Ultralow-threshold, continuous-wave upconverting lasing from subwavelength plasmons

Abstract

Miniaturized lasers are an emerging platform for generating coherent light for quantum photonics, in-vivo cellular imaging, solidstate lighting, and fast 3D sensing in smartphones 1-3. Continuouswave (CW) lasing at room temperature is critical for integration with opto-electronic devices and optimal modulation of optical interactions 4,5. Plasmonic nanocavities integrated with gain can generate coherent light at sub-wavelength scales 6-9 , beyond the diffraction limit that constrains mode volumes in dielectric cavities such as semiconducting nanowires 10,11. However, insufficient gain 1 with respect to losses and thermal instabilities in nanocavities has limited all nanoscale lasers to pulsed pump sources and/or lowtemperature operation 6-9,12-15. Here we show CW upconverting lasing at room temperature with record-low thresholds and high photostability from sub-wavelength plasmons. We achieve selective, single-mode lasing from Yb 3+ /Er 3+-co-doped upconverting nanoparticles (UCNPs) conformally coated on Ag nanopillar arrays that support a single, sharp lattice plasmon cavity mode and < /20 field confinement in the vertical dimension. The intense electromagnetic near-fields localized in the vicinity of the nanopillars result in a threshold of 70 W/cm 2 , orders of magnitude lower than other small lasers. Our plasmon-nanoarray upconverting lasers provide directional, ultra-stable output at visible frequencies under near-infrared pumping, even after six hours of constant operation, which offers prospects in previously unrealizable applications of coherent nanoscale light. Lanthanide-based UCNPs are photostable solid-state nonlinear emitters that are efficient at sequentially absorbing multiple near-infrared (NIR) photons and emitting at visible and shorter-NIR wavelengths 16-19. Recently, UCNPs have been used as gain media in small lasers, and their integration with dielectric microcavities and hyperbolic metamaterials has resulted in multi-wavelength upconverted lasing 20-22. UCNPs also exhibit long radiative lifetimes (typically 100s of µs) compared to other gain materials 18,23,24 , which

Ten years of spasers and plasmonic nanolasers

“…These results clarified the long-standing debate over the viability of plasmonics in laser technology and identified situations in which plasmonic lasers have clear practical advantages. Most recently, an experiment suggested that the threshold of a plasmonic laser can be lowered to 70 W cm −2 via a combination of a lattice plasmonic cavity and an upconverting nanoparticle gain material 121 .…”

Lanthanide‐Based Luminescent Materials for Waveguide and Lasing

“…The low thresholds of thesem icrolasers were ascribed to the avalanche-like upconversion mechanism,a long with the spatialo verlap of the upconversionn anocrystals with the WGM microcavity.T hey also demonstrated CW singlemode upconverting lasing at room temperature from NaYF 4 :Yb/Er@NaYF 4 nanocrystals conformally coated on Ag nanopillar arrays, which support as ingle, sharp lattice plasmonic cavity mode ( Figure 10 j-n). [45] These plasmon-nanoarray upconverting lasers exhibit at hreshold orders of magnitude lower than other miniaturized lasers due to intense electromagnetic near-fields localized in the vicinity of the nanopillars.…”

Diffractive dipolar coupling in non-Bravais plasmonic lattices

“…28,31 So far, the great majority of the studies have focused on simple geometries, typically realized by Bravais lattices. Despite this, extremely rich physics and unexpected phenomena, such as plasmon [32][33][34] and polariton lasing, 35,36 strong light-matter coupling [37][38][39][40] and quantum phase transitions, [41][42][43] have emerged, making this research area vibrant and fast-growing.…”