Hot carrier-mediated avalanche multiphoton photoluminescence from coupled Au–Al nanoantennas

Abstract

Avalanche multiphoton photoluminescence (AMPL) is observed from coupled Au–Al nanoantennas under intense laser pumping, which shows more than one order of magnitude emission intensity enhancement and distinct spectral features compared with ordinary metallic photoluminescence. The experiments are conducted by altering the incident laser intensity and polarization using a home-built scanning confocal optical microscope. The results show that AMPL originates from the recombination of avalanche hot carriers that are seeded by multiphoton ionization. Notably, at the excitation stage, multiphoton ionization is shown to be assisted by the local electromagnetic field enhancement produced by coupled plasmonic modes. At the emission step, the giant AMPL intensity can be evaluated as a function of the local field environment and the thermal factor for hot carriers, in accordance with a linear relationship between the power law exponent coefficient and the emitted photon energy. The dramatic change in the spectral profile is explained by spectral linewidth broadening mechanisms. This study offers nanospectroscopic evidence of both the potential optical damages for plasmonic nanostructures and the underlying physical nature of light–matter interactions under a strong laser field; it illustrates the significance of the emerging topics of plasmonic-enhanced spectroscopy and laser-induced breakdown spectroscopy.

‘Plug-and-play’ plasmonic metafibers for ultrafast fibre lasers

“…1(b5) shows a typical metasurface made of a nanorod array fabricated on an SMFJ endface using this technique (see 'Nanofabrication of the metafiber using EBL' in Supplementary Information for details). The advantages of such methods include low cost and high immunity to complicated plasmonic systems, such as heterodimers [9,34,35].…”

“…6(d), the surface plasmons provide a dramatic local field enhancement for the electric field E, especially when their resonances match the fundamental or high-order harmonic excitation frequencies [9,65,66]. Furthermore , the surface components of nonlinear susceptibilities, for example, 𝜒 (3) 𝑠𝑢𝑟 𝑓 in the process of two-photon absorption, will be significantly altered owing to the hot carrier redistributions during strong light-matter interactions [35,45,46,67]. Given the above two contributions, an extra hot carrier (mainly from electrons)-induced nonlinearity is produced and shifts the absorption resonances [67].…”

Hot Carrier-Induced Nonlinear Photoluminescence in a Thin Indium Tin Oxide Layer Patterned by Ga Ion Beam Milling

“…Alternative mechanisms have recently been proposed to account for the up-converted broadband emission. They share one common feature, which is the generation of an out-of-equilibrium electron gas swiftly produced after the absorption of the laser pulse. − In this framework, Lupton and co-workers have shown that the nonlinear exponent stems from an absorption process only at a low laser intensity. At large power densities, the nonlinearity is better described as arising from a radiating bath of electrons warmed to very high temperatures .…”

Demonstration of a Plasmonic Nonlinear Pseudodiode

“…A major advantage of this two-dimensional design is that such a material asymmetry is relatively easy to implement using standard nanofabrication techniques: e.g., single-exposure electron-beam lithography (EBL) . Furthermore, the combination of plasmonic metals is known to enhance nonlinear processes. , To the best of our knowledge, this is the first experimental demonstration of a plasmonic metasurface for asymmetric SHG, although we note that in a recent experimental demonstration Kruk et al utilized a combination of dielectric nonlinear materials for third-harmonic generation . Additionally, we perform a homogenization analysis of the metasurface to extract effective susceptibilities and reveal the bianiostropic property of our metasurface.…”