Advances in ultrafast plasmonics

Abstract

In the past 20 years, we have reached a broad understanding of many light-driven phenomena in nanoscale systems. The temporal dynamics of the excited states are instead quite challenging to explore, and, at the same time, crucial to study for understanding the origin of fundamental physical and chemical processes. In this review, we examine the current state and prospects of ultrafast phenomena driven by plasmons both from a fundamental and applied point of view. This research area is referred to as ultrafast plasmonics and represents an outstanding playground to tailor and control fast optical and electronic processes at the nanoscale, such as ultrafast optical switching, single photon emission, and strong coupling interactions to tailor photochemical reactions. Here, we provide an overview of the field and describe the methodologies to monitor and control nanoscale phenomena with plasmons at ultrafast timescales in terms of both modeling and experimental characterization. Various directions are showcased, among others recent advances in ultrafast plasmon-driven chemistry and multi-functional plasmonics, in which charge, spin, and lattice degrees of freedom are exploited to provide active control of the optical and electronic properties of nanoscale materials. As the focus shifts to the development of practical devices, such as all-optical transistors, we also emphasize new materials and applications in ultrafast plasmonics and highlight recent development in the relativistic realm. The latter is a promising research field with potential applications in fusion research or particle and light sources providing properties such as attosecond duration.

Can 2D Semiconductors Be Game-Changers for Nanoelectronics and Photonics?

“…Moreover, 2D semiconductors exhibit fast response times in the femtosecond to picosecond range, rendering them suitable for broadband ultrafast NLOs. 259 Table 1 provides key figure-of-merit comparisons of NLO characteristics between 2D semiconductors and conventional nonlinear bulk crystals. TMD monolayers are the most studied 2D semiconductor systems with NLO properties in saturation absorbers (SA), second harmonic generation (SHG), sum and difference frequency generation (SFG), third and fourth harmonic generation (THG and FHG), optical limiting, full wave mixing (FWM), two photon absorption (TPA), and so on.…”

“…Furthermore, their subnanometer thickness reduces the technical necessity for precise phase matching between the excited and emitted light. Moreover, 2D semiconductors exhibit fast response times in the femtosecond to picosecond range, rendering them suitable for broadband ultrafast NLOs Table provides key figure-of-merit comparisons of NLO characteristics between 2D semiconductors and conventional nonlinear bulk crystals.…”

Peeking into the Femtosecond Hot-Carrier Dynamics Reveals Unexpected Mechanisms in Plasmonic Photocatalysis

“…Light is well-known to be an eclectic reagent, catalyst, and possible product in chemical reactions. − Its interaction with nanostructures has further expanded the possibility of using light to manipulate chemical systems with extremely high precision and accuracy and, in turn, could affect many relevant technological fields such as sensing, catalysis, renewable energy, communication, and medicine. − Among all possible processes appearing at these scales, the activation of the Localized Surface Plasmon Resonances (LSPR) is one of the most peculiar and in the past decades its theoretical comprehension already gave notable outcomes. ,− A particularly interesting and technologically relevant feature arising from the activation of the LSPR resides in the use of the energy released by its decay with a host of potential applications. − LSPR decay can be summarized through the following stages: following its excitation, the collective oscillation of the electronic cloud starts to dephase (Landau damping), resulting in the formation of electron–hole pairs, neutral excitations that store the energy originally absorbed by the plasmon. Such nonequilibrium state of excited electrons and holes rapidly thermalizes, resulting in a configuration where the carriers (electrons and holes) follow a Fermi–Dirac distribution at a higher temperature with respect to the lattice one, as if the electronic system was heated up.…”

Quantitative Ultrafast Magnetoacoustics at Magnetic Metasurfaces

“…The parametric effect represents a new way to quantify strain amplitudes, which is otherwise possible only in sophisticated time-resolved X-ray diffraction experiments . Moreover, parametric excitation opens the door to the generation of magnetization precession with extremely large amplitude, which is required for magnetoelastic switching in magnetostrictive nanomagnets , or ultrafast control of magnetoplasmonic nanostructures. , …”

“…1 Moreover, parametric excitation opens the door to the generation of magnetization precession with extremely large amplitude, which is required for magnetoelastic switching in magnetostrictive nanomagnets 5,18 or ultrafast control of magnetoplasmonic nanostructures. 19, 20 An elastic half-space or a substrate, which is thick compared to the acoustic wavelength, supports several basic surface modes. Rayleigh SAW acoustic eigenmodes propagate along the surface and are attenuated by intrinsic damping due to the phonon−phonon interactions in both dielectric and semiconductor substrates.…”