Effect of plasmonic mode on plasmon-based lasers

Abstract

For the last few years, plasmon-based lasers have been investigated theoretically and experimentally. Several configurations have been reported. They are composed of quantum emitters coupled to a plasmonic structure. In this paper, we investigate the effect of the plasmon mode on the far-field and near-field characteristics of a nanolaser composed by a periodic array of metallic nanoparticles covered by gain materials under optical pumping. Two configurations were investigated. The first structure supported a localized surface plasmon (LSP) mode, while the second a surface lattice plasmon (SLP) mode. This theoretical work relies on semi-quantum calculations based on a four-level gain molecule and a time-domain approach. We demonstrated that lasing in a SLP mode requires a lower concentration of quantum emitters and generates a higher far-field emission with a lower threshold than lasing in a LSP mode. At nanoscale, near-field enhancement at the emission wavelength and above the threshold is 2 orders of magnitude higher with the SLP than the LSP mode. Our results with a general character show that designing a plasmon-based laser that sustains the SLP mode will result in a better lasing efficiency than with a LSP mode.