Plasmonics

High Li+ conducting ceramics

by miss riaz

Infrared Nanoscopy of Dirac Plasmons at the Graphene–SiO2 Interface

by Zhe Fei

Zhe Fei*†, Gregory O. Andreev*†, Wenzhong Bao‡, Lingfeng M. Zhang†§, Alexander S. McLeod†, Chen Wang, Margaret K. Stewart†, Zeng Zhao‡, Gerardo Dominguez, Mark Thiemens, Michael M. Fogler†, Michael J. Tauber, Antonio H. Castro-Neto□, Chun Ning Lau‡, Fritz Keilmann■, and Dimitri N. Basov†

We report on infrared (IR) nanoscopy of 2D plasmon excitations of Dirac fermions in graphene. This is achieved by... more We report on infrared (IR) nanoscopy of 2D plasmon excitations of Dirac fermions in graphene. This is achieved by confining mid-IR radiation at the apex of a nanoscale tip: an approach yielding 2 orders of magnitude increase in the value of in-plane component of incident wavevector q compared to free space propagation. At these high wavevectors, the Dirac plasmon is found to dramatically enhance the near-field interaction with mid-IR surface phonons of SiO2 substrate. Our data augmented by detailed modeling establish graphene as a new medium supporting plasmonic effects that can be controlled by gate voltage.

Gate-tuning of graphene plasmons revealed by infrared nano-imaging

by Zhe Fei

Z. Fei, A. S. Rodin, G. O. Andreev, W. Bao, A. S. McLeod, M. Wagner, L. M. Zhang, Z. Zhao, G. Dominguez, M. Thiemens, M. M. Fogler, A. H. Castro-Neto, C. N. Lau, F. Keilmann, D. N. Basov

Surface plasmons are collective oscillations of electrons in metals or semiconductors enabling confinement and control... more Surface plasmons are collective oscillations of electrons in metals or semiconductors enabling confinement and control of electromagnetic energy at subwavelength scales. Rapid progress in plasmonics has largely relied on advances in device nano-fabrication, whereas less attention has been paid to the tunable properties of plasmonic media. One such medium-graphene-is amenable to convenient tuning of its electronic and optical properties with gate voltage. Through infrared nano-imaging we explicitly show that common graphene/SiO2/Si back-gated structures support propagating surface plasmons. The wavelength of graphene plasmons is of the order of 200 nm at technologically relevant infrared frequencies, with a propagation length several times this distance. We have succeeded in altering both the amplitude and wavelength of these plasmons by gate voltage. We investigated losses in graphene using plasmon interferometry: by exploring real space profiles of plasmon standing waves formed between the tip of our nano-probe and edges of the samples. Plasmon dissipation quantified through this analysis is linked to the exotic electrodynamics of graphene. Standard plasmonic figures of merits of our tunable graphene devices surpass that of common metal-based structures.

Quantitative analysis of localized surface plasmons based on molecular probing

by Prashant Jain

Epitaxial self-alignment: A new route to hybrid active plasmonic nanostructures

by Adam Urbanczyk

Concepts of lateral ordering of epitaxial semiconductor quantum dots (QDs) are for the first time transferred to... more Concepts of lateral ordering of epitaxial semiconductor quantum dots (QDs) are for the first time transferred to hybrid nanostructures for active plasmonics. We review our recent research on the self-alignment of epitaxial nanocrystals of In and Ag on ordered one-dimensional In(Ga)As QD arrays and isolated QDs by molecular beam epitaxy. By changing the growth conditions the size and density of the metal nanocrystals are easily controlled and the surface plasmon resonance wavelength is tuned over a wide range in order to match the emission wavelength of the QDs. Photoluminescence measurements reveal large enhancement of the emitted light intensity due to plasmon enhanced emission and absorption down to the single QD level.

Self-aligned epitaxial metal-semiconductor hybrid nanostructures for plasmonics

by Adam Urbanczyk

We demonstrate self-alignment of epitaxial Ag nanocrystals on top of low-density near-surface InAs quantum dots (QDs)... more We demonstrate self-alignment of epitaxial Ag nanocrystals on top of low-density near-surface InAs quantum dots (QDs) grown by molecular beam epitaxy. The Ag nanocrystals support a surface plasmon resonance that can be tuned to the emission wavelength of the QDs. Photoluminescence measurements of such hybrid metal-semiconductor nanostructures reveal large enhancement of the emission intensity. Our concept of epitaxial self-alignment enables the integration of plasmonic functionality with electronic and photonic semiconductor devices operating down to the single QD level.

Analytical properties of the plasmon decay profile in a periodic metal-nanoparticle chain

by Kin Hung Fung

Subwavelength image manipulation through an oblique layered system

by Kin Hung Fung

Exciting Multiple Plasmonic Resonances by a Double-layered Metallic Nanostructure

by Kin Hung Fung

A Thin Film Broadband Absorber Based on Multi-sized Nanoantennas

by Kin Hung Fung

Application of Plasmonic Bowtie Nanoantenna Arrays for Optical Trapping, Stacking, and Sorting

by Kin Hung Fung

Ultra-broadband Light Absorption by a Sawtooth Anisotropic Metamaterial Slab

by Kin Hung Fung

Chiral Photonic and Plasmonic Structures

by Kin Hung Fung

Painting by Numbers: Nanoparticle‐Based Colorants in the Post‐Empirical Age

by Robin Klupp Taylor

One‐Pot Colloidal Synthesis of Plasmonic Patchy Particles

by Robin Klupp Taylor

Silver-assisted colloidal synthesis of gold patchy particles with tunable patchiness

by Robin Klupp Taylor

Huixin Bao, Benjamin Butz, Zhou Zhou, Erdmann Spiecker, Martin Hartmann, Robin Klupp Taylor

Published in Langmuir - http://pubs.acs.org/doi/abs/10.1021/la204762z

Patchy particles possessing heterogeneous surface composition show great promise as self-organizing building blocks... more Patchy particles possessing heterogeneous surface composition show great promise as self-organizing building blocks for new classes of hierarchical functional structures. A major hurdle is the scalable synthesis of stable patches on nanosized core particles with arbitrarily defined patch number and coverage. So far, few methods have been reported which could be expected to meet these challenges. Recently we described the heterogeneous nucleation and growth of silver patches on silica nanospheres via a template free colloidal route. The patches produced, although tunable in size and number and showing interesting plasmon resonant properties, were rather unstable and degraded rapidly during attempts to process them further. In the present work, therefore, we set out to explore if related approaches can be employed to produce patchy particles involving gold, which is known to be more stable. The differences between typical patch precursors Ag+ and [AuClx(OH)4-x]- and their respective interactions with amorphous silica make this a significant challenge. We show that preformed small silver patches in addition to the presence of a reducing agent are necessary for the formation of gold patches conformal to the silica nanosphere surface. Systematic study of the process parameters and their influence on the patchiness as well as in-depth analytical TEM investigation of the patch composition reveal that patches spread over the silica surface via a cycle of galvanic dissolution and redeposition of silver.The resulting gold patchy particles remain stable during subsequent storage or washing and display tunable plasmon resonances within the visible and near-IR spectrum.

Triangular Core-shell Structure Ag@AgAu

by Mohammad Mehdi Shahjamali

Novel Triangular Ag@AgAu nanoparticles were synthesized in aqueous solution using a seed-mediated approach in the... more Novel Triangular Ag@AgAu nanoparticles were synthesized in aqueous solution using a seed-mediated approach in the absence of any surfactants. The formation of the gold layer on the silver nanoprism seeds leads to structures with better stability and tunability. The triangular Ag@AgAu has been synthesized by the reduction of hydrogen tetrachloraurate onto Ag nanoprisms. This unusual structure exhibited interesting optical properties and the extinction spectra can be engineered in a broad range based upon the thickness of the outer AuAg shell.

Gold Coating of Silver Nanoprisms

by Mohammad Mehdi Shahjamali

Core–shell Ag@Au nanoprisms are prepared through a surfactant-free seed-mediated approach by taking advantage of the... more Core–shell Ag@Au nanoprisms are prepared through a surfactant-free seed-mediated approach by taking advantage of the anisotropic structure of silver nanoprisms as seeds. The gold coating on the silver nanoprism surface is achieved by using hydroxylamine as a mild reducing agent, and the final fully gold-coated prism structures are confirmed by microscopic and spectroscopic characterization. The resulting Ag@Au core–shell structure preserves the optical signatures of nanoprisms and offers versatile functionality and particularly better stability against oxidation than the bare silver nanoprism. The surface plasmon resonances of the core–shell Ag@Au nanoprisms can be tuned throughout the visible and near-IR range as a function of the Au shell thickness. Such tailorable optical features and surfactant-free gold shells have great potential applications in biosensing and bioimaging.

Laser-induced scanning tunneling microscopy: Linear excitation of the junction plasmon

by Desiré Whitmore

A subwavelength slit as a quarter-wave retarder

by Philip Chimento

Co-authors: Nikolay V. Kuzmin, Johan Bosman, Paul F. A. Alkemade, Gert W. 't Hooft, Eric R. Eliel
Published in Optics Express, Vol. 19, Issue 24, pp. 24219-24227 (2011)

We have experimentally studied the polarization-dependent transmission properties of a nanoslit in a gold film as a... more We have experimentally studied the polarization-dependent transmission properties of a nanoslit in a gold film as a function of its width. The slit exhibits strong birefringence and dichroism. We find, surprisingly, that the transmission of the polarization parallel to the slit only disappears when the slit is much narrower than half a wavelength, while the transmission of the perpendicular component is reduced by the excitation of surface plasmons. We exploit the slit’s dichroism and birefringence to realize a quarter-wave retarder.