Multimode Lasing in Supercell Plasmonic Nanoparticle Arrays

Abstract

Multicolor light sources can be used in applications such as lighting and multiplexing signals. In photonic and plasmonic systems, one way to achieve multicolor light is via multimode lasing. To achieve this, plasmonic nanoparticle arrays are typically arranged in superlattices that lead to multiple dispersions of the single arrays coupled via the Bragg superlattice Bragg modes. Here, we show an alternative way to enable multimode lasing in plasmonic nanoparticle arrays. We design a supercell in a square lattice by leaving part of the lattice sites empty. This results in multiple dispersive branches caused by the supercell period and hence creates additional band edges that can support lasing. We experimentally demonstrate multimode lasing in such a supercell array. Furthermore, we identify the lasing modes by calculating the dispersion by combining the structure factor of the array design with an empty lattice approximation. We conclude that the lasing modes are the 74th Γ- and 106th X-point of the supercell. By tuning the square lattice period with respect to the gain emission, we can control the modes that lase. Finally, we show that the lasing modes exhibit a combination of transverse electric and transverse magnetic mode characteristics in polarization-resolved measurements.

Unidirectional Lasing from Mirror-Coupled Dielectric Lattices

“…Compact lasers are important for applications ranging from high-speed data transmission to full-color display technologies to biological sensing. − The bound states in the continuum (BICs) in periodic photonic structures have attracted significant interest as lasing modes because these modes are decoupled from the radiation continuum and can in theory support infinite quality factors ( Q factors) if without any dissipative losses. , BIC lasers have been demonstrated with compact device size, large-area single mode, vortex or chiral emission, − exciton–polariton condensation, and emission direction tuning. − On the other hand, metal nanoparticle lattices can support plasmonic surface lattice resonances (SLRs) because of the coupling between localized surface plasmon modes in individual nanoparticles and diffractive modes from the lattices. − The plasmonic SLR modes allow for strong electric field confinement in subwavelength volumes. Through the design of lattice geometry, unit cell, and refractive index environment, this plasmonic platform has enabled lasing emission with controlled polarization, color, and emission angles. − Although the lasing properties can be engineered from the above periodic lattices, most devices show bidirectional lasing emission (along the two opposite out-of-plane directions) due to the symmetry of these photonic cavities.…”