Universal optimal transmission of light through disordered materials Invited Paper Paper Author s : Show Abstract. We experimentally demonstrate increased diffuse transmission of light through strongly scattering materials. The results are in excellent quantitative agreement with random matrix theory.
Vellekoop and A. Mosk, Phys. I will further present new results on focusing light inside strongly scattering materials. Metamaterial and plasmonic composites have led to the realization that new possibilities abound for creating effective materials displaying functional electromagnetic properties not realized by naturally occurring materials. Recently, we have extended these ideas through judicious combination with MEMS technology. This has enabled the creation of non-planar flexible composites and micromechanically active structures where the orientation of the electromagnetically resonant elements can be precisely controlled with respect to the incident field.
Such adaptive structures are the starting point for the development of a host of new functional electromagnetic devices which take advantage of designed and tunable anisotropy. Terahertz transmission through a nanogap Paper Author s : Show Abstract. Terahertz time domain spectroscopy is performed to probe transmittance over a frequency range of 0.
Polarization dependent terahertz spectroscopy of a single subwavelength hole in thin metallic film Paper Author s : Show Abstract. We investigate the optical properties of a subwavelength hole with circular shape in a thin metallic film, using time-domain terahertz spectroscopy. The microscopic origin of the hole plasmon resonance is a collective state formed by propagating thin film surface plasmons of wavelengths equal to integer fractions of the hole diameter.
We show that the plasmon resonance depend strongly on the polarization of the incident light. We also demonstrate the first experimental observation of the optical coupling between antibonding film plasmon modes and perpendicularly polarized light to the film surface. We demonstrate a new far-field superlens based on the Indefinite Permittivity metamaterial consisting of SiO2 and SiC films. Using interferometric multi-beam multi-detector technique, deeply sub-wavelength resolution can be accomplished.
We also demonstrate critically coupled surface phonon-polariton excitation in SiC, leading to maximum electric field enhancement. A double-scan of wavelength and incidence angle in the Otto configuration demonstrates critical coupling for two air gaps. It is theoretically demonstrated that critical coupling occurs when coupling loss into the prism is equal to the resistive loss in SiC.
The concept of critical coupling is then used to demonstrate SPP sensing of different chemical substances. The advantage of mid-IR sensing is that the index difference between different substances in mid-IR is much larger than in the visible. THz anomalous transmission in plasmonic lattices: incidence angle dependence Paper Author s : Show Abstract.
The phenomenon of anomalous transmission through subwavelength aperture arrays in metallic films is thought to be mediated by surface plasmon polaritons SPP on the film surfaces. Using terahertz time-domain spectroscopy we systematically studied the anomalous transmission spectrum through plasmonic lattices as a function of the incidence angle, theta of the impinging beam. We observed splitting of the various transmission resonances into two resonance branches when theta deviates from normal incidence depending on the polarization direction of the beam.
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We show that the splitting is not related to dispersion relation of different SPP branches, but the interference properties of SPP on the metal surface. The dependence of the split resonant frequencies vs. Symposium-wide Plenary Session.
Monday 3 August Show All Abstracts. Session 5: Active Nanoplasmonics and Related Subjects. Here we show that phase changes in novel chalcogenide glasses can be used to actively control signals in plasmonic devices. In this paper we theoretically obtain an expression for the dc force exerted on electrons in metal nanostructures by propagating surface plasmon polaritons SPPs. This expression is general and can be applied in the case of non-local or tensorial relation of polarization and electric field in the metal.
We show that the SPP-induced force acting on electrons in a metal wire leads to dc potential between the ends of the wire. We compute the resulting electromotive force including the non-local effects into our consideration. Nanoscale optical field localization by resonantly focused plasmons Paper Author s : Show Abstract.
We experimentally demonstrate use of plasmonic resonant phenomena combined with strong field localization to enhance efficiency of confining optical fields in a Si waveguide. The near-field optical measurements of the fabricated RNFA using heterodyne near-field scanning optical microscope validate the theoretical predictions showing strong optical field localization. Transparent conducting oxides for active plasmonics Paper Author s : Show Abstract. The metal in plasmonic structures is replaced with a TCO transparent conducting oxide , which exhibits a carrier density high enough to support the plasmonic modes, yet capable of complex index modulation by voltage application to form active devices.
The measured IZO permittivity and carrier density indicates that these films can support surface plasmon polariton modes in the near IR region. We demonstrate that surface plasmons can be employed for efficient beam shaping of semiconductor lasers. Using Quantum Cascade Lasers as a model system, we show that by defining suitable metallic sub-wavelength slits and a gratings on their facet, a highly collimated beam can be achieved. Polarization control with metallic nanopatterning is also demonstrated.
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Extension of these concepts to optical fiber based light sources will be also discussed. Detection and simultaneous structural identification of a single molecule as well as quantification of small amounts of matter by counting single molecules represent the ultimate limits in chemical analysis. Furthermore, bioanalytics and nanosciences require molecular structural information from extremely small volumes. This talk shows that Surface enhanced Raman scattering SERS using excitation in the near infrared NIR and nano-aggregates made from silver and gold spheres as enhancing structures has the potential to address all these goals.
Nanoplasmonics from attoseconds to terahertz Paper Author s : Show Abstract. Single-molecule detection through controlled ultrasensitive surface-enhanced Raman scattering Paper Author s : Show Abstract. The ability of resolving the identity of molecular species in low concentration renders optical SERS analysis an excellent tool for ultra-sensitive detection.
The low cross-section of Raman molecular signals is typically overcome by means of large amplification especially at randomly encountered hot spots, particularly in nanostructured metals.
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However, the detailed geometry and performance of such hot spots is not well understood, thus hindering the availability of controlled, quantitative SERS analysis. Employing standard nanolithography, we produced arrays of stacked nanodisks of Au on VO2. Analysis of temperature-resolved SERS spectra allowed for close examination of the phase transition of VO2 at size scales where only few or single crystalline domains were present.
We have also employed finite-difference, time-domain FDTD calculations to understand both thermal and plasmonic interactions.
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This composite structure presents a versatile platform for future studies in plasmonic phenomena. We report on the manufacturing and optical properties of 3D metallic metamaterials that exhibit extremely narrow resonances. Therefore, they allow tailoring novel optical sensors that are extremely sensitive to the surrounding environment.
By changing local electric fields and their modifications through refractive index changes, we can detect glucose levels, the presence of hydrogen, as well as single layers of biomolecules. We report on the construction of such sensors and compare their figures of merit with other plasmonic sensor types. We calculate the extinction spectra of nanostars and nanobipyramids in water solution, and investigate the shift of the LSPR peak upon absorption of a single protein molecule at different locations on the surfaces of the particle.
For protein absorption near the sharp tips of the nanoparticles, the LSPR shift is found to be sufficiently large to induce a measurable shift in the extinction spectrum. Experimental evidence for such single molecule absorption events will be presented. Fluctuation in surface enhanced Raman scattering intensity due to plasmon related heating effect Paper Author s : Show Abstract.
This reduction in the spectral intensity is irreversible but never lost completely to a zero value and can be attributed to the plasmon induced heating effect. In this paper we demonstrate this effect by studying the SERS signal from a common Raman active dye absorbed onto a variety of substrates that contain uniform nano-roughned silver coating and also with bimetallic coating of silver and gold.
Similar observation was made for the dye absorbed on to metal colloids. The affect of using different types of supporting substrates such as glass and thin copper plate is also discussed. Tuesday 4 August Show All Abstracts.
Design of nanostructures for high harmonic generation by localized surface plasmon resonance Paper Author s : Show Abstract. Despite the lack of a measurable signal in smooth 15 nm thick Ag layers, the enhanced nonlinear response is attributed to electron temperature changes in the Ag layers that are amplified by plasmonic coupling at the metal-dielectric interface. Local melting effects on phospholipid membranes using plasmonic heating Paper Author s : Show Abstract.
Optothermal heating of metallic nanoparticles has found a number of applications such as remote release and biomolecular analysis. Still, the full potential to locally heat nanoscopic portions of matter and thereby obtain information and manipulation capabilities on thermal processes at the nano-scale remains greatly unexplored.
Here, we use single, functionalized gold nanoparticles as optical nano-heat-generators on phospholipid membranes. We demonstrate local heating by inducing membrane gel-fluid phase transitions in the nanoparticle vicinity. Further, by combining heat and optical manipulation we guide the nanoparticles over the membrane, making a versatile nano-tool for the examination and manipulation of processes at the nanoscale. True nano-plasmonics: from nanoscale integrated circuits to nano-photovoltaics Keynote Presentation Keynote Presentation Paper Author s : Show Abstract.
With nanoscale fabrication techniques advancing, the manipulation of light in plasmonic nanostructures at the true nanoscale becomes a reality. We will demonstrate: a confinement of light in sub nm plasmonic whispering gallery resonators made using focussed ion beam milling, imaged using cathodoluminescence spectroscopy at a spatial resolution of only 10 nm; b nm wide coaxial metal channel waveguides with a negative index of refraction as large as -9; c thin-film solar cells with enhanced efficiency using suitably engineered nanoparticle arrays, and d the assembly of metallic nanoparticles using a DNA templating technique at a scale of only 1 nm.
Session 8: Ultrafast Nanoplasmonics. Simultaneous spatial and temporal control of the local excitation of a nanostructure using polarization shaped laser pulses Keynote Presentation Keynote Presentation Paper Author s : Show Abstract. We demonstrate experimentally that polarization shaped laser pulses allow tailoring the local excitation of a nanostructure with subwavelength spatial and femtosecond temporal resolution.
Time-resolved two-photon photoemission microscopy is used to monitor the local excitation of a nanostructure by a polarization shaped pump pulse.
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The time-resolved signal shows a significant contrast for the emission from three different regions in the emission pattern of an individual nanostructure, demonstrating a switching of the local excitation maximum in the fs time scale. The polarization-shaped laser pulses are fully characterized and thus the relationship between photoemission pattern and the transient polarization state can be determined.
So far, the spatiotemporal dynamics of optical fields localized on the nanoscale nanoplasmonic field have been hidden from direct access in the real space and time domain. An approach, which combines photoelectron emission microscopy and attosecond streaking spectroscopy and provides direct and non-invasive access to the nanoplasmonic field with nanometer-scale spatial resolution and temporal resolution on the order of attoseconds, has been proposed.
Probing surface plasmon dynamics by 80 asec XUV pulses is discussed. Saturable absorption of femtosecond laser pulses at surface plasmon resonance in gold nanoshells Paper Author s : Show Abstract. In this work, we present an investigation of the nonlinear optical properties of nanoshells of different size in solutions using a single beam z-scan method at a wavelength of nm with laser duration of fs. It is found that, in general, they behave as saturable absorbers, as demonstrated for other kind of nanoparticles of different metals and shapes.