Incandescence‐Like Nonlinear Ultra‐Broadband Emission from Randomly Assembled Plasmonic Nanoparticles

Abstract

AbstractEfficient light sources with emission spanning from visible to infrared range are of central importance for applications including precision spectroscopy and sensing. Under irradiation with constant‐wave (CW) lasers, here, the generation and modulation of incandescence‐like ultra‐broad emission (600–4000 nm) from random aggregates of metal oxide nanoparticles are demonstrated by judicious doping of free carriers, that of any existing photoluminescence process and commercial broadband light sources. It is revealed that this emission is associated with a dominant thermal origin and it is characterized by a pump‐dependent nonlinear response with the maximum order of nonlinearity exceeding 8, which is benefited from the intensified light‐matter interaction mediated by the high density of hot spots in the random plasmonic nanostructures. Moreover, by leveraging the prominent plasmon response, the emission spectra and intensity can be tuned by the Drude terms of the oxide nanoparticles. the use of this broadband infrared (IR) emission is exploited further as the light source for the demonstration of IR spectrometry, exemplified by the examination of organic molecules. The method for producing strong and continuum IR emission based on engineered plasmonic oxide can stimulate further exploitation of miniaturized IR light sources for applications including imaging and sensing.