Carrier recombination and plasmonic emission channels in metallic photoluminescence

Abstract

We systematically investigate the metallic photoluminescence (MPL) emitted from plasmonic nanoparticles (NPs) upon excitation with ultrafast laser pulses using a scanning confocal optical microscope (SCOM). By comparing the emission spectra of Au NPs of varying dimensions with the corresponding dark-field scattering spectra, indications are found that MPL encompasses two emission channels: the particle plasmons (PPs) and the electron-hole (e-h) pair recombination. The plasmons can be interpreted to play a twofold role: in the excitation process they provide the local field enhancement, and in the emission process they offer extra radiation channels.

Saturable plasmonic metasurfaces for laser mode locking

“…For 20 years, the nonlinear absorption of plasmonic devices has also attracted much interest as it leads to a complex cascade of electronic processes involving hot electrons, which are of particular interest for many applications [20][21][22] ranging from photochemistry to ultrafast photodetectors 23,24 . Indeed, the nonlinear absorption of gold plasmonic devices leads to the excitation of a hotelectron cloud relaxing at a sub-picosecond timescale, which can be used to seed another physical or chemical process [25][26][27][28] . In this ultrafast electronic excitation regime, the reduction in the occupation of the electronic states well below the gold Fermi level when the electron distribution becomes athermal leads to transient absorption related to a change in the metal dielectric function 25,29 .…”

Strong second-harmonic generation from Au–Al heterodimers

“…Nonlinear optics was established shortly after the construction of the first laser system. 1 Nonlinear optical processes such as frequency-mixing, 2 optical Kerr effect, 3 optical phase conju-gation, 4 four-wave mixing, 5 Raman amplification, 6 stimulated Brillouin scattering, 7 multi-photon absorption 8,9 and multiple photoionization 10 were systemically investigated in the last several decades. Their advanced applications range from optical fibers, 11 optical switches, 12 photonic crystals 13 and other optical devices to modern nanostructures.…”

“…8 LSPRs have indeed attracted particular attention as they allow enhancing and concentrating electromagnetic fields in sub-wavelength volumes. 14,15 Their influences on the nonlinear optical properties of plasmonic nanoantennas such as SHG, 8,[16][17][18][19][20] twophoton photoluminescence (TPL), 9,21,22 third and higher harmonics generation, 23 as well as multi-photon photoluminescence 9 have been thoroughly investigated. Nonlinear plasmonics, as a new branch of nano optics, has emerged recently.…”

“…35 Specifically, SHG from single Au disc monomers, Al disc monomers and Au-Al disc heterodimers with nanogaps is systematically investigated using a home-built scanning confocal nonlinear optical microscope, which is illustrated in the ESI. † 8,9,21,36 Spectrally integrated SHG intensities and the linear optical responses are recorded and compared experimentally. The corresponding theoretical simulations are performed with the assistance of a surface integral equation (SIE) method.…”

Nonlinear plasmonic behavior of nanohole arrays in thin gold films for imaging lipids

“…27 Previously, the TPEL properties of Au nanorods, discs, and connected dimers have been studied, showing that the TPEL intensities are dominated by localized surface plasmon resonance (LSPR) wavelengths. [28][29][30] The nanohole array with a 400 nm periodicity shows transmission maxima of the localized surface plasmon peaks (1,1) and (1,0) at around 610 nm and 780 nm, respectively [cf. Fig.…”