Author
Juan José Sáenz
Other affiliations: Ikerbasque, Autonomous University of Madrid, Autonomous University of Barcelona ...read more
Bio: Juan José Sáenz is an academic researcher from Donostia International Physics Center. The author has contributed to research in topics: Scattering & Dielectric. The author has an hindex of 48, co-authored 248 publications receiving 9402 citations. Previous affiliations of Juan José Sáenz include Ikerbasque & Autonomous University of Madrid.
Topics: Scattering, Dielectric, Light scattering, Dipole, Conductance
Papers published on a yearly basis
Papers
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TL;DR: This work finds that Silicon particles with index of refraction∼3.5 and radius∼200 nm present strong electric and magnetic dipolar resonances in telecom and near-infrared frequencies, without spectral overlap with quadrupolar and higher order resonances.
Abstract: High-permittivity dielectric particles with resonant magnetic properties are being explored as constitutive elements of new metamaterials and devices. Magnetic properties of low-loss dielectric nanoparticles in the visible or infrared are not expected due to intrinsic low refractive index of optical media in these regimes. Here we analyze the dipolar electric and magnetic response of lossless dielectric spheres made of moderate permittivity materials. For low material refractive index (≲ 3) there are no sharp resonances due to strong overlapping between different multipole contributions. However, we find that Silicon particles with index of refraction ∼ 3.5 and radius ∼ 200nm present strong electric and magnetic dipolar resonances in telecom and near-infrared frequencies, (i.e. at wavelengths ≈ 1.2 – 2μm) without spectral overlap with quadrupolar and higher order resonances. The light scattered by these Si particles can then be perfectly described by dipolar electric and magnetic fields.
649 citations
TL;DR: Experimental evidence is presented that a single low-loss dielectric subwavelength sphere of moderate refractive index radiates fields identical to those from equal amplitude crossed electric and magnetic dipoles, and indistinguishable from those of ideal magnetodielectric spheres, and these Kerker scattering conditions only depend on a/λ.
Abstract: Magnetodielectric small spheres present unusual electromagnetic scattering features, theoretically predicted a few decades ago. However, achieving such behaviour has remained elusive, due to the non-magnetic character of natural optical materials or the difficulty in obtaining low-loss highly permeable magnetic materials in the gigahertz regime. Here we present unambiguous experimental evidence that a single low-loss dielectric subwavelength sphere of moderate refractive index (n=4 like some semiconductors at near-infrared) radiates fields identical to those from equal amplitude crossed electric and magnetic dipoles, and indistinguishable from those of ideal magnetodielectric spheres. The measured scattering radiation patterns and degree of linear polarization (3–9 GHz/33–100 mm range) show that, by appropriately tuning the a/λ ratio, zero-backward (‘Huygens’ source) or almost zero-forward (‘Huygens’ reflector) radiated power can be obtained. These Kerker scattering conditions only depend on a/λ. Our results open new technological challenges from nano- and micro-photonics to science and engineering of antennas, metamaterials and electromagnetic devices. The absence of forward or backward scattered radiation by magnetodielectric spheres was predicted decades ago, yet direct measurements have remained elusive. Geffrin et al. present unambiguous evidence of such scattering effects in the gigahertz range for a sub-wavelength dielectric sphere.
539 citations
TL;DR: The first experimental demonstration of zero backscattering from nanoparticles at optical frequencies as originally discussed is presented, agreeing with calculations based on the discrete dipole approximation.
Abstract: We present the first experimental demonstration of zero backscattering from nanoparticles at optical frequencies as originally discussed by Kerker et al. [ Kerker , M. ; Wang , D. ; Giles , C. J. Opt. Soc. A 1983 , 73 , 765 ]. GaAs pillars were fabricated on a fused silica substrate and the spectrum of the backscattered radiation was measured in the wavelength range 600-1000 nm. Suppression of backscattering occurred at ~725 nm, agreeing with calculations based on the discrete dipole approximation. Particles with zero backscattering provide new functionality for metamaterials and optical antennas.
484 citations
TL;DR: The first experimental demonstration of zero backscattering from nanoparticles at op- tical frequencies was presented by Kerker et al. as discussed by the authors, where GaAs pillars were fabricated on a fused silica substrate and the spectrum of the backscattered radiation was measured in the wavelength range 600-1000 nm.
Abstract: We present the first experimental demonstration of zero backscattering from nanoparticles at op- tical frequencies as originally discussed by Kerker et. al. [M. Kerker, D. Wang, and C. Giles, J. Opt. Soc. A 73, 765 (1983)]. GaAs pillars were fabricated on a fused silica substrate and the spectrum of the backscattered radiation was measured in the wavelength range 600-1000 nm. Suppression of backscattering occurred at ~725 nm, agreeing with calculations based on the discrete dipole approximation. Particles with zero backscattering provide new functionality for metamaterials and optical antennas.
366 citations
TL;DR: In this article, the electromagnetic behavior of the basic unit constituted by a dimer of dielectric nanoparticles made of moderately low-loss high refractive index material is explored and studied through an analytical dipole-dipole model.
Abstract: Dielectric nanoparticles with moderately high refractive index and very low absorption (like Si and Ge in the visible–near-infrared (VIS–NIR) range) show a magnetodielectric behavior that produces interesting far-field coherent effects, like directionality phenomena or field enhancement in the proximity of the particle surface. As in the case of metals, ensembles of two or more dielectric particles can constitute basic elements for developing new spectroscopic tools based on surface field enhancement effects. Here we explore the electromagnetic behavior of the basic unit constituted by a dimer of dielectric nanoparticles made of moderately low-loss high refractive index material. The interactions responsible for the spectral features of the scattered radiation and field enhancement of the dimer are identified and studied through an analytical dipole–dipole model. The fluorescence of a single emitter (either electric or magnetic dipole) located in the dimer gap is also explored by calculating the quantum e...
360 citations
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28 Jul 2005
TL;DR: PfPMP1）与感染红细胞、树突状组胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作�ly.
Abstract: 抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。
18,940 citations
Book•
15 May 2007
TL;DR: In this paper, the authors discuss the role of surface plasmon polaritons at metal/insulator interfaces and their application in the propagation of surfaceplasmon waveguides.
Abstract: 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.
7,238 citations
TL;DR: The most relevant features of WSXM, a freeware scanning probe microscopy software based on MS-Windows, are described and some relevant procedures of the software are carried out.
Abstract: In this work we briefly describe the most relevant features of WSXM, a freeware scanning probe microscopy software based on MS-Windows. The article is structured in three different sections: The introduction is a perspective on the importance of software on scanning probe microscopy. The second section is devoted to describe the general structure of the application; in this section the capabilities of WSXM to read third party files are stressed. Finally, a detailed discussion of some relevant procedures of the software is carried out.
6,996 citations
TL;DR: The atomic force microscope (AFM) is not only used to image the topography of solid surfaces at high resolution but also to measure force-versus-distance curves as discussed by the authors, which provide valuable information on local material properties such as elasticity, hardness, Hamaker constant, adhesion and surface charge densities.
3,281 citations
TL;DR: How high-index dielectric nanoparticles can offer a substitute for plasmonic nanoparticle structures, providing a highly flexible and low-loss route to the manipulation of light at the nanoscale is reviewed.
Abstract: The resonant modes of plasmonic nanoparticle structures made of gold or silver endow them with an ability to manipulate light at the nanoscale. However, owing to the high light losses caused by metals at optical wavelengths, only a small fraction of plasmonics applications have been realized. Kuznetsov et al. review how high-index dielectric nanoparticles can offer a substitute for these metals, providing a highly flexible and low-loss route to the manipulation of light at the nanoscale.
Science , this issue p. [10.1126/science.aag2472][1]
[1]: /lookup/doi/10.1126/science.aag2472
2,161 citations