Recent investigations on optical nonlinearities of plasmonic materials suggest their responses may be even beyond the usual perturbative description. To better understand these surprisingly strong responses, we develop here a simple but general approach to describe the nonlinear optical response of plasmonic materials up to $n$th perturbation order. We apply the approach to understand spectral broadening occurring in resonant metasurfaces and investigate the enhancement of high-harmonic generation from multiply-resonant metasurfaces, predicting an over million-fold enhancement of higher harmonics.
We propose a new concept for generation of ultrashort pulses based on transient plasmonic resonance in nanoparticle composites. Photoionization and free-carriers plasma change the susceptibility of nanoparticles on a few-femtosecond scale. This results in a narrow time window during the pump pulse duration when the system is in plasmonic resonance, accompanied by a short burst of the local field. During this process, frequency-tunable few-fs pulses are generated. We elucidate the details of the above mechanism, and investigate the influences of different contributing processes.
We study how the collective effects of nanoparticles arranged in rectangular arrays influence their temporal plasmon response and field enhancement property. By systematically changing the lattice constant for arrays containing identical metal nanorods, we experimentally demonstrate how grating induced effects affect the position and, more importantly, the broadening of extinction spectra. We correlate these effects with the achievable field enhancement and the temporal duration of plasmon transients and formulate criteria for the generation of enhanced few-cycle localized plasmon oscillations…
Ultrafast nanophotonics is an emerging research field aimed at the development of nanodevices capable of light modulation with unprecedented speed. A promising approach exploits the optical nonlinearity of nanostructured materials (either metallic or dielectric) to modulate their effective permittivity via interaction with intense ultrashort laser pulses. While the ultrafast temporal dynamics of such nanostructures following photoexcitation has been studied in depth, sub-ps transient spatial inhomogeneities taking place at the nanoscale have been so far almost ignored. Here we theoretically pr…
Nanoscale membrane assemblies of sphingolipids, cholesterol, and certain proteins, also known as lipid rafts, play a crucial role in facilitating a broad range of important cell functions. Whereas on living cell membranes lipid rafts have been postulated to have nanoscopic dimensions and to be highly transient, the existence of a similar type of dynamic nanodomains in multicomponent lipid bilayers has been questioned. Here, we perform fluorescence correlation spectroscopy on planar plasmonic antenna arrays with different nanogap sizes to assess the dynamic nanoscale organization of mimetic bio…
Optical response of free-electron gas leads to inherent nonlinear optical behaviour of nanostructured plasmonic materials enabled via both strong local field enhancements and inherent complex electron dynamics. We present a comprehensive treatment of microscopic polarization of conduction electrons in the time-domain using full hydrodynamic description which allows self-consistent modelling of linear and nonlinear response and multiple harmonics generation. The effects of convective acceleration, magnetic contribution of the Lorenz force, quantum electron pressure, and nanostructures boundarie…
We propose an experimental arrangement to image, with attosecond resolution, transient surface plasmonic excitations. The required modifications to state-of-the-art setups used for attosecond streaking experiments from solid surfaces only involve available technology. Buildup and life times of surface plasmon polaritons can be extracted and local modulations of the exciting optical pulse can be diagnosed {\it in situ}.
Dissipation of electromagnetic energy through absorption is a fundamental process that underpins phenomena ranging from photovoltaics to photography, analytical spectroscopy, photosynthesis, and human vision. Absorption is also a dynamic process that depends on the duration of the optical illumination. Here we report on the resonant plasmonic absorption of a nanostructured metamaterial and the non-resonant absorption of an unstructured gold film at different optical pulse durations. By examining the absorption in travelling and standing waves, we observe a plasmonic relaxation time of 11 fs as…
Donut-shaped laser radiation, carrying orbital angular momentum, namely optical vortex, recently was shown to provide vectorial mass transfer, twisting transiently molten material and producing chiral micro-scale structures on surfaces of different bulk materials upon their resolidification. In this paper, we show for the first time that nanosecond laser vortices can produce chiral nanoneedles (nanojets) of variable size on thin films of such plasmonic materials, as silver and gold films, covering thermally insulating substrates. Main geometric parameters of the produced chiral nanojets, such …
Intense multi-THz pulses are used to study the coherent nonlinear response of bulk InSb by means of field-resolved four-wave mixing spectroscopy. At amplitudes above 5 MV/cm the signals show a clear temporal substructure which is unexpected in perturbative nonlinear optics. Simulations based on a two-level quantum system demonstrate that in spite of the strongly off-resonant character of the excitation the high-field pulses drive the interband resonances into a non-perturbative regime of Rabi flopping.
Excitation of coherent optical phonons in solids provides a pathway for ultrafast modulation of light on a sub-ps timescale. Here, we report on efficient 3.6 THz modulation of light reflected from hybrid metal/semiconductor plasmonic crystals caused by lattice vibrations in a few nm thick layer of elemental tellurium. We observe that surface plasmon polaritons contribute significantly to photoinduced formation of this thin layer at the interface between a telluride-based II-VI semiconductor, such as (Cd,Mg)Te or (Cd,Mn)Te, and a one-dimensional gold grating. The change in interface composition…
We review the recent progress in experimental and theoretical research of interactions between the acoustic, magnetic and plasmonic transients in hybrid metal-ferromagnet multilayer structures excited by ultrashort laser pulses. The main focus is on understanding the nonlinear aspects of the acoustic dynamics in materials as well as the peculiarities in the nonlinear optical and magneto-optical response. For example, the nonlinear optical detection is illustrated in details by probing the static magneto-optical second harmonic generation in gold-cobalt-silver trilayer structures in Kretschmann…
Ultrafast laser measurements probe the non-equilibrium dynamics of excited electrons in metals with increasing temporal resolution. Electronic structure calculations can provide a detailed microscopic understanding of hot electron dynamics, but a parameter-free description of pump-probe measurements has not yet been possible, despite intensive research, because of the phenomenological treatment of electron-phonon interactions. We present ab initio predictions of the electron-temperature dependent heat capacities and electron-phonon coupling coefficients of plasmonic metals. We find substantial…
Nonlocal and nonlinear plasmonics in atomically thin heterostructures
University of Southern Denmark（南丹麦大学）；POLIMA—Center for Polariton-driven Light–Matter Interactions, University of Southern Denmark（极化激元驱动光-物质相互作用中心，南丹麦大学）；Danish Institute for Advanced Study, University of Southern Denmark（丹麦高级研究院，南丹麦大学）
We present a detailed appraisal of the optical and plasmonic properties of ordered alloys of the form Au$_{x}$Ag$_{y}$Cu$_{1-x-y}$, as predicted by means of first-principles many-body perturbation theory augmented by a semi-empirical Drude-Lorentz model. In benchmark simulations on elemental Au, Ag, and Cu, we find that the random-phase approximation (RPA) fails to accurately describe inter-band transitions when it is built upon semi-local approximate Kohn-Sham density-functional theory (KS-DFT) band-structures. We show that non-local electronic exchange-correlation interactions sufficient to …
Plasmonic Metasurfaces for Magnetic Skyrmion Control via the Inverse Faraday Effect
Sorbonne Université, CNRS, Institut des NanoSciences de Paris, INSP（索邦大学，法国国家科学研究中心，巴黎纳米科学研究所）；School of Optoelectronic Engineering and Instrumentation Science, Dalian University of Technology（大连理工大学光电工程与仪器科学学院）；Instituto de Engenharia de Sistemas E Computadores – Microsistemas e Nanotecnologias (INESC MN)（系统计算机工程研究所-微系统与纳米技术）；Institute of Condensed Matter and Nanosciences, Université Catholique de Louvain（天主教鲁汶大学凝聚态与纳米科学研究所）；School of Electronic and Information Engineering, Ningbo University of Technology（宁波理工学院电子与信息工程学院）；Blackett Laboratory, Department of Physics, Imperial College London（伦敦帝国理工学院物理系布莱克特实验室）；London Centre for Nanotechnology, Imperial College London（伦敦帝国理工学院伦敦纳米技术中心）；Laboratoire Albert Fert, CNRS, Thales, Université Paris-Saclay（巴黎萨克雷大学CNRS-Thales阿尔伯特·费尔特实验室）
Energy carrier evolution is crucial for material performance. Ultrafast microscopy has been widely applied to visualize the spatiotemporal evolution of energy carriers. However, direct imaging of small amounts of energy carriers on nanoscale remains difficult due to extremely weak transient signals. Here we present a method for ultrasensitive and high-throughput imaging of energy carrier evolution in space and time. This method combines femtosecond pump-probe techniques with interferometric scattering microscopy (iSCAT), named Femto-iSCAT. The interferometric principle and unique spatially-mod…
We consider plasmonic metasurfaces constituted by an arbitrary periodic arrangement of spherical metallic nanoparticles. Each nanoparticle supports three degenerate dipolar localized surface plasmon (LSP) resonances. In the regime where the interparticle distance is much smaller than the optical or near-infrared wavelength associated with the LSPs, the latter couple through the dipole-dipole interaction and form collective plasmonic modes which extend over the whole metasurface. Within a Hamiltonian model which we solve exactly, we derive general expressions which enable us to extract analytic…
A non-perturbative model for graphene optical nonlinearity is developed for the study of ultrafast pulse propagation along a monolayer, as in the case of graphene-comprising nanophotonic integrated waveguides. This graphene `hot electron' model (GHEM) builds upon earlier work, based on the Fermi-Dirac framework for 2D semiconductors, which was aimed mainly at steady-state absorptive response of a monolayer under free-space laser-beam illumination. Our extension adapts the GHEM to in-plane light-matter interaction along graphene monolayers under intense ps-pulse excitation that leads to the car…
Ultrafast All-Optical Polarization Control via Symmetry Breaking in an Au Nanorod Dimer Metamaterial
Institute of Nanoscience and Nanotechnology, National Center for Scientific Research “Demokritos”（纳米科学与技术研究所，国家科学研究中心“德莫克里斯”）；Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, NHRF（理论与物理化学研究所，希腊国家研究基金会）
Ultrafast science and technology have brought in burgeoning opportunities to optical metrology, strong-field physics, non-equilibrium physics, etc., through light-matter interaction due to ever-advancing temporal resolution and peak power of ultrafast laser. The superior temporal and spectral resolution, has brought forth pump-probe spectroscopy for ultrafast dynamic study of transient states in various intriguing materials, such as quantum materials, metamaterials, and plasmonic materials, by directly reporting spectroscopic complex response function, using either time- or frequency-domain- b…
