Fundamentals of Plasmonics.- Electromagnetics of Metals.- Surface Plasmon Polaritons at Metal / Insulator Interfaces.- Excitation of Surface Plasmon Polaritons at Planar Interfaces.- Imaging Surface Plasmon Polariton Propagation.- Localized Surface Plasmons.- Electromagnetic Surface Modes at Low Frequencies.- Applications.- Plasmon Waveguides.- Transmission of Radiation Through Apertures and Films.- Enhancement of Emissive Processes and Nonlinearities.- Spectroscopy and Sensing.- Metamaterials and Imaging with Surface Plasmon Polaritons.- Concluding Remarks.

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Plasmonics: Fundamentals and Applications

The unprecedented ability of nanometallic (that is, plasmonic) structures to concentrate light into deep-subwavelength volumes has propelled their use in a vast array of nanophotonics technologies and research endeavours. Plasmonic light concentrators can elegantly interface diffraction-limited dielectric optical components with nanophotonic structures. Passive and active plasmonic devices provide new pathways to generate, guide, modulate and detect light with structures that are similar in size to state-of-the-art electronic devices. With the ability to produce highly confined optical fields, the conventional rules for light-matter interactions need to be re-examined, and researchers are venturing into new regimes of optical physics. In this review we will discuss the basic concepts behind plasmonics-enabled light concentration and manipulation, make an attempt to capture the wide range of activities and excitement in this area, and speculate on possible future directions.

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Plasmonics for extreme light concentration and manipulation.

Cell membranes display a tremendous complexity of lipids and proteins designed to perform the functions cells require. To coordinate these functions, the membrane is able to laterally segregate its constituents. This capability is based on dynamic liquid-liquid immiscibility and underlies the raft concept of membrane subcompartmentalization. Lipid rafts are fluctuating nanoscale assemblies of sphingolipid, cholesterol, and proteins that can be stabilized to coalesce, forming platforms that function in membrane signaling and trafficking. Here we review the evidence for how this principle combines the potential for sphingolipid-cholesterol self-assembly with protein specificity to selectively focus membrane bioactivity.

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Lipid Rafts As a Membrane-Organizing Principle

We present single-molecule, real-time sequencing data obtained from a DNA polymerase performing uninterrupted template-directed synthesis using four distinguishable fluorescently labeled deoxyribonucleoside triphosphates (dNTPs). We detected the temporal order of their enzymatic incorporation into a growing DNA strand with zero-mode waveguide nanostructure arrays, which provide optical observation volume confinement and enable parallel, simultaneous detection of thousands of single-molecule sequencing reactions. Conjugation of fluorophores to the terminal phosphate moiety of the dNTPs allows continuous observation of DNA synthesis over thousands of bases without steric hindrance. The data report directly on polymerase dynamics, revealing distinct polymerization states and pause sites corresponding to DNA secondary structure. Sequence data were aligned with the known reference sequence to assay biophysical parameters of polymerization for each template position. Consensus sequences were generated from the single-molecule reads at 15-fold coverage, showing a median accuracy of 99.3%, with no systematic error beyond fluorophore-dependent error rates.

/pdf/real-time-dna-sequencing-from-single-polymerase-molecules-3o0n2kc430.pdf

Real-Time DNA Sequencing from Single Polymerase Molecules

The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

http://ieeexplore.ieee.org/iel5/6354/16969/00781867.pdf

Photonic crystals

Consequences of the columnar microstructure of dielectric thin films deposited by conventional vacuum evaporation are discussed. A model associated with the columns is used together with in situ and in air measurements to show that the anisotropy of Ion Assisted Deposited TiO 2 films changes with ion energy. Moreover TiO 2 and Ta 2 O 5 layers deposited by conventional evaporation present reversible disturbances of their optical properties when illuminated with high power flux. A model taking into account both thermal and nonlinear properties (localized optical Kerr type effect) of the prism coupler system is used to explain the measurements and to estimate the nonlinear refractive index coefficient of different thin films.

Interpreting anisotropy and disturbances of optical properties of thin films in terms of layer microstructure

We investigate theoretically and experimentally the optical properties of planar Ta2O5/SiO2 multilayer structures implanted with rare earth ions such as erbium and praseodymium. We demonstrate that the spontaneous emission can be strongly enhanced in a direction normal to the layers if the luminescent ions are located in the spacer of a resonant Fabry-Perot type microcavity. Nevertheless, we show that a large amount of light is emitted into the guided modes of the planar stack reducing the optical confinement which is likely to be reached within this type of dielectric microcavities.

Spontaneous emission of rare-earth ions confined in planar multilayer dielectric microcavities

Using the “memory effect”, we propose and implement a broadband, compact, and cost-effective Wavefront Sensing scheme with a simple thin diffuser. We experimentally demonstrate its capability to provide quantitative phase imaging and nanoparticle superlocalization.

Wavefront Sensing with a Thin Diffuser: Application to super-localization

In addition to their interesting capabilities for bio-imaging, nonlinear optical contrasts involve rich excitation/emission processes based on multiple fields and therefore multiple polarization directions coupling. This opens the way to analysis of high order symmetry features in bio-molecular assemblies down to the nanometric scale, that are not accessible by linear optics tools [1]. We have recently developed a general polarimetric nonlinear microscopy technique able to circumvent the intrinsic limitations of fluorescence anisotropy, which is today the most widely used technique to measure molecular order information in biological samples. This polarimetric method, based on a variation of the incident fields polarization states combined with a polarized read-out of the emitted signal, allows retrieving information on local molecular angular distribution with no necessary a priori knowledge on its averaged orientation nor its shape. We will demonstrate on several examples how this polarization-dependent nonlinear microscopy technique is able to measure quantitatively molecular order information in biological samples. Different contrasts will be described with emphasis on their specificities, either for incoherent processes such as multiphoton fluorescence or for coherent harmonic generations. These specificities are illustrated in crystalline samples, cells and tissues, where the contrasts are provided either from membrane markers (two-photon fluorescence) [2], from intrinsic mechanisms such as second harmonic generation (SHG) [3] or vibrational signatures using Coherent Anti Stokes Raman Scattering (CARS) [4]. Instrumental issues will be discussed, in particular on the diagnostics of polarization distortions due to complex samples such as tissues [3], or inherent to polarization-resolved microscopy [5].

Hervé Rigneault

Papers

Interpreting anisotropy and disturbances of optical properties of thin films in terms of layer microstructure

Spontaneous emission of rare-earth ions confined in planar multilayer dielectric microcavities

Wavefront Sensing with a Thin Diffuser: Application to super-localization

Quantifying molecular order in biological samples using polarimetric muti-modal nonlinear microscopy

Optical Waveguide Characterization of Thin Films (光学薄膜特集号)