Femtosecond microscopy of localized and propagating surface plasmons in silver gratings

Kubo, Atsushi; Jung, Yun Suk; Kim, Hong Koo; Petek, Hrvoje

doi:10.1088/0953-4075/40/11/s02

Cited by 77 publications

(72 citation statements)

References 52 publications

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“…Therefore, to assess the function of a single slit coupler in broadband SPP wave packet (WP) excitation, it is necessary to describe the fundamental physics of the incident and scattered fields at single slit structures subject to the excitation with ultrafast pulses at an oblique excitation geometry. [34][35][36][37][38][39] In this paper, we investigate the SPP WPs excited at single slits formed in an 80 nm silver film by 10 fs light pulses with a 65 o angle of incidence. Experimental and theoretical studies are focused on the two-photon photoemission electron microscopy (2P-PEEM) imaging of the interference pattern between the incident light pulse and the excited SPP WPs.…”

Section: Introductionmentioning

confidence: 99%

Imaging of surface plasmon polariton fields excited at a nanometer-scale slit

et al. 2011

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Nonlinear two-photon photoemission electron microscopy is used to image surface plasmon polariton (SPP) wave packets excited by an obliquely incident laser pulse (~10 fs) at a single slit fabricated in a thin silver film. We image the forward propagating polarization grating formed by the coherent superposition of the external excitation pulse and the SPP wave packet fields. By systematically varying the coupling slit width from sub-to multiple-wavelength scale, we observe a modulated increase of the grating intensity, which is phenomenologically accounted for by distinct contributions to the forward coupling efficiency from the incident to the SPP waves. Full-wave, vectorial finite-difference time-domain (FDTD) simulation of the experiments is in good agreement with the experimental observations and explains their origin. In particular, the FDTD simulation illustrates detailed spatial variation of the polarization grating as a function of the geometry of the slit under excitation by ultrafast laser pulses at an oblique incidence.2

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Section: Introductionmentioning

confidence: 99%

Imaging of surface plasmon polariton fields excited at a nanometer-scale slit

et al. 2011

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“…Considering the femtosecond scale lifetimes of SPPs, a detailed understanding of the dynamics of the coupled SPP excitation and propagation is essential for applications in, e.g., coherent control of ultrafast plamonics. 6,12,36,37 To explore in a uniform fashion both the excitation and the subsequent propagation dynamics of the SPP waves, which can be directly compared with experiments, it is useful to apply a method which is capable of: (i) incorporating the exact excitation geometry; (ii) separating the scattered surface waves from the incident field; and (iii) tracking the field distributions in time. The goal is to characterize total surface fields that can be directly compared with nonperturbative methods, such as PEEM imaging, on similar nanometer spatial and femtosecond temporal scales.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of coupled plasmon polariton wave packets excited at a subwavelength slit in optically thin metal films

et al. 2012

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We study by numerical simulations the excitation and propagation dynamics of coupled surface plasmon polariton (SPP) wave packets (WPs) in optically thin Ag films and a bulk Ag/vacuum interface under the illumination of a subwavelength slit by 400 nm continuous wave (cw) and femtosecond pulsed light. The generated surface fields include contributions from both SPPs and quasi-cylindrical waves, which dominate in different regimes. We explore aspects of the coupled SPP modes in Ag thin films, including symmetry, propagation and attenuation, and the variation of coupling with incident angle and film thickness. Simulations of the electromagnetic transients initiated with femtosecond pulses reveal new features of coupled SPP WP generation and propagation in thin Ag films. Our results show that, under pulsed excitation, the SPP modes in an Ag thin film break up into two distinct bound surface wave packets characterized by marked differences in symmetries, group velocities, attenuation lengths and dispersion properties. The nanometer spatial and femtosecond temporal scale excitation and propagation dynamics of the coupled SPP WPs are revealed in detail by movies recording the evolution of their transient field distributions.2

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“…Typical examples are electron/X-ray diffraction 147150 and electron microscopy 144,145,151 combined with ultrashort pulsed light sources. Nanooptical methods are expected to provide valuable information complementary to that by the advanced methods mentioned above, and further developments are highly desired to advance nano-photosciences.…”

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Nanooptical Studies on Physical and Chemical Characteristics of Noble Metal Nanostructures

Okamoto¹

2013

Bulletin of the Chemical Society of Japan

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Studies on physical and chemical properties of noble metal nanostructures, mainly by near-field optical microscopy and spectroscopy, are described. Near-field optical microscopy provides optical observation methodology with a spatial resolution in nanometer regime beyond the diffraction limit of light. We developed near-field imaging systems equipped with various light sources including ultrashort pulsed lasers, which enables advanced nonlinear and ultrafast near-field measurements as well as conventional near-field imaging. In particular, near-field two-photon excitation imaging was shown to provide a convenient tool to visualize the enhanced optical fields in the vicinities of metal nanostructures. With these methods we demonstrated that nanoscale optical field structures in metal nanostructures can be directly visualized. For single noble metal nanoparticles, such as gold nanorods as typical examples, plasmon standing wave functions were visualized. Ultrafast imaging revealed that sub-picosecond relaxation was reflected on the plasmon wave function images through thermally induced dielectric function changes of the metal. In some cases optical field distribution features arising from the lightning rod effects were observed, depending on the resonance conditions of the incident wavelengths with the plasmon modes. We also found anomalous near-field transmission phenomenon for nanoapertures blocked by nanodisks near the plasmon resonance wavelengths, which arise from the efficient near-field to propagating-field conversion ability of the nanodisks. In assembled nanoparticles, enhanced optical fields at the gap sites between the particles were visualized, which elucidates experimentally the mechanism of surface-enhanced Raman scattering. The characteristic field distributions in many particle assemblies were also observed and analyzed. Through these studies, we established a valuable methodology to investigate optical and spectroscopic properties of metal nanostructures, and the information obtained is available only by optical measurements with high spatial resolution.

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Femtosecond microscopy of localized and propagating surface plasmons in silver gratings

Cited by 77 publications

References 52 publications

Imaging of surface plasmon polariton fields excited at a nanometer-scale slit

Imaging of surface plasmon polariton fields excited at a nanometer-scale slit

Dynamics of coupled plasmon polariton wave packets excited at a subwavelength slit in optically thin metal films

Nanooptical Studies on Physical and Chemical Characteristics of Noble Metal Nanostructures

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