Metamaterials

MetamatirialsUn

Metamaterials (MMs) constitute the frontier in material science technology. Unlike classic natural materials,  MMs optical properties can be easily tailored as desired by suitably arranging the geometry, shape or size of their fundamental constituents. MMs are usually made of deeply subwavelength metal/dielectric building blocks arranged in periodic patterns showing one, two or three dimensional symmetry, possibly embedding reconfigurable and/or gain material in order to provide them smart responsive properties. Our research is focused upon two main branches: Hyperbolic Metamaterials and Chiral Metamaterials. Thanks to their extreme optical parameters, they both offer unprecedented design flexibility and open to a plethora of fascinating new properties in photonics, plasmonics, nanotechnology and bio-nano science fields.

 

Hyperbolic Metamaterials

 

HyperbolicMaterials

Hyperbolic Metamaterials are artificial nanostructures featuring extreme optical anisotropy. With respect to the in plane (εx= εy = ε||) and out of plane (εy = εperp) dielectric permittivities, four anisotropies can be identified, two of which imply the sign of ε|| and εperp to be opposite. In these cases the HMM can behave as an effective dielectric for an in-plane polarized lightwave and, at the same time, as a metal for an out-of-plane one (Type I anisotropy, ε|| > 0 and εperp < 0), or completely inverse (Type II anisotropy, ε|| < 0 and εperp > 0). Two main geometries are considered to behave in this way: (1) deeply subwavelength array of metallic nanowires, embedded in a dielectric matrix and (2) 1D metal/dielectric periodic multilayers. In the latter case (the easiest to fabricate), the design of the optical parameters of the overall HMM can be easily carried out in the framework of the Effective Medium Theory, simply by acting on the thickness of the fundamental materials and on their fill fraction. This way, the refractive index of such materials can be tailored as desired in order to unlock many fascinating exotic behaviors, such as ultra-subwavelength light collimation, perfect lensing and so on. Our research consists both in exploring new frontiers in the exciting field of HMMs (mainly investigating about new conception fundamental materials and/or periodic arrangements) and designing and developing HMM based devices such as perfect lenses, biosensors, HMM based photovoltaic modules and HMM based nanolasers.

Highlights:

Tunable Epsilon Near Zero and Pole (ENZP)HMM (Perfect Lens and Supercollimator)

  1. A. Ramakrishna et. al. demonstrated the possibility of using extremely anisotropic media, such as hyperbolic metamaterials (HMMs), to reach the so called “canalization regime”, a condition we renamed εNZP under which the medium shows εx = εy = 0 (in the plane) and εz = simultaneously.

The iso-frequency surface for the extraordinary (TM-polarized) waves propagating in such an HMM is given by

Formula

Where: Formula2 and Formula3

Here εm and εd are the permittivities of the two materials chosen as building blocks (m for metal and d for dielectric). The simultaneous condition of ε ~ 0 and ε ~ ∞ can be fulfilled if Ld = Lm and, contemporarily, εm = – εd.
We demonstrated the experimental realization and characterization of a particular HMM showing the aforementioned condition (εNZP), in the visible range, opening the way to extreme applications as supercollimation effect and perfect lens behavior for high resolution bio-imaging.

 

bio-imaging

 

HMM based applications (Improved transmission, emission rate enhancement and nanolasers)

A two-dimensional (2D) silver diffraction grating coupled with an Ag/Al2O3 HMM shows 18-fold spontaneous emission decay rate enhancement of dye molecules with respect to the same HMM without grating. The experimental results are compared with analytical models and numerical simulations, which confirm that the observed enhancement of grating-coupled HMM (GCHMM) is due to the outcoupling of non-radiative plasmonic modes as well as strong plasmon-exciton coupling in HMM via diffracting grating.

 

HMM

 

Chiral metamaterials

 

Twisted

Chiral metamaterials are a new class of metamaterials where a specific chiral geometry induces an optical response to the incident light field resulting from a mixture of electric and magnetic dipoles. This leads to many intriguing phenomena and applications, such as strong circular dichroism or optical rotatory dispersion, and provides interesting potential applications as broadband circular polarizers or to enhance the optical response of chiral molecules by superchiral light, offering also a simpler route to negative refraction. In particular, three-dimensional nanoscale geometries provide a wider set of functionalities, as broadband chirality to manipulate circular polarization at optical frequencies, but their fabrication becomes challenging as their dimensions get smaller. Our objective is to study the optical response of these nanostructures towards the development of miniaturized optical components such as circular polarizers, beam splitters, optical insulators, or for the dichroic spectroscopy of biological molecules.

Highlights:

3D Chiral Metamaterials in the VIS range

Plasmonic nanohelices have been realized by a bottom-up fabrication approach based on focused ion and electron beam induced deposition, providing a nanometer scale control on geometrical features. The fabricated arrays show chiro-optical properties at the optical frequencies and extremely high operation bandwidth tailoring dependent on the dimensional features.

TwistedMulti

Highly Pure Broadband Circular Polarizers based on Intertwined Fully 3D Nanostructures

Three dimensional triple-helical nanowires have been engineered by the innovative tomographic rotatory growth, on the basis of focused ion beam-induced deposition. These three dimensional nanostructures show large circular dichroism between 500 and 1000 nm, with a high signal-to-noise ratio. Optical activity of up to 8 only due to the circular birefringence is also shown, tracing the way towards chiral photonic devices that can be integrated in optical nanocircuits to modulate the visible light polarization.

MetamatirialsUn

Optical Metamaterials

Optical Hyperbolic Metamaterials

Metamaterials are a class of artificial materials having structural parameters much smaller than the operative wavelength, usually nanostructured for optical frequencies. Nonetheless, their effective response to ligthwaves shows extraordinary and fascinating properties. Many promising physical behaviours can arise from materials with such unusual electromagnetic response, among which negative refraction, optical cloacking, super resolution imaging, ultra compact optical circuits, plasmonic nanolasers, inversion of the Cherenkov radiation are only few examples. Recently, a new branch of the metamaterial class is receiving an increasing attention in the scientific panorama, which holds an ultra anisotropic behavior not yet found in nature for optical frequencies. These materials are known as hyperbolic metamaterials (HMMs), possessing an extraordinary high anisotropy in the dielectric properties. Due to this extreme anisotropy they represent the way to realize effective bulk meta-structure with particular optical properties in the visible range.

Metal-dielectric multilayers and nanowire arrays with hyperbolic dispersion have been realized across the visible range and various interesting effects have been demonstrated, including subwavelength imaging. By properly mixing a metal with a special dielectric as building blocks, epsilonperp and epsilonpar of the entire system can become either positive or negative, opening the way to an extreme anisotropy. Sputtering and thermal deposition techniques are used in order to obtain multilayer structures with nanometric thickness of the single unit cell. Extraordinary properties have been found.

Gain-assisted Metamaterials

Metamaterials, being based on metal sub-units, suffer from the high values of ohmic losses, that prevent their use in real applications. The idea to bring gain molecules in close proximity to metallo-dielectric nanostructures is based on coherent effects of excitation energy transfer between resonant bands of the two materials. It is well known that relevant modifications of the fluorescence of dye molecules placed in close proximity to metal NPs are due to mutual interactions with NPs surface plasmons, including resonant energy transfer (RET).

Approaches at meso- and macro- scales have been proposed to fill the gap between the single plasmonic nanostructure and bulk materials. Different systems have been realized at various scale and by following different chemical techniques. At these scales, the plasmon-gain interplay is dominated by the location of the gain medium with respect to the spatial distribution of the local field.

Fabrication of functional nanoparticles and nanostructures

Nano-composite and nano-structured materials feature special physical properties, at the base of innovative technologies. Therefore the fabrication research line is paramount for the different research activities carried out @Nanotec-CS, namely Optical metamaterials, Biosensing, Optofluidics, Plasmonics. The deployed fabrication techniques encompasses both top-down and bottom-up approaches, taking advantage from hybrid strategies.

A new generation of nanostructured plasmonic materials, created for infrared and optical frequencies, can be prepared by the use of nano-chemistry and self-assembly of soft materials as an alternative to standard lithography or multi-beam holography. Nano-scale chemistry offers today a tremendous versatility in terms of constituent materials, morphologies, sizes and surface functions of achievable nano-particles that will constitute the fundamental building blocks of the nano-structured composites. This approach is typically bottom-up, and it can be integrated with top-down techniques, as the traditional UV-mask lithography, or with Multi-photon Direct Laser Writing (DLW) in soft materials. We aim to fabricate arbitrarily complex 3D hybrid structures metallic/dielectric with features in the 100 nm range

In parallel, studies on special resists doped with metallic precursors, to be used for 2-photons DLW are carried out, for creating metallic NPs inside polymeric structures.

Gold nanoparticles in pva MATRIX

Facilities & Labs

Photonics Lab @ Lecce

Nanofab Lab @ Lecce

Beyon Nano @ Rende

People

espositomarcoMarco

Esposito

Associate PostDoc

passaseoAdriana

Passaseo

CNR Senior Researcher

VittoriannaTascoVittorianna

Tasco

CNR Researcher

massimo_cuscunaMassimo

Cuscunà

CNR Technologist

Roberto_bartolinoRoberto

Bartolino

Associate Professor

versaceCarlo C.

Versace

Associate Professor

Francesco_TodiscoFrancesco

Todisco

Associate PostDoc

Iolena_tarantiniIolena

Tarantini

Associate Technician

milen_degiorgiMilena

De Giorgi

CNR Technologist

Marco

Leonetti

CNR Research Fellow

daniele_sanvittoDaniele

Sanvitto

CNR Senior Researcher

Massimo_LaDedaMassimo

La Dedda

Associate Professor

Antonio_deLucaAntonio

De Luca

Associate Professor

Giuseppe-StrangiGiuseppe

Strangi

CNR Research

michel giocondoMichele

Giocondo

CNR Researcher

termineRoberto

Termine

CNR Researcher

vincenzo-caligiuriVincenzo

Caligiuri

Associate PhD Student

Publications

  1. V. Caligiuri, A. De Luca, Metal-semiconductor-oxide extreme hyperbolic metamaterials for selectable canalization wavelength, Journal of Physics D: Applied Physics, 49 08LT01 (2016), doi: 10.1088/0022-3727/49/8/08LT01
  2. V. Caligiuri, R. Dhama, K. V. Sreekanth, G. Strangi and A. De Luca, Dielectric singularity in hyperbolic metamaterials: the inversion point of coexisting anisotropies, Scientific Reports, 6, 20002 (2016), doi: 10.1038/srep20002
  3. K. V. Sreekanth, A. De Luca and G. Strangi, Improved transmittance in metal-dielectric metamaterials using diffraction grating, Applied Physics Letters 104, 171904 (2014), doi:10.1063/1.4875555
  4. K. V. Sreekanth, K. H. Krishna, A. De Luca and G. Strangi, Large spontaneous emission rate enhancement in grating coupled hyperbolic metamaterials, Scientific Reports 4 , 6340 (2014), doi: 10.1038/srep06340
  5. K. V. Sreekanth, A. De Luca and G. Strangi, Excitation of volume plasmon polaritons in metal-dielectric metamaterials using 1D and 2D diffraction gratings, Journal of Optics 16, 105103 (2014), doi: 10.1088/2040-8978/16/10/105103
  6. M. Esposito, V. Tasco, F. Todisco, A. Benedetti, D. Sanvitto and A. Passaseo, Three dimensional chiral metamaterial nanospirals in the visible range by vertically compensated focused ion beam induced-deposition, Advanced Optical Materials 2, 154-161 (2014), doi: . 10.1002/adom.201300323
  7. M. Esposito, V. Tasco, M. Cuscunà, F. Todisco, A. Benedetti, I. Tarantini, M. De Giorgi, D. Sanvitto, A. Passaseo, Nanoscale 3D chiral plasmonic helices with circular dichroism at visible frequencies, ACS Photonics 2, 105–114(2015), doi: 10.1021/ph500318p.
  8. M. Esposito, V. Tasco, F. Todisco, M. Cuscunà, A. Benedetti, D. Sanvitto, A. Passaseo, Triple-helical nanowires by tomographic rotatory growth for chiral photonics, Nature Communications 6, 6484(2015), doi: 10.1038/ncomms7484
  9. M. Esposito, V. Tasco, F. Todisco, A. Benedetti, I. Tarantini, M. Cuscunà, L. Dominici, M. De Giorgi, A. Passaseo, Tailoring chiro-optical effects by helical nanowire arrangement, Nanoscale 7, 18081-18088 (2015), doi: 10.1039/C5NR04674B.
  10. M. Esposito, V. Tasco, F. Todisco, M. Cuscunà, A. Benedetti, M. Scuderi, G. Nicotra, and A. Passaseo, Programmable Extreme Chirality in the Visible by Helix-Shaped Metamaterial Platform, Nano Letters 16 (9), 5823-5828 (2016), DOI: 10.1021/acs.nanolett.6b02583
  11. De Luca, A. Iazzolino, J.-B. Salmon, J. Leng, S. Ravaine, A. N. Grigorenko and G. Strangi, Experimental evidence of exciton-plasmon coupling in densely packed dye doped core-shell nanoparticles obtained via microfluidic technique, J. of Appl. Phys. 116, 104303, (2014), DOI: 10.1063/1.4895061
  12. Infusino, A. De Luca, A. Veltri, C. Va?zquez-Va?zquez, M. A. Correa-Duarte, R. Dhama and G. Strangi, Loss-Mitigated Collective Resonances in Gain-Assisted Plasmonic Mesocapsules, ACS Photonics 1, 371-376 (2014), DOI: 10.1021/ph400174p
  13. K.V. Sreekanth, A. De Luca, and G. Strangi, Experimental demonstration of surface and bulk plasmon polaritons in hypergratings, Sci. Rep. Nature 3, 3291, (2013) – DOI:10.1038/srep03291
  14. K. V. Sreekanth, A. De Luca and G. Strangi, Negative refraction in graphene-based hyperbolic metamaterials, Appl. Phys. Lett., 103, 023107 (2013), DOI: 10.1063/1.4813477
  15. A. De Luca, N. Depalo, E. Fanizza, M. Striccoli, M. L. Curri, M. Infusino, A. R. Rashed, M. La Deda, G. Strangi, Plasmon Mediated super-absorber flexible nanocomposites for metamaterials, Nanoscale, 5, 6097-6105 (2013), DOI: 10.1039/C3NR00988B
  16. De Luca, A; Ravaine, S; La Deda, M; Scaramuzza, N; Bartolino, R; Strangi, G, Gain functionalized core-shell nanoparticles: The way to selectively compensate absorptive losses, J. Mater. Chem., 2012,22, 8846, DOI: 10.1039/C2JM30341H
  17. L Ricciardi, M Martini, O Tillement, L Sancey, P Perriat, M Ghedini, E I Szerb, Y J Yadav, M La Deda, Multifunctional material based on ionic transition metal complexes and gold-silica nanoparticles: Synthesis and photophysical characterization for application in imaging and therapy, J. Photochem. Photobiol. B: Biol., 140, 396. (2014), DOI: 10.1016/j.jphotobiol.2014.09.005
  18. Ritacco, T.; Ricciardi, L.; La Deda, M.; et al., Controlling the optical creation of gold nanoparticles in a PVA matrix by direct laser writing, Journal of the European Optical Society-Rapid Publications 11, Article Number: 16008 (2016), DOI: 10.2971/jeos.2016.16008

Projects

Gain-Plasmon Coupling in Metal-Dielectric Nanostructures: Loss Compensation towards Laser Action, PRIN 2012

Beyond ‘Nano: Materials and processes BEYOND the NANO ‘scale (2012-2015)

Latest News

Loretta del Mercato, si aggiudica l'ERC STARTING GRANT 2017

Loretta del Mercato, si aggiudica  l'ERC STARTING GRANT 2017

uno dei bandi più competitivi a livello europeo.

Lecce, 6 settembre 2017 

Lo European Research Council, che promuove la ricerca di eccellenza in Europa, nei giorni scorsi ha reso noti i nomi dei 406 vincitori della selezione ERC STARTING GRANT 2017, il bando tra i più competitivi a livello internazionale.

Su 3085 progetti presentati, 406 i progetti selezionati a cui sono stati destinati i 605 i milioni di euro di investimento. 48 le nazioni di provenienza dei ricercatori, soltanto 17 gli Italiani che condurranno le loro ricerche nel nostro paese, tra cui Loretta del Mercato, ricercatrice dell'Istituto di Nanotecnologia del Consiglio Nazionale delle Ricerche di Lecce.

Un importante riconoscimento alla ricerca nel settore della medicina di precisione condotta presso il CNR NANOTEC, un indiscusso premio al talento della giovane ricercatrice che, a 38 anni e un contratto a tempo determinato, sarà a capo del progetto "Sensing cell-cell interaction heterogeneity in 3D tumor models: towards precision medicine – INTERCELLMED".

Il progetto, il cui obiettivo è affrontare uno dei problemi più spinosi della ricerca sul cancro, ovvero la difficoltà nel trasformare i risultati delle ricerche scientifiche in applicazioni cliniche per i pazienti e che vedrà coinvolto l'Istituto tumori "Giovanni Paolo II" di Bari, si propone di sviluppare nuovi modelli in vitro 3D di tumore del pancreas, alternativi ai modelli animali, ingegnerizzati con un set di sensori nanotecnologici che consentiranno di monitorare le interazioni delle cellule tumorali con il loro micorambiente, verificare l'appropriatezza delle terapie prima della somministrazione ai pazienti oncologici e quindi prevedere la risposta dei singoli pazienti ad una o più terapie antitumorali.

La realizzazione di queste piattaforme 3D multifunzionali consentirà di superare le evidenti differenze intercorrenti tra "modelli animali" ed esseri umani fornendo dati attendibili ed in tempi più rapidi rispetto ai dati ottenuti tramite lunghi e costosi procedimenti di sperimentazione sugli animali. Le tecnologie e i modelli sviluppati saranno estesi anche ad altre forme di tumori solidi nonché impiegati per studi nell'ambito della ingegneria tissutale e della medicina rigenerativa.

Rassegna stampa e Video

Zeiss Microscopy Technology and Complete Correlative Workflow

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Zeiss Microscopy Technology and Complete Correlative Workflow

Lecce, Italy, 2017 Wednesday July 19th 

CNR NANOTEC @ Lecce, Aula Seminari – pal. G, Piano Terra

Program - PDF

Zeiss, as microscopy technology leader, provides the unique complete imaging solution ranging from light, confocal, electron, ion and Xray modalities with a complete and straightforward correlative workflow. An overview of different technologies will be presented with a special focus on X-Rray microscopy.

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MCS 2017

International Workshop on Micropropulsion and CubeSats

Bari, Italy, 26 - 27 June 2017

Program - MSC2017

This narrow-field, invited-only meeting is the first attempt to bring together the Materials and Micropropulsion communities with a view to contribute to the development of the Global Materials and Micropropulsion Roadmap, and set such meetings to a regular basis.