Non-thermal emission in gap-mode plasmon photoluminescence

• Published in: Nature communications Vol. 15; no. 1; pp. 4468 - 8
• Main Authors: Lemasters, Robert, Manjare, Manoj, Freeman, Ryan, Wang, Feng, Pierce, Luka Guy, Hua, Gordon, Urazhdin, Sergei, Harutyunyan, Hayk
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 25.05.2024; Nature Publishing Group; Nature Portfolio
• Subjects: 639/624/399/1015; 639/925/357/354; Approximation; Conduction bands; Confinement; Controllability; Dipoles; Electron states; Emissions; Fermi-Dirac statistics; Geometry; Hot electrons; Humanities and Social Sciences; Lasers; Light; Luminescence; multidisciplinary; Nanoparticles; Nanostructure; Nanowires; Photoluminescence; Photons; Plasmonics; Resonators; Science; Science (multidisciplinary); Thermal emission; Wavelength; Wire
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-024-48928-4

Photoluminescence from spatially inhomogeneous plasmonic nanostructures exhibits fascinating wavelength-dependent nonlinear behaviors due to the intraband recombination of hot electrons excited into the conduction band of the metal. The properties of the excited carrier distribution and the role of localized plasmonic modes are subjects of debate. In this work, we use plasmonic gap-mode resonators with precise nanometer-scale confinement to show that the nonlinear photoluminescence behavior can become dominated by non-thermal contributions produced by the excited carrier population that strongly deviates from the Fermi-Dirac distribution due to the confinement-induced large-momentum free carrier absorption beyond the dipole approximation. These findings open new pathways for controllable light conversion using nonequilibrium electron states at the nanoscale. Photoluminescence from plasmonic nanostructures exhibits diverse wavelength dependent nonlinear behaviors with debated origins. Here, authors use plasmonic gap mode resonators with precise nanoscale confinement to show this nonlinear emission can become dominated by non-Fermi carrier contributions.