M-Point Lasing in Hexagonal and Honeycomb Plasmonic Lattices

Abstract

This paper reports the observation of band-edge states at the high-symmetry M-point in the first Brillouin zone of hexagonal and honeycomb plasmonic nanoparticle (NP) lattices. The surface lattice resonance at the M-point (SLR M ) of a hexagonal lattice results from asymmetric out-of-plane dipole coupling between NPs. In contrast to the hexagonal lattice, honeycomb lattices support two SLR modes at the M-point because of their non-Bravais nature: (1) a blue-shifted SLR M1 from the coupling of two distinct out-of-plane dipole LSP resonances, and (2) a redshifted SLR M2 from in-plane dipole−dipole coupling. By incorporating organic dye solutions as gain media with Ag NP lattices, we achieved M-point lasing from both hexagonal and honeycomb lattices. Understanding coupling mechanisms at high-symmetry points in NP lattices with the same geometry but different unit cells is important to assess the prospects of topological states in plasmonic systems.

Light–Matter Interactions in Hybrid Material Metasurfaces

“…136 In addition, M-point lasing from both hexagonal and honeycomb lattices has been reported with emission angles near 60°. 137 SLR modes that support in-plane light scattering can facilitate tunability at other lasing emission angles. 138 The 3D light cone boundary, which describes the free photon dispersion in the 2D E−k || relation, corresponds to light propagation along the in-plane direction (θ = 90°).…”

“…High-symmetry points of plasmonic metasurfaces at nonzero wavevectors can be also used to manipulate lasing emission angles. − In contrast to surface-normal lasing from the Γ point, the K-points of a honeycomb plasmonic lattice can enable six lasing beams at ∼35° along the Γ–K lattice directions (Figure c) . In addition, M-point lasing from both hexagonal and honeycomb lattices has been reported with emission angles near 60° . SLR modes that support in-plane light scattering can facilitate tunability at other lasing emission angles .…”

Polarized coherent emission outside high-symmetry points of dye-coupled plasmonic lattices

“…[14][15][16][17][18][19][20][21] While in the vast majority of the works plasmonic nanoarrays with Bravais squared or rectangular lattices are used as feedback cavities, very recently a great interest arose for studying the extremely rich features of hexagonal arrays. [22][23][24][25][26] A relatively simple and cost-effective method to produce hexagonal or honeycomb ordered arrays of nanostructures is by nanosphere lithography (NSL). 27 NSL is a scalable, high-throughput technique and it can be employed to realize different typologies of two-dimensional plasmonic nanoarrays with proper optical functionalities for different applications, as biosensing, 28 third-a University of Padova, Department of Physics and Astronomy, NanoStructures Group, via Marzolo 8, I-35131 Padova, Italy.…”

Quasi-Random Multimetallic Nanoparticle Arrays

“…The nanostructuring of materials has resulted in structural color in plants and animals , and their artificial analogs − as well as state-of-the-art solar cells and light-driven microdrones . Periodic arrays of metallic nanoparticles (NPs) can support surface lattice resonances (SLRs), − hybrid plasmonic-photonic modes of increased interest in sensing, , and light–matter interactions including lasing − and strong coupling. − Most work has focused on SLRs formed from the coupling between localized surface plasmons (LSPs) of the NPs and the first-order diffraction modes of an array at the high-symmetry points in reciprocal space (e.g., Γ-point, M-point, K-point). , Although particle dimension, shape, and material as well as lattice spacing, orientation and symmetry can be tuned to achieve high-quality SLRs over a broad range of wavelengths, −,, the diffraction orders of an array with fixed periodicity constrain SLR excitation to narrow spectral windows.…”

“…Another approach to create multimode SLR substrates is by changing the array geometry. For example, rhombohedral and honeycomb arrays ,, have first- and second-order diffractive modes at different wavelengths that can couple to the same broad LSP to form two SLR modes. Tuning the array geometry to couple to a single LSP mode will also have similar issues in generating SLR modes with uniformly high quality.…”