Chains of nanoparticles for flat-band emission and lasing

TL;DR

This paper introduces nanoparticle chain lattices that support flat bands enabling lasing and tailored light emission, advancing the design of narrowband, polarized light sources.

Contribution

It presents a new nanoparticle chain lattice design supporting flat bands and demonstrates lasing and emission control in these structures.

Findings

Lasing observed in the TM mode of single nanoparticle chains.

Transition from flat band lasing to normal-incidence lasing with increasing chains.

Partially coherent emission from 2D chain lattices depending on pump power and polarization.

Abstract

Controlling light-matter interactions is central to photonic technologies ranging from lasers to optical information processing. Suitably designed photonic structures give rise to flat (dispersionless) bands, where the density of states diverges, and group velocity goes to zero, allowing light localization. These properties make flat bands attractive for lasing; however, designing photonic structures supporting flat bands suitable for lasing is challenging. Here, we introduce nanoparticle chain lattices. These chain geometries provide long-range coupled systems that support, at predictable wavelengths, bands that are totally flat and extend over the full angular range. We demonstrate lasing in the transverse-magnetic (TM) mode of single chains of nanoparticles and explain the transition from flat band lasing to the single-mode normal-incidence (Gamma-point) lasing as the number of chains is increased. Moreover, we show partially coherent emission from square and triangular two-dimensional chain lattices. The excited modes depend on the pump power and polarization. Our results establish chain lattices as a versatile platform for exploring flat band lasing and suggest new routes toward narrowband, linearly polarized, and bright light sources with tailored coherence.