25 research outputs found
Resonance-enhanced transmission of surface plasmon polariton wave-packets through metal-insulator-metal nanocavities
No full textSpectral and temporal modulations of femtosecond SPP wave packets induced by resonant transmission/reflection interactions with metal-insulator-metal nanocavities.
Get PDFjournal articl
Resonance order-dependent plasmon-induced transparency in orthogonally-arranged nanoscale cavities
No full textIn this study, we investigate plasmon-induced transparency (PIT) in a resonator structure consisting of two orthogonally-arranged metal-insulator-metal (MIM) nanocavities with the aim of spectral modulation of a specific resonant order of the resonator. Our FDTD simulations demonstrate that when both cavities in this structure resonate at the same frequency, the PIT effect can be used to induce spectral modulation. This spectral modulation depends on the resonance order of the cavity coupled directly to the external field, occurring when first-order resonance is exhibited, but not with second-order resonance. We confirmed that this behavior is caused by the discrepancies between odd-order and even-order resonances using classical mechanical models analogous to the nanocavities. By tuning the resonance frequency and resonance order of the cavities, one can modulate the spectrum of the resonator structure in an order-selective manner
Spectral tuning of SPP reflection by quasi-symmetric metal nano-block arrays
No full textWe investigate the spectral tuning of the SPP wave packets by quasi-symmetric arrays composed of metal blocks with two different structural lengths. The FDTD simulations showed a resonance phenomenon in the gap between the blocks when the two blocks have different lengths in the longitudinal direction. Furthermore, the resonance of the gap resulted in a significant spectral modulation of the reflected SPP wave that depended on the structural length and positional relationship of the blocks
表面プラズモンポラリトン波束の時間-空間制御
Get PDF筑波大学University of Tsukuba博士（理学）Doctor of Philosophy in Science2022【要旨】thesi
Experimental realization of Lorentz boosts of space-time wave packets
Get PDFIt is now well-understood that a Lorentz boost of a spatially coherent
monochromatic optical beam yields a so-called space-time wave packet (STWP): a
propagation-invariant pulsed beam whose group velocity is determined by the
relative velocity between the source and observer. Moreover, the Lorentz boost
of an STWP is another STWP, whose group velocities are related by the
relativistic law for addition of velocities typically associated with massive
particles. We present an experimental procedure for testing this prediction in
both the subluminal and superluminal regimes that makes use of spatio-temporal
Fourier synthesis via a spatial light modulator. Our approach enables realizing
the change in temporal bandwidth, the invariance of the spatial bandwidth, the
concomitant change in the spatio-temporal wave-packet envelope, and the change
in group velocity that all accompany a Lorentz boost of a monochromatic optical
beam. The only consequence of the Lorentz boost not captured by this
methodology is the Doppler shift in the optical carrier. This work may provide
an avenue for further table-top demonstration of relativistic transformations
of optical fields.Comment: 13 pages, 10 figure
表面プラズモンポラリトン波束の時間-空間制御
Get PDF筑波大学University of Tsukuba博士（理学）Doctor of Philosophy in Science2022この博士論文は内容の要約のみの公開（または一部非公開）になっていますdoctoral thesi
Spatiotemporal control of surface plasmon polariton wave packets with nanocavities
No full textModulation of the optical index by means of atomic and material resonances provides a basis for controlling light propagation in natural and artificially fabricated materials. In addition, recent advances in the tuning of spatiotemporal couplings of ultrashort laser pulses have enabled almost arbitrary control over the group velocity of light. Here, using femtosecond time-resolved microscopy and numerical calculations, we investigate the spatiotemporal dynamics of a surface plasmon polariton wave packet (SPP WP) that interacts with a plasmonic nanocavity. The nanocavity consists of metal-insulator-metal multilayer films that function as subwavelength meta-atom possessing tunable discretized eigenmodes. When a chirp-induced femtosecond SPP WP is incident on a nanocavity, only the spectral component matching the resonance energy is transmitted. This spectral clipping effect is accompanied by a spatial shift of the WP. The shift can be adjusted in either the positive or negative direction by controlling the resonance energy or the chirp. If this spatial shift is regarded as a modulation of the apparent group velocity in the nanocavity, the range of modulation includes superluminal, subluminal, and negative group velocities
Designing rotational motion of charge densities on plasmonic nanostructures excited by circularly polarized light
No full textRotational motion of charges in plasmonic nanostructures plays an important role in transferring angular momentum between light and matter on the nanometer scale. Although sophisticated control of rotational charge motion has been achieved using spatially structured light, its extension to simultaneous excitation of the same charge motion in multiple nanostructures is not straightforward. In this study, we perform model calculations to show that spatially homogeneous circularly polarized (CP) light can excite rotational charge motions with a high degrees of freedom by exploiting the rotational symmetry of the plasmonic structure and that of the plasmon mode. Finite-difference time-domain simulations demonstrate selective excitation of rotational charge motion for both isolated nanoplates and periodic array structures, showing that complex charge rotations can be manipulated by plane CP waves in a wide range of plasmonic structures
