D- and (B) top-viewed schematics of the silicon bipartite nanodisk array beneath examine, which could be handled because the hybridization of two single-nanodisk arrays (in pink and blue). The unit cell with sq. lattice of interval Λ is illustrated by the pink dashed field containing two silicon nanodisks with diameter d and thickness h. The central nanodisk is displaced vertically from the origin of the unit cell with Δ y. (C) and (D) Simulated zeroth-order transmittance spectra (C) as features of Δy or (D) for Δy = 50 nm, exhibiting two branches of extraordinarily slim dips. The dashed line signifies the (0, ±1) or (±1, 0) RA wavelength. (E) and (F) Close to-field electrical filed distributions (colour for depth and arrows for instructions) within the x − y aircraft on the half peak of silicon nanodisk for the resonance wavelengths of quasi-BIC I and II, as indicated by the dips in (D). Symbols “+” and “−” in (E) point out cost distributions. The silicon nanodisks are outlined by white circles and a unit cell is printed by the dashed field in (E) and (F). Credit score: Nanophotonics (2022). DOI: 10.1515/nanoph-2022-0427

In metasurfaces, floor lattice resonances (SLRs) and sure state within the continuum (BIC) are two handy approaches for attaining prime quality elements (Q-factors).

A analysis group led by Dr. Li Guangyuan from the Shenzhen Institute of Superior Know-how (SIAT) of the Chinese language Academy of Sciences has revealed that hybridization of SLRs can lead to dual-band BICs in silicon metasurfaces. The measured Q-factors can attain as excessive as 1240.

Additionally they confirmed that the resonance wavelengths and Q-factors of the dual-band quasi-BICs could be conveniently tuned by various the nanoparticle dimension or the lattice interval.

This examine was revealed in Nanophotonics on Nov. 1.

Thus far, most symmetry-protected BICs in periodic nanostructures depend on the structural symmetry breaking of the unit-cell nanoparticles. Reported approaches embrace asymmetrically-shaped nanoparticles, and bipartite nanoparticles with totally different sizes. As a way to obtain excessive Q-factors for quasi-BICs, the structural asymmetry parameter ought to be tiny sufficient, posing challenges on the nanofabrication.

Measurement distinction lower than 10% may be very difficult, particularly when the nanoparticle diameter is only some hundred of nanometers. Nevertheless, the relative positions of nanoparticles could be precisely managed within the top-down nanofabrication. “This motivated us to suggest periodic bipartite nanoparticles with the central one barely shifted from the middle of the unit cell,” stated Dr. Li.

“To our shock, the electrical dipole SLRs (ED-SLRs) supported by two particular person silicon lattices are completely canceled with one another within the bipartite arrays,” stated Dr. Li. “As an alternative, we noticed dual-band BICs because of the hybridizations of two in-plane electrical quadrupole SLRs (EQ-SLRs) and of two out-of-plane magnetic dipole SLRs (MD-SLRs) which might be supported by the 2 particular person silicon lattices.”

The researchers additionally mentioned the tunability and the potential functions. They discovered that the tunability of SLRs by various the silicon nanodisks’ diameter and the lattice interval is inherited by the dual-band BICs.

“We hope this idea will assist to suppress the inherent losses and to attain excessive Q-factors for plasmonic metasurfaces,” stated Dr. Li.

Extra data:
Xiang Du et al, Twin-band sure states within the continuum based mostly on hybridization of floor lattice resonances, Nanophotonics (2022). DOI: 10.1515/nanoph-2022-0427

Hybridization of floor lattice resonances induces dual-band sure states in continuum (2022, November 14)
retrieved 14 November 2022

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