Loss-Driven Topological Transitions in Lasing

Abstract

We experimentally observe lasing in a hexamer plasmonic lattice and find that, when tuning the scale of the unit cell, the polarization properties of the emission change. By a theoretical analysis, we identify the lasing modes as quasi-bound-states in continuum of topological charges of zero, one, or two. A T-matrix simulation of the structure reveals that the mode quality (Q) factors depend on the scale of the unit cell, with highest-Q modes favored by lasing. The system thus shows a loss-driven transition between lasing in modes of trivial and high-order topological charge.

Visualization of Photonic Band Structures via Far-field Measurements in SiNx Photonic Crystal Slabs

“…Therefore, combined with the observations of the two spiral arms in equal-thickness interference and the bifurcation pattern in equal-inclination interference (See Figure S2 in Supplementary Material), the topological charge of q = +1 can be deduced through Eq. ( 1), which is consistent with the former reports [41][42][43] . Those results demonstrate that the experimental approach presented here can be employed to conveniently and effectively characterize not only the common features such as energy-momentum dispersion but also the optical singularity in photonic crystal slab, for instance, BICs, through the measurements of far-field radiation 35,41 .…”

Chiral Optical Properties of Plasmonic Kagome Lattices

“…36 Expanding or shrinking the hexamer unit cells of a hexagonal lattice has also been shown to change the topological charge of the system and introduce polarization-tunable lasing. 37 Since non-Bravais lattices facilitate additional coupling interactions that affect near-field and far-field properties, understanding how lattice geometry responds to polarization is important.…”

“…In addition, the arrangement of particles within a unit cell of non-Bravais lattices can lead to polarization-dependent properties such as chiral lattice resonances in square lattices with dimer unit cells , or the lattice Kerker effect in lattices of plasmonic trimer oligomers . Expanding or shrinking the hexamer unit cells of a hexagonal lattice has also been shown to change the topological charge of the system and introduce polarization-tunable lasing . Since non-Bravais lattices facilitate additional coupling interactions that affect near-field and far-field properties, understanding how lattice geometry responds to polarization is important.…”

Multimode Lasing in Supercell Plasmonic Nanoparticle Arrays

“…The spectral position of the SLRs can be easily tailored by varying the lattice geometry and period while simultaneously yielding high quality (Q-) factors. − Combined with emitters such as organic dye molecules, plasmonic nanoparticle arrays are an effective system to study light–matter interactions such as strong coupling or Bose–Einstein condensation. − Lasing in plasmonic nanoparticle arrays has been studied in various lattice geometries such as square, rectangular, honeycomb, or hexagonal lattices. Typically, the systems produce lasing at a band edge originating at high symmetry points of the lattice, for instance, at the Γ-, K -, or M -points. − Also, bound states in continuum which have extraordinary high Q-factors have been recently exploited for lasing in plasmonic arrays. − …”