Les ondes térahertz au secours de l’Internet sans fil

Despite the expansion of the 4G network, wireless Internet still needs a great deal of innovation if it is to achieve the same speeds as fibre optics. An international team, based at the Institute of Electronics, Microelectronics and Nanotechnology, has shown that waves in the terahertz frequency range could take over from wired networks. This work is published in Nature Photonics.

IEMN (A. Duchêne) - Visual illustration of the main component, i.e. the component that makes it possible to "switch" from the world of optical fibres (bottom left) to the world of terahertz (the spiral) for telecoms (small shapes top right).

In 2018, the Internet will account for more than 130 billion billion bytes of data exchanged per month. Since most of this growth is expected on wireless channels, ultra high-speed transport infrastructures will have to evolve considerably. This requires faster components, because the increase in throughput will only be absorbed if the frequency of the waves rises towards the beginning of the THz band (between 220 and 350 GHz). Researchers at the Institute of Electronics, Microelectronics and Nanotechnology (IEMNCNRS/Université Lille-1/ISEN Lille/Université de Valenciennes et du Hainaut-Cambrésis/École Centrale de Lille) were able to set up an initial demonstrator, based on optoelectronic devices that transform optical fibre signals into radio signals.

These demonstrations use optoelectronic components that perform 'photomixing'. In this process, two lasers are sent to the same photodiode, which transforms them into a signal corresponding to the difference in their wavelengths. This converts optical signals of the order of a hundred THz, typical of optical fibres, into a radio signal of around 300 GHz. At the IEMN, a wireless data rate of 32 Gbit/s was transmitted over several tens of metres using a frequency of around 400 GHz. These frequencies offer a very good compromise between the capacity of the components and the attenuation of the waves in the air, which will eventually make it possible to achieve the range required for urban use. This step will enable us to move towards the next challenges: transfer speeds in excess of 100 Gbit/s and transmissions over more than a kilometre.

The technology associated with this work has been developed thanks to the network of major technology centres. RENATECH network.with the help of laboratories PhLAM and IRCICA and support from the ANR COM'TONIQ programme, the Equipex FLUX, Excelsior and the CPER Photonics for society.

References :

Advances in terahertz communications accelerated by photonics,
T. Nagatsuma, G. Ducournau and C.C. Renaud
Nature Photonics - 10, 371-379 (2016)
DOI: 10.1038/NPHOTON.2016.65

Contacts chercheurs :
Guillaume Ducournau – IEMN
Contact communication INSIS :
insis.communication@cnrs.fr

Productions, activités et usages des « Nanos » : Les conditions de la confiance

Friday 10 March, the Lilliad Learning Center Innovation de Villeneuve d'Ascq (located on the Cité Scientifique campus in Villeneuve-d'Ascq within the European Metropolis of Lille) will host the NanoLille day.

This discussion day is aimed at all those involved in nanotechnologies or interested in their development and their social and economic implications. Its aim is to provide a particularly well-informed overview of the knowledge available and the gaps in each of the fields concerned by the development of nanomaterials and nanotechnologies, and to promote a collective debate on the prerequisites for the sustainable and responsible development of these new technologies.

Programme, prices and registration : http://www.nanoresp.fr/evenements/nano-lille/

Contact: forum@nanoresp.fr

The organisers

The NanoRESP Forum (www.nanoresp.fr) is a multi-stakeholder dialogue (industry, academia, associations, public authorities) on nanotechnologies initiated in 2013. Supported by a public-private alliance, it aims to develop cooperative vigilance in relation to controversies and to identify responsible practices in a climate of uncertainty.

The Nanoscoope project (http://nanoscoope.iemn.univ-lille1.fr/) is a researcher-citizen project funded by the Hauts-de-France Region. Since 2013, it has been organising multi-stakeholder, cross-disciplinary consultation workshops on the various issues surrounding the development of nanotechnologies. Nanoscoope has joined forces with other partners to organise this event on 10 March, which marks the end of the project in this form.

The National metrology and testing laboratory (LNE, http://www.lne.fr/), a public industrial and commercial establishment (EPIC), is the national reference laboratory for industry in the field of measurement (metrology). It is attached to the Ministry of Industry.

The Directorate-General for Enterprise (DGE) of the French Ministry for the Economy, Industry and the Digital Economy (http://www.entreprises.gouv.fr/)'s mission is to develop the competitiveness and growth of companies in industry and services, in particular by supporting and disseminating innovation with a view to sustainable growth and employment.

Séminaire : Nanostructuration at two scales in III V semiconductors to control both electronic states and photonic states: photonic crystal quantum cascade laser

04 april At 11h00 – Amphiteather IEMN-LCI Villeneuve d’Ascq
Dr. Romain Peretti, IEMN

On one hand, periodically repeated change of refractive index at the wavelength scale known as photonic crystal (PhC) affects the motion of photons in much the same way that ionic lattices affect electrons in solids. This means photons now can be depicted by Bloch modes and the well know band diagram to describe their motion in the material. Such PhC when unidimensional can be used for instance as antireflective coating when the 2 dimensional counterpart is used in solar cells or micro laser.

 

On the other hand, periodically repeated stack of semiconductor multiple quantum well heterostructures allows achieving intersuband transition in III-V semiconductors. This idea was first proposed in R.F. Kazarinov and R.A. Suris in 1971 with in mind the idea of creating a new kind of laser. Such quantum cascade laser (QCL) where then demonstrated by Faist et al. in 1994. QCLs are unipolar and laser emission coming from this intersuband transition. Since then, QCL’s made huge progresses and are now reaching more than one watt of power in the mid infrared range of the spectrum (3- 12µm), at room temperature. Still these high power lasers are multimode and all the designs aiming at single mode operation suffer from additional modes apparition when scaling up the device to reach high power. However, several applications such as military countermeasure, or laser surgeries needs high power single mode operation. Pulled by this demand, we combined QCL and PhC adopting an innovative regrowth approach to enhance even more the thermal dissipation needed by the device.

Séminaire : Nanostructured GaN devices for power applications and beyond – Pr. Elison Matioli

Dans le cadre du thème GaN, l’IEMN accueille :

Lundi 27 Mars 2017 – IEMN LCI Villeneuve d’Ascq, Salle du conseil – 10:30
Nanostructured GaN devices for power applications and beyond
Elison Matioli, Ecole Polytechnique Fédérale de Lausanne (EPFL)

In this talk, I will present some of the nanowire-based technologies developed in our group to significantly enhance the performance of high-voltage GaN power devices, such as Schottky barrier diodes (SBDs) and high electron mobility transistors (HEMTs). This presentation will cover high-performance AlGaN/GaN HEMTs on silicon substrate based on nanowire tri-gate architectures. The optimized tri-gate geometry led to reduced off-state leakage current (Ioff) and sub-threshold slope (SS), increased on/off ratio, and improved breakdown voltage (Vbr) of the device. With a gate-to-drain separation (LGD) of 15 μm, hard Vbr up to 1755 V at Ioff of 45 μA/mm with high soft Vbr of 1370 V at Ioff = 1 μA/mm were achieved, rendering an excellent high-power figure of merit (FOM) up to 1.25 GW/cm2.

These nanowire-based technologies were also applied for AlGaN/GaN SBDs on silicon substrates. An optimized hybrid of tri-anode and tri-gate architectures led to SBDs exhibiting high Vbr, low reverse leakage current (IR), and small turn-on voltage (VON) of 0.76 ± 0.05 V since the tri-anode architecture formed a direct Schottky contact to the 2D electron gas (2DEG). The reverse characteristics were controlled electrostatically by an embedded tri-gate transistor, instead of relying only on the Schottky barrier, which resulted in low IR below 10 nA/mm at large reverse biases up to 500 V. In addition, these devices exhibited record Vbr up to 1325 V at IR of 1 μA/mm, rendering an excellent high-power FOM of 939 MW/cm2. These results unveil the significant potential of nanostructured GaN transistors for future power applications.

Finally, I will discuss the application of these nanostructures to better understand the electron transport in GaN-based heterostructures, which was exploited to demonstrate new ballistic devices operating at room temperature. The fast transport of ballistic electrons could offer a pathway for future room-temperature high-frequency ballistic devices.

Biography: Elison Matioli is an assistant professor in the institute of electrical engineering at Ecole Polytechnique Fédérale de Lausanne (EPFL). He received a B.Sc. degree in applied physics and applied mathematics from Ecole Polytechnique (Palaiseau, France) in 2006 and a Ph.D. degree from the Materials Department at the University of California, Santa Barbara (UCSB) in 2010. He was a post-doctoral fellow in the Department of Electrical Engineering and Computer Science at the Massachusetts Institute of Technology (MIT) until 2014. His expertise is in semiconductor and nanostructure growth by metal-organic chemical vapor deposition (MOCVD), device fabrication and development of advanced numerical models to simulate device properties. He has received the Outstanding Graduate Student – Scientific Achievement Award for his Ph.D. thesis, the IEEE Electron Devices Society George Smith Award for his demonstration of high-efficiency nanostructured power electronic devices and the ERC Starting Grant in 2015.

 

The 2017 thesis topic offers are online ...

The doctorate: a passport to the future

  • The doctorate provides an opportunity to deepen the research methods acquired during the first cycles of higher education, but also to take a different look at these methods and possibly to cooperate in improving them.
  • A doctorate is a diploma required for entry to almost all national and international research bodies.
  • In France, a doctorate is required to enter the competitive examination for Maître de Conférences and then Professeur des Universités.
  • The doctorate is also the gateway to the most senior positions in most national/international research establishments, whether public or private.

View the 2017 subjects (PDF)

 

Séminaire : ‘Optical Frequency Combs for Ultra-Low Phase-Noise Microwave Signal Generation and Laser Activities at LP2N ‘

Speaker : Giorgio Santarelli (LP2N-Bordeaux)
Date : 31 January at 11h00
Location :  Amphiteather IEMN-LCI

Low-phase-noise and frequency stable microwave signals are crucial for a wide variety of scientific and technological applications including atomic frequency standards, phased-array radars, arbitrary waveform generation, photonic processing and very long baseline interferometry. One challenging aim for researchers has been the development of a single device that exhibits the ultimate performance in multiple aspects of signal purity for instance to have low phase fluctuations across the spectrum from low Fourier frequencies (1Hz) out to the highest (1MHz) frequencies of interest. One promising route is the low-noise optical frequency division of a laser that has been stabilized to a mode of a vibration-insensitive reference cavity. In these circumstances the divided signal carries the frequency stability of the original signal while delivering an improved signal-to-noise ratio by the division of the phase fluctuations. The photonic shot noise in optical to electrical pulse conversion in a photodiode which was believed to impair the ultra-low phase noise generation has been greatly improved by combining pulse interleavers for increased effective repetition rates and apparent sub-shot-noise photodetection ([1]). With this last technique, it was shown that the shot-noise limit is greatly improved over that of cw lasers in the short (<1ps) optical pulses limit. There have been several developments in the field of photonic microwave synthesis showing very low absolute or residual phase noise using femtosecond frequency combs based on either modelocked Ti:Sapphire and Erbium fiber lasers [2,3]. Fibre systems are morecompact, robust and power efficient than Ti:Sapphire, very recently we have demonstrated the lowest phase noise by of -106(<-173) dBc/Hz@1Hz(10kHz) offset carrier. I will present a review the recent advances in this domain and the latest results [4]. In addition, I will shortly present laser developments at LP2N [5].

[1]F. Quinlan et al. “Exploiting shot noise correlations in the photodetection of ultrashort optical pulse trains”, Nature Photonics, 7, p. 290 (2013). [2]T. M. Fortier, F. Quinlan, A. Hati, C. Nelson, J. A. Taylor, Y. Fu, J. Campbell, and S. A. Diddams, « Photonic microwave generation with high-power photodiodes, » Opt. Lett. 38, 1712-1714 (2013) [3]F. Quinlan, F. N. Baynes, T. M. Fortier, Q. Zhou, A. Cross, J. C. Campbell, and S. A. Diddams, « Optical amplification and pulse interleaving for low-noise photonic microwave generation, » Opt. Lett. 39, 1581-1584 (2014). [4]X.Xieet al., G. Santarelli, and Y. Le Coq, « ) Photonic microwave signals with zeptosecond-level absolute timing noise » Nat. Phot.(2016). [5]G. Guiraud, N. Traynor, G. Santarelli, « High-power and low-intensity noise laser at 1064nm, » Opt. Lett. 41, 4040-4043

Séminaire : Artificial Neuron performance: is it possible to outperform biology?

Speaker: Alain Cappy (IEMN)
Date : 17 January at 11h00
Location :  Amphiteather IEMN-LCI

Abstract: 

Traditional computing technology based on the Von Neumann architecture is facing fundamental limits in the context of the end of Moore's law. Among them is a poor energy efficiency. This situation motivates the use of different processing information paradigms, such as the use of spiking neural networks (SNNs), which also introduce cognitive characteristics. In this context, this talk presents the design of an original artificial neuron (AN) in standard 65nm CMOS technology, optimized for energy efficiency. The main features of the fabricated ANs are: (i) an energy efficiency of few fJ/spike, that is, between 2 to 3 orders of magnitude lower than the current state-of-the-art, (ii) a standby power, obtained when the neuron remains at rest, not exceeding 10s of pW (iii) a silicon consumption area between 35 and 200 µm2(iv) a spiking frequency able to reach 10s of kHz, a useful feature within a biocomputing context. The performance level, achieved in standard 65 nm CMOS technology, can address various contexts such as highly integrated neuro-processors for robotics, neuroscience or medical applications.

Batteries miniatures nomades : nouveau design 3D

DES SCIENTIFIQUES FRANÇAIS PROPOSENT UN NOUVEAU DESIGN DE MICRO-BATTERIES POUR OBJETS CONNECTÉS

Le développement des objets intelligents et connectés requiert des sources d’énergies autonomes, décentralisées et souvent miniatures, par exemple pour alimenter des micro-capteurs. La question de leur design est cruciale : chaque µm² gagné permettant d’augmenter la densité d’énergie de la batterie.

Des chercheurs français des laboratoires IMN, IEMN, UCCS et du LRCS, en partenariat avec un laboratoire américain (Argonne National Lab, ligne synchrotron APS), essaient de développer des micro-batteries lithium-ion « tout solide » capables d’alimenter ces objets afin de les rendre autonomes. Rassemblés autour d’un chercheur de l’IEMN, ils proposent une architecture performante permettant de répondre à de nombreux problèmes souvent rencontrés dans la création de batteries miniatures.

Cette architecture est construite à partir de wafer de silicium, matériau de choix dans l’industrie de la microélectronique. Le wafer est ensuite usiné pour fabriquer une structure 3D originale et robuste à base de micro-tubes simple ou double qui servira d’encrage à la micro-batterie. Cette gravure permet d’atteindre un gain de surface proche de 50 sans dénaturer son empreinte surfacique : une micro-batterie présentant une empreinte surfacique de 1 mm2 développe donc une surface spécifique de 50 mm2. Cette structuration 3D à base de micro-tubes est protégée par un brevet.

Cette architecture 3D a pour originalité d’être à une échelle micrométrique et non nanométrique. Les chercheurs ont fait ce choix car les approches nanométriques (avec des nanotubes de carbone ou des nanofils de silicium) ont le défaut d’être plus fragiles et flexibles. Par ailleurs, la faible distance entre 2 nanostructures limite drastiquement l’épaisseur de matériaux actifs déposables et donc les performances en densité d’énergie.

L’avantage de ce travail réalisé par deux doctorants (Manon Létiche – thèse IEMN/UCCS et Jeremy Freixas  – thèse IEMN/IMN) à l’échelle du micromètre est donc double. D’abord, il confère au substrat micro-structuré une robustesse permettant le dépôt de toutes les couches nécessaires (et d’épaisseur suffisante) pour produire des micro-batteries 3D de haute performance. Cette robustesse permet en outre de pouvoir manipuler les wafers de silicium sans craindre de briser les structures 3D qui résisteront ainsi à l’enduction centrifuge de résine photosensible visqueuse classiquement utilisée en microélectronique… Le tout présentant des gains de surface finalement comparables, voire meilleurs, que celui des nanostructures 3D.

Une fois ce substrat 3D de qualité créé, les chercheurs ont dû déposer dessus les matériaux nécessaires pour donne vie à la micro-batterie Li-ion. Leur travail étant une première preuve de concept et ayant pour but la finalisation d’un prototype, ils ont développé 4 des 6 couches de matériaux nécessaires à l’obtention d’une batterie complète.

La technique utilisée pour le dépôt de ces 4 premières couches et celle du dépôt par couche atomique (ALD), technique déjà utilisée à l’échelle industrielle, par exemple dans le cas du photovoltaïque, de la fabrication de transistor ou de mémoire vive dynamique (DRAM). Elle leur a permis de créer une couche isolante (Al2O3), un collecteur de courant (Pt), une électrode négative (TiO2) et un électrolyte  (Li3PO4)

microtubes_s

Contrairement à beaucoup de confrères et à ce qui se fait classiquement dans la fabrication de batterie, l’électrolyte est sous forme solide et non liquide. Ainsi, ces micro-batteries ne souffrent pas des limites des électrolytes liquides : inflammabilité, évaporation des solvants, fuite potentielle. Les dépôts de ces 4 couches épousent parfaitement les formes complexes des microstructures 3D (on parle de conformité) et l’électrolyte solide Li3PO4 fabriqué par ALD combine une fenêtre de stabilité électrochimique élevée (4.2 V), une haute conductivité ionique et une faible épaisseur (10 à 50 nm) générant une faible résistance surfacique.

L’ALD permet, en plus, une très bonne qualité des dépôts comme ont pu le vérifier les chercheurs par plusieurs techniques de caractérisations avancées (FIB TEM, EDX STEM, tomographie TXM synchrotron) : conformité proche de 100 %, pas d’inter-diffusion entre les couches ALD et absence de trous/fissures/craquelures.

Au final, l’équipe a montré un design attractif en regard du cahier des charges des objets connectés/miniaturisés (Internet of Things). Ces résultats découlent du travail collaboratif entre 5 laboratoires aux compétences complémentaires. A court terme, l’équipe de chercheurs va travailler sur la mise au point de films minces de matériaux d’électrode positive par ALD afin de pouvoir créer des prototypes de micro-batteries 3D fonctionnels dont les performances en densité d’énergie dépasse celles des micro-batteries planaires.

wileyAtomic layer deposition of functional layers for on Chip 3D Li-ion all solid state microbattery.
M. Létiche, E. Eustache, J. Freixas, A. Demortière, V. De Andrade, L. Morgenroth, P. Tilmant, F. Vaurette, D. Troadec, P. Roussel, T. Brousse, C. Lethien. Advanced Energy Materials, le 11 octobre 2016.
> Consulter le site web

  • IEMN CNRS UMR 8520 – Université de Lille Sciences et Technologies
  • UCCS CNRS UMR 8181 – Université Lille 1 Sciences et Technologies
  • IMN CNRS UMR 6502 – Université de Nantes
  • LRCS CNRS UMR 7314 – Université de Picardie Jules Verne

Contact chercheur : christophe.lethien@iemn.univ-lille1.fr

Télécharger le communiqué de Presse

La photonique et les communications sans fil térahertz

« Les communications sans fil térahertz: état de l’art des performances et intérêt des dispositifs issus de la photonique pour le développement des démonstrateurs amont: cet article présente le rôle clé qu’a joué et que joue encore la photonique pour l’avancée dans ce domaine de recherche. Quelques développements récents effectués à l’IEMN y sont présentés »

nature_photonicsAdvances in terahertz communications accelerated by photonics

Tadao Nagatsuma, Guillaume Ducournau & Cyril C. Renaud

Nature Photonics 10, 371–379 (2016) │ Published online 31 May 2016

Abstract:

Almost 15 years have passed since the initial demonstrations of terahertz (THz) wireless communications were made using both pulsed and continuous waves. THz technologies are attracting great interest and are expected to meet the ever-increasing demand for high-capacity wireless communications. Here, we review the latest trends in THz communications research, focusing on how photonics technologies have played a key role in the development of first-age THz communication systems. We also provide a comparison with other competitive technologies, such as THz transceivers enabled by electronic devices as well as free-space lightwave communications.

Examples of THz links using photonics-based transmitters.

IEMN

Enabling technologies based on photonics and new materials for future THz communications.
 IEMN

 

 

> Consulter l’article dans son intégralité

Nanoécole Lille, on en parle …

Passionnée, Patricia Lefebvre a expliqué son métier par le concret

Passionnée, Patricia Lefebvre a expliqué son métier par le concret

 

 

Auchel : une ingénieure du CNRS compte sur la relève des élèves de Lavoisier

Susciter des vocations, des projets de carrière scientifique, parmi les élèves de terminale, première et seconde, c’était bien là l’objectif d’Alberto Da Silva, professeur de physique à Lavoisier lorsqu’il a organisé la venue de Patricia Lefebvre, ingénieure au CNRS (Centre National de la Recherche Scientifique) de l’IEMN (Institut d’Electronique, de Microélectronique et de Nanotechnologie) à l’Université de Lille 1.

 

 

Vendredi, plus de deux cents élèves ont profité de la rencontre, avec des interventions adaptées au programme de chaque niveau. Les nanotechnologies et le nanomonde, illustré par quelques petites expériences. Patricia a aussi parlé de son laboratoire, où travaillent cinq cents personnes, et de tous les métiers nécessaires à son bon fonctionnement : techniciens, opérateurs, chercheurs, ingénieurs…

" Nous avons besoin de plus en plus de compétences différentes. Plus tard, dans votre métier, on vous demandera d’être compétent là où vous êtes. On espère que vous, lycéens, prendrez la relève », souffle-t-elle.

Pour le professeur de physique, cet échange est à reconduire.

" Même si cela ne crée que quatre vocations, eh bien ce sera déjà cela. Le message que nous, professeurs, véhiculons au quotidien est très important mais qui mieux qu’une ingénieure pour parler de son métier. Il est important de multiplier les discours. D’autant plus qu’il s’agit ici d’une femme et qu’elles ne sont pas assez dans le domaine scientifique alors qu’il y a plus de filles que de garçons qui obtiennent un bac S. "

 

Publiée le 23/05/2016, La Voix du Nord

Voix du Nord