Nanofotónica y Metamateriales en el IEM José A. Sánchez Gil...IEM Ins$tuto de Estructura de la...

IEM Ins$tutodeEstructuradelaMateria

NanofotónicayMetamaterialesenelIEM

JoséA.SánchezGil


Dpto.EspectroscopíaNuclear,VibracionalydeMediosDesordenados

EspectroscopíasdeSuperficieyFotónicadePlasmonesSuperficialesJoseA.SánchezGil&DiegoRomeroAbujetas

LuisS.Froufe-PérezRamónPaniagua


¿Quéeslananofotónica?

Cabezadealfiler:~1mm=1.000.000nmGlóbulorojo:~7-8micras=7000-8000nmVirus:24–300nmMoléculadeagua:~0.275nm

1m=1.000.000.000nm LUZ


¿Quéeslananofotónica?ELECTROMAGNETISMO+MATERIACONDENSADA:

PROPAGACIÓN,CONFINAMIENTOEINTERACCIÓNRADIACIÓN-MATERIAENESCALASPORDEBAJODELALONG.DEONDA(λ)


Fenomenología de interés en Nanofotónica

•  PlasmonesSuperficialesLocalizados•  Metamateriales•  LuzMagné$caendieléctricosdealtoíndice•  Nanohilossemiconductores:Fotoluminiscenciayabsorción


METALESENELVISIBLE

TeoríadeDrudeparametales:elmodelodeelectroneslibres

¡SOLUCIONESCONFINADASENLAFRONTERAMETAL-DIELÉCTRICO!

PLASMONESSUPERFICIALES


PLASMONESSUPERFICIALESLOCALIZADOS(LOCALIZEDSURFACEPLASMONRESONANCES)

ELECTROSTÁTICATEORÍADEG.MIE(1908)


¿PORQUÉNOSINTERESANLOSPLASMONES?

•  Sonmuysensiblesaloque$enenalrededoroseencuentranporelcamino:-deteccióndemoléculasaisladas-estudionodestruc$vosdemuestras•  Propiedadesdeconfinamientodelaluzydistanciasdepropagación(ondasquasi-2D),buenoscandidatosparatransmisióndeinformación.

SURFACEPLASMONPOLARITONS LOCALIZEDSURFACEPLASMONS

•  Producengrandesintensificacionesdelcampo:

-aplicaciónenespectroscopías(SERS)•  Producengrandesmodificacionesdela

densidadlocaldeestados:-modificacióndelosprocesosdeemisióndeluz(inhibiciónointensificación)•  Radiandeunamaneracontrolada:-nanoantenna


APLICACIONES

SURFACEPLASMONPOLARITONS

LOCALIZEDSURFACEPLASMONS


ENTONCES…¿QUÉHACEMOSNOSOTROS,EXACTAMENTE?

•  Estudiamoscómosecomportalaluzalinteractuarconunobjeto(nanométrico)

•  Estudiamosquédiseñoeselmasadecuadoparaunpropósitoconcreto.

y…¿CÓMOLOHACEMOS?

•  ¡Esmuysencillo!

escribimoslasecuacionesquedescribenlatsicadelsistemay,generalmente:


Porejemplo,elsca$eringdeluzpornano-objetos:

Ecs.IntegralesdeSuperficie

EDP’s GeometríaDiferencial VariableCompleja

EcuacionesIntegrales FuncionesEspeciales

CÁLCULONUMÉRICO

min

max


Giannini,R

odrig

uez-Oliveros

&Sánchez-Gil,Plasm

onics(201

0)

Gianninieta

l,JOSA

A(2

007)

Rodriguez-Oliveros&Sánchez-Gil,Opt.Express(2011)


Rodríguez-Oliveros&Sánchez-Gil,Opt.Express(2012)


López-Tejeiraetal.NewJ.Phys.(2012) López-Tejeira,Paniagua-Domínguez&Sánchez-Gil,ACSNano(2012)

DELOTEÓRICO… …ALOAPLICADO


¿Quésonlosmetamateriales?

L

L << λ


“Jugandoconlaspiezas”podemosobtener……cualquiervalordeRe(εeff)ydeRe(µeff)!!!

Re(ε)

Re(µ)

Re(ε)>0Re(ε)<0

Re(ε)<0 Re(ε)>0

Re(µ)>0Re(µ)>0

Re(µ)<0 Re(µ)<0

DIELÉCTRICOMETAL

PLASMAMAGNÉTICO

¿?

Metamateriales“zurdos”


Refracciónnega$va

Re(ε)>0Re(µ)>0

Re(ε)<0Re(µ)<0


SRR M-W

Re(ε)<0Re(µ)<0

•Problemasdediseño:escaladohaciaelvisible,anchodebanda,disipación,isotropía,…•Problemasfundamentales:¿cómocalcularlaspropiedadesefec$vasdeunsistemadado?¿cómogaran$zarquetengansen$dotsico?¿misistemaesrealmentehomogéneo?¿quéocurreenlasintercaras?¿cómotratamosladispersiónespacial,elacoplamientomagnetoeléctricoolosgapsfotónicos?¿cómoop$mizarundiseñodecaraalaaplicación?


Metamateriales“zurdos”eisótroposenelóp$co,basadosennanoestructurascore-shell

R.Paniagua-Domínguezetal.,New.J.Phys.(2011)R.Paniagua-Domínguezetal.,Scien>ficReports(2013)

Núcleo metálico: Recubrimiento dieléctrico: Plasmon localizado Resonancia (Luz) Magnética


R.Paniagua-Domínguezetal.,New.J.Phys.(2011) Abujetasetal.,J.Opt.(2015) ,Sci.Reports(2013)

EkH

Routa Rin

ΓM ΓK

EkH

SiAg

Negative Refraction Flat lensing

Dipole pyDipole px|P|(TW/m2)0 50

ν = 235 THz λ = 1.28 µm


Modos guíados Resonancias Mie

Emisión (PL) Absorción

��

��

�

�

�

��

�

��

��

�

��

��

Nanohilos Semiconductores

Luz confinada en la nanoescala


Semiconductor NW Photoluminescence/Absorption

•  Enhanced/Direc$onalPLInPNWs:Fouriermicroscopy(Grzelaetal,NanoLe~.2012)

vanDametal,NanoLe~.2015)

•  Enhanced/Direc$onalPL:Analy$calmodel(Paniaguaetal,Nanoscale2013)

•  Enhanced/Direc$onalAbsorp$on:MieresonancesvsLeakymodes(Grzegorzetal,NanoLe~.2014,ACSPhoton.2015)

IEM Ins$tutodeEstructuradelaMateria Nanofotónica

NW (PL) Antenna Emission

Hybrid (core-shell)

Metal Semiconductor

Nanorod Fano LSP

Metamaterials NIMs


Paramásinformación:JoséA.Sá[email protected],2ªPlanta.Extensión942219

Ultra low-loss, isotropic opticalnegative-index metamaterial based onhybrid metal-semiconductor nanowiresR. Paniagua-Domınguez, D. R. Abujetas & J. A. Sanchez-Gil

Instituto de Estructura de la Materia, Consejo Superior de Investigaciones Cientıficas, Serrano 121, 28006 Madrid, Spain.

Recently, many fascinating properties predicted for metamaterials (negative refraction, superlensing,electromagnetic cloaking,…) were experimentally demonstrated. Unfortunately, the best achievementshave no direct translation to the optical domain, without being burdened by technological and conceptualdifficulties. Of particular importance within the realm of optical negative-index metamaterials (NIM), is theissue of simultaneously achieving strong electric and magnetic responses and low associated losses. Here,hybrid metal-semiconductor nanowires are proposed as building blocks of optical NIMs. The metamaterialthus obtained, highly isotropic in the plane normal to the nanowires, presents a negative index of refractionin the near-infrared, with values of the real part well below 21, and extremely low losses (an order ofmagnitude better than present optical NIMs). Tunability of the system allows to select the operating range inthe whole telecom spectrum. The design is proven in configurations such as prisms and slabs, directlyobserving negative refraction.

The so called metamaterials are artificial materials in which the effective medium properties, usually exoticand not naturally attainable, depend on the geometry of their basic constituents, rather than on theirchemical composition1,2. Ranging from sub-diffraction resolution3,4 or spontaneous emission5 to extreme

control over the flow of light6,7, many exciting and unexpected phenomena have been achieved or predicted forthis new kind of materials. Although originally developed in electromagnetics, many of the ideas developed in thisfield have been successively extended or adapted to other ondulatory phenomena, such as acoustics, making it oneof the most active in the engineering and physical sciences in the past few years.

Still, however, there are many open challenges in the field. Among them, the realization of a bulk isotropicnegative index metamaterial (NIM), with negative refraction and low losses in the optical domain8,9. In generalterms, the major issue when trying to achieve such a goal is obtaining a strong diamagnetic response of theconstituents, enough to lead to an effective negative permeability. Probably as a consequence of the success of theoriginal designs operating in the microwave regime, many efforts were made to adapt them to increasingly higherfrequencies, mainly by miniaturization8,9. Apart from some inherited from the original designs, such as aniso-tropy, many drawbacks were found in doing so, mainly related to the different behaviour of metals at opticalfrequencies, such as saturation of the magnetic response10 or high losses associated to ohmic currents. As aconsequence, completely different strategies were studied to obtain artificial magnetism11,12, as those based indisplacement currents appearing in nanoparticle clusters due to coupling between structures13. However, some ofthe most successful were those which attempted to obtain it from natural magnetic resonant modes in highpermittivity dielectrics, leading to low-loss magnetic materials14–18. Secondary structures or particular arrange-ments were needed to provide the additional electrical response, necessary to obtain doubly negative index ofrefraction19–21. Thus far, the maximum theoretical figure of merit (f.o.m 5 2Re(neff)/Im(neff)) reported is of theorder of f.o.m., 2522–24 for metamaterials based on canonical fishnet designs; their dimensions, however, are inthe very limit of validity of the effective medium description, and isotropy was not proven (see25 for a review onthis topic).

In this work, we propose a structure that, combining electric and magnetic responses, can be used as the basicbuilding block for extremely low-loss (f.o.m., 200) isotropic two-dimensional metamaterials in the near-infra-red, with simultaneously negative permittivity ( ) and permeability (m) at optical frequencies. Such structure is acore-shell nanowire (NW) of circular cross section. Noble metals such as silver or gold can be employed to buildthe core, and high permittivity semiconductors, such as silicon or germanium, to build the shell. Artificialmagnetism of the effective medium is achieved by exciting the lowest order Mie-like magnetic resonance in

SUBJECT AREAS:METAMATERIALS

NANOWIRES

SUB-WAVELENGTH OPTICS

NANOPHOTONICS ANDPLASMONICS

Received

1 February 2013

Accepted

6 March 2013

Published

21 March 2013

Correspondence andrequests for materials

should be addressed toJ.A.S.-G. (j.sanchez@

csic.es)

SCIENTIFIC REPORTS | 3 : 1507 | DOI: 10.1038/srep01507 1

1 Mode Parity-Controlled Fano- and Lorentz-like Line Shapes Arising in2 Plasmonic Nanorods3 Niels Verellen,*,†,‡ Fernando Lopez-Tejeira,§ Ramon Paniagua-Domínguez,∥ Dries Vercruysse,‡,†

4 Denitza Denkova,† Liesbet Lagae,‡,† Pol Van Dorpe,‡,† Victor V. Moshchalkov,† and Jose A. Sanchez-Gil∥

5†INPAC and Department of Physics and Astronomy, KU Leuven, Celestijnenlaan 200 D, B-3001 Leuven, Belgium

6‡IMEC, Kapeldreef 75, B-3001 Leuven, Belgium

7§Departamento de Física de la Materia Condensada, Escuela de Ingeniería y Arquitectura, Universidad de Zaragoza, María de Luna 3,

8 E-50018 Zaragoza, Spain9∥Instituto de Estructura de la Materia (IEM-CSIC), Consejo Superior de Investigaciones Científicas, Serrano 121, E-28006 Madrid,

10 Spain

11 *S Supporting Information

12 ABSTRACT: We present the experimental observation of spectral13 lines of distinctly different shapes in the optical extinction cross-section14 of metallic nanorod antennas under near-normal plane wave15 illumination. Surface plasmon resonances of odd mode parity present16 Fano interference in the scattering cross-section, resulting in17 asymmetric spectral lines. Contrarily, modes with even parity appear18 as symmetric Lorentzian lines. Finite element simulations are used to19 verify the experimental results. The emergence of either constructive or20 destructive mode interference is explained with a semianalytical 1D line21 current model. This simple model directly explains the mode-parity22 dependence of the Fano-like interference. Plasmonic nanorods are23 widely used as half-wave optical dipole antennas. Our findings offer a24 perspective and theoretical framework for operating these antennas at25 higher-order modes.26 KEYWORDS: Nanoantenna, surface plasmon resonance, Fano resonance, interference, plasmonics

27Metallic nanorods are exploited as biological imaging28 probes and widely used as generic plasmonic dipole29 antennas operating at optical and near-infrared frequencies,30 forming an analogue to classical half-wave dipole antennas.31 Nanorod antennas are an excellent tool for the manipulation of32 a variety of nanoscale light−matter interactions.1,2 They form33 the building blocks for Yagi-Uda antennas which allow34 directional control of light,3−6 or they can act as active optical35 antennas for photodetection by generating hot electrons.7

36 Recently, it was demonstrated how plasmonic nanorods can be37 used to efficiently convert the radiation of quantum emitters38 into novel multipolar sources of photons owing to the higher-39 order localized surface plasmon resonances (LSPRs) supported40 by these antennas.8,9

41 The fundamental dipole and higher-order antenna modes42 have been extensively studied experimentally using optical43 spectroscopy10−15 and a broad range of mapping techniques44 based on, for example, scanning near-field microscopy,16−19

45 two-photon induced luminescence (TPL),20 cathodolumines-46 cence,21 multiphoton absorption in photosensitive polymers,22

47 electron energy loss spectroscopy (EELS),23 and photocurrent48 mapping.24 Likewise, theoretical investigations have elucidated49 the antenna modes’ scaling properties and their dependence on

50the shape, size, and dielectric environment by using a variety of51methods.12,13,25−27 Despite this large interest in nanorods, only52very few reportsall theoreticaladdress the scattering53behavior with a focus on the spectral line shape.28−30

54Plasmon resonance, as a wave phenomenon, is expected to55present interference characteristics. The wave nature of56propagating surface plasmon polaritons (SPPs) was elegantly57demonstrated with a Young’s double slit experiment.31 For58localized surface plasmon resonances, the interference of59spectrally overlapping and coupled modes is well-recognized60to affect the scattering behavior of the nanostructure under61investigation.32,33 In particular, the interference of a broad62background continuum state with spectrally sharp higher-order63 f1resonances, as schematically illustrated in Figure 1a, can lead to64a spectral response with asymmetric Fano-like line shapes in a65variety of nanoparticle configurations such as nanosphere66clusters,34 asymmetric dolmen-like nanorod arrangements,35,36

67disk-ring arrangements,37,38 nanocrosses,39,40 and others.32,41

68Fano resonances can also be substrate-induced in nanorods

Received: December 17, 2013Revised: March 28, 2014

Letter

pubs.acs.org/NanoLett

© XXXX American Chemical Society A dx.doi.org/10.1021/nl404670x | Nano Lett. XXXX, XXX, XXX−XXX

amc00 | ACSJCA | JCA10.0.1465/W Unicode | research.3f (R3.6.i5 HF01:4227 | 2.0 alpha 39) 2014/03/19 08:04:00 | PROD-JCAVA | rq_3379248 | 4/07/2014 14:24:27 | 8 | JCA-DEFAULT

Directional and Polarized Emission from Nanowire ArraysDick van Dam,*,† Diego R. Abujetas,‡ Ramon Paniagua-Domínguez,‡ Jose A. Sanchez-Gil,‡Erik P. A. M. Bakkers,†,§ Jos E. M. Haverkort,† and Jaime Gomez Rivas*,†,∥

†Department of Applied Physics, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The Netherlands‡Instituto de Estructura de la Materia (IEM-CSIC), Consejo Superior de Investigaciones Científicas, Serrano 121, 28006, Madrid,Spain§Kavli Institute of Nanoscience, Quantum Transport, Delft University of Technology, 2600 GA Delft, The Netherlands∥FOM Institute AMOLF, c/o Philips Research, High-Tech Campus 4, 5656 AE Eindhoven, The Netherlands

*S Supporting Information

ABSTRACT: Lighting applications require directional andpolarization control of the emitted light, which is currentlyachieved by bulky optical components such as lenses, parabolicmirrors, and polarizers. Ideally, this control would be achievedwithout any external optics, but at the nanoscale, during thegeneration of light. Semiconductor nanowires are promisingcandidates for lighting devices due to their efficient lightoutcoupling and synthesis flexibility. In this work, wedemonstrate a precise control of both the directionality andthe polarization of the nanowire array emission by changingthe nanowire diameter. We change the angular emissionpattern from a large-angle doughnut shape to a narrow-angle beaming along the nanowire axis. In addition, we tune thepolarization from unpolarized to either p- or s-polarized. Both the far-field emission pattern and its polarization are controlled bythe number and type of guided or leaky modes supported by the nanowire, which are determined by the nanowire diameter.KEYWORDS: Nanowires, Fourier microscopy, polarization, emission, directionality

Controlling the polarization and directionality of theemission of nanosized light sources is of great importance

in the engineering of light-emitting diodes (LEDs),1−4

nanolasers,5,6 and applications in quantum optics such as singlephoton sources.7−10 The bottom-up growth of semiconductornanowires (NWs) allows a large design flexibility in parameterssuch as nanowire position, size, interwire distance, andcrystallographic orientation. This makes nanowires interestingcandidates for the design of nanosized light emitters anddetectors.11

Wide-range control over the direction of the nanowireemission has not yet been reported. Previous studies haveindicated the two main mechanisms that affect the nanowireemission directionality.12−14 Recently, the directional emissionof thin InP nanowires has been explained by coupling to leakywaveguide modes in the nanowire.15 These modes modify thedirection of the nanowire emission, causing an antenna-likebehavior.7,15,16 Identification of the relevant guided/leakynanowire modes is important in tuning the direction of thefar field emission.17 The second mechanism that was associatedwith the emission directionality of NW arrays is the coupling ofthe emission to resonances in periodic arrays of nanowires,which behave as quasi-two-dimensional photonic crystals. Thephotoluminescence excited in one of the nanowires may coupleto Bloch modes supported by the periodic structure and coupleout to free space in certain directions. This directional

outcoupling has been theoretically18 and experimentallydemonstrated.14,19 So far, no studyeither theoretically orexperimentallyof the interplay of both described mechanismshas been reported.In addition to directionality, control over the emission

polarization is important for many applications, such as solid-state lighting, sensing, and optical communication. Thinnanowires have the ability to emit strongly polarizedlight,20,21 which is a useful property for displays and sensing2

but may hinder the application in quantum optics.22 Thenanowire polarization anisotropy has been first explained in theelectrostatic limit by the elongated shape of the nanowires andthe high refractive index contrast with the environment,20 and ithas later been described in terms of coupling to Mieresonances.22 On top of that, the selection rules of the bandstructure of the emitting material also affect the polarization.21

However, it is unknown how the polarization of the nanowireemission depends on the diameter, taking into account bothwaveguide modes and selection rules.In this Letter we discuss the polarized and directional

emission properties of semiconductor nanowire arrays, which

Received: March 23, 2015Revised: May 21, 2015Published: June 4, 2015

Letter

pubs.acs.org/NanoLett

© 2015 American Chemical Society 4557 DOI: 10.1021/acs.nanolett.5b01135Nano Lett. 2015, 15, 4557−4563

Nanofotónica y Metamateriales en el IEM José A. Sánchez Gil...IEM Ins$tuto de Estructura de la...

Documents

Transcript of Nanofotónica y Metamateriales en el IEM José A. Sánchez Gil...IEM Ins$tuto de Estructura de la...