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  • ['Photonique']

    (in french) Cristaux photoniques à gradient et dispositifs


      Eric Akmansoy.

    (in french)

    Cadre général

    D’une part, les cristaux photoniques à gradient permettent un réel contrôle de la propagation de la lumière par le profil de leur bandes photoniques[1]. De l’autre, l’optique à gradient d’indice (GRIN Optics) connaît un renouveau parce qu’elle offre de nouveaux degrés de liberté pour le « design» de dispositifs optiques [2]. Cependant, la fabrication du profil d’indice à gradient est difficile. Les nanotechnologies permettent de fabriquer facilement des cristaux photoniques, ce que nous considérerons en concevant des cristaux photoniques à gradient pour réaliser des dispositifs optiques à gradient d’indice. 

    Pour démontrer que les cristaux photoniques à gradient permettent de contrôler la propagation du champ électromagnétique, nous avons mis en en évidence expérimentalement un « mirage photonique» (cf. fig. 2)[1]. Nous concevons, simulons numériquement et caractérisons des cristaux photoniques à gradient pour des dispositifs à gradient d’indice (cf. fig. 1)[3, 4]). Par ex., nous avons conçu une lentille plate que nous avons caractérisée dans le domaine des micro-ondes [5]. Récemment, nous avons conçu et simulé une lentille de Luneburg [6] (cf. fig. 1). Pour concevoir ces dispositifs optiques, nous mettons en oeuvre une ingénierie des courbes iso-fréquences qui traduisent la relation de dispersion des cristaux photoniques. Notre but est de monter en fréquences vers le domaine optique. La démonstration expérimentale de tels composants est une fin en soi, car il y a un défi technologique à les fabriquer. Nous envisageons un grand nombre d’applications à ces cristaux photoniques à gradient pour la photonique intégrée, le laboratoire sur puce, la biophotonique, le pompage optique de matériaux organiques, etc. 

    Plan du stage

    Durant ce stage, des dispositifs à cristaux photoniques seront conçus et simulés numériquement. Ils fonctionneront dans différentes gammes de fréquences, de l’optique aux micro-ondes. Le but est de pouvoir les fabriquer et les caractériser par la suite. Ce stage pourra se poursuivre par une thèse.

    Bibliographie

    [1]    Éric Akmansoy, Emmanuel Centeno, Kevin Vynck, David Cassagne, and Jean-Michel Lourtioz, Graded photonic crystals curve the flow of light : An experimental demonstration by the mirage effect, Appl. Phys. Lett. 92, 133501 (2008) 

    [2]    Predrag Milojkovic, Stefanie Tompkins, Ravindra Athale, Gradient Index Optics, Optical Engineering, November 2013/Vol. 52(11), p. 112101-1 

    [3]    F. Gaufillet, É. Akmansoy, Graded photonic crystals for graded index lens, Optics Communications, Volume 285, 2638 (2012). 

    [4]    F. Gaufillet, É. Akmansoy, Design of flat graded index lenses using dielectric Graded Photonic Crystals, Optical Materials, Vol. 47, 555-560 (2015) 

    [5]    F. Gaufillet and E. Akmansoy. Design and experimental evidence of a flat graded-index photonic crystal lens. Journal of Applied Physics, 114(8) :083105, 2013. 

    [6]    F. Gaufillet and E. Akmansoy. Graded photonic crystals for Luneburg lens, IEEE Photonics Journal, vol. 8, 11 (2016) 

    [7]    CVI Melles Griot. Gradient-Index Lenses – http://pdf.directindustry.com/pdf/cvi-melles-griot/gradient-index-lenses/12567-66963.html. 

    [8]    Z. Han, X. Checoury, D. Néel, S. David, M. El Kurdi, P. Boucaud, Optimized design for ultra-high Q silicon photonic crystal cavities, Optics Communications 283 (21) (2010) 4387 – 4391.

    Bibliographie

    [1]    Éric Akmansoy, Emmanuel Centeno, Kevin Vynck, David Cassagne, and Jean-Michel Lourtioz, Graded photonic crystals curve the flow of light : An experimental demonstration by the mirage effect, Appl. Phys. Lett. 92, 133501 (2008) 

    [2]    Predrag Milojkovic, Stefanie Tompkins, Ravindra Athale, Gradient Index Optics, Optical Engineering, November 2013/Vol. 52(11), p. 112101-1 

    [3]    F. Gaufillet, É. Akmansoy, Graded photonic crystals for graded index lens, Optics Communications, Volume 285, 2638 (2012). 

    [4]    F. Gaufillet, É. Akmansoy, Design of flat graded index lenses using dielectric Graded Photonic Crystals, Optical Materials, Vol. 47, 555-560 (2015) 

    [5]    F. Gaufillet and E. Akmansoy. Design and experimental evidence of a flat graded-index photonic crystal lens. Journal of Applied Physics, 114(8) :083105, 2013. 

    [6]    F. Gaufillet and E. Akmansoy. Graded photonic crystals for Luneburg lens, IEEE Photonics Journal, vol. 8, 11 (2016) 

    [7]    CVI Melles Griot. Gradient-Index Lenses – http://pdf.directindustry.com/pdf/cvi-melles-griot/gradient-index-lenses/12567-66963.html. 

    [8]    Z. Han, X. Checoury, D. Néel, S. David, M. El Kurdi, P. Boucaud, Optimized design for ultra-high Q silicon photonic crystal cavities, Optics Communications 283 (21) (2010) 4387 – 4391.

    followed PhD

    fichier joint

    eric.akmansoy@u-psud.fr - 01 69 15 41 43

  • ['Photonique']

    (in french) Métamatériaux « tout diélectrique» : indice nul et indice négatif


      Eric Akmansoy.

    (in french)

     

    Proposition de stage de master 2

    Métamatériaux « tout diélectrique» : 

     

    indice nul et indice négatif 

     Éric Akmansoy 

    Département Photonique

    Les métamatériaux ont ouvert un nouveau champ en physique et en ingénierie. En effet, ces matériaux artificiels structurés possèdent des propriétés électromagnétiques surprenantes, telles que l’indice de réfraction négatif ou nul. L’indice de réfraction négatif permet la la focalisation sub-longueur d’onde par la lentille parfaite, c-à-d, une lentille plate s’affranchissant du critère de Rayleigh. Un autre phénomène que permettent les métamatériaux est la cape d’invisiblité. Les métamatériaux se développent maintenant vers la mise en oeuvre de composants [1]. Les métamatériaux « tout diélectrique» sont prometteurs car ils subissent de faibles pertes et leur géométrie est simple [2]. 

    Nous concevons, fabriquons et caractérisons des métamatériaux « tout diélectrique» opérant des micro-ondes au térahertz. Ils fonctionnent à partir des résonances de Mie de résonateurs diélectriques à grande permittivité. Nous avons mis en évidence un indice de réfraction négatif à 10 GHz [3, 4]. Récemment, nous avons aussi conçu une « métalentille» i.e., une lentille plate à gradient d’indice fonctionnant au térahertz [5]. 

    Durant ce stage, le couplage entre les modes de résonance sera étudié de façon à mettre en évidence un indice de réfraction négatif et un indice de réfraction quasi-nul. Les métamatériaux « tout diélectrique» seront simulés numériquement au moyen d’un logiciel afin d’extraire les paramètres électromagnétiques et l’indice de réfraction (cf. figure 1). Ce travail pourra être poursuivi par une thèse. 

     

    Fig. 1: Couplage entre les deux modes de résonance d’un métamatériau « tout diélectrique»le domaine téraHertz. Les trois zones du couplage sont mises en évidence  ; la courbe a la forme d’un diapason  : couplage faible  : pas d’indice négatif  ; couplage optimal (zone en grisé)  : l’indice est négatif  ; couplage fort  : l’indice n’est plus défini et les modes sont dégénérés. 

     

    Références

    [1]    N. I. Zheludev and Y. S. Kivshar, “From metamaterials to metadevices,”  Nat Mater, vol. 11, pp. 917–924, 11 2012.

    [2]    S. Jahani and Z. Jacob, “All-dielectric metamaterials,” Nat Nano, vol. 11, pp. 23–36, 01 2016.

    [3]    T. Lepetit, E. Akmansoy, and J.-P. Ganne, “Experimental evidence of resonant effective permittivity in a dielectric metamaterial,” Journal of Applied Physics, vol. 109, no. 2, p. 023115, 2011.

    [4]    T. Lepetit, É. Akmansoy, and J.-P. Ganne, “Experimental measurement of negative index in an all-dielectric metamaterial,” Applied Physics Letters, vol. 95, no. 12, p. 121101, 2009.

    [5]    F. Gaufillet, S. Marcellin, and E. Akmansoy, “Dielectric metamaterial-based gradient index lens in the terahertz frequency range,” IEEE J Sel Top Quant, vol. 10. 1109/JSTQE. 2016. 2633825, 2017.

     

    followed PhD

    fichier joint

    eric.akmansoy@u-psud.fr - 01 69 15 41 43

  • ['Photonique']

    (in french) Photodiodes à avalanche dans la filière germanium pour le développement d’une nouvelle génération de récepteurs intégrés.


      Laurent Vivien.

    (in french)

    Afin d’adresser la problématique liée aux limitations des interconnections métalliques en termes de débits notamment,
    la photonique sur Silicium s’est imposée comme une technologie de choix. Bien que déjà disponible
    commercialement, des développements sont encore nécessaire pour adresser la demande croissante en débit des
    communications et ce pour chaque composant de base. D’un point de vue du récepteur, cela se traduit par des
    photodétecteurs toujours plus sensibles et rapides, tout en maintenant une faible consommation électrique. Le
    Germanium est un matériau de choix pour la photodétection en photonique sur Silicium puisqu’il est possible de
    l’épitaxier directement sur Silicium et qu’il offre une forte absorption aux longueurs d’onde utilisées pour les
    communications optiques (typ. 1300-1600nm). Des résultats préliminaires très prometteurs ont été obtenus sur des
    détecteurs à avalanche en germanium ouvrant les études vers de nouvelles configurations de récepteurs intégrés.
    Le sujet de stage propose d’étudier différentes configurations de détecteurs à avalanche germanium en étroite
    collaboration avec le CEA/Leti à Grenoble et le C2N à Orsay. Une première tâche consistera à étudier
    expérimentalement une nouvelle architecture basée sur une double hétéro-jonction Si/Ge/Si en mode photodiode et en
    mode avalanche pour l’évaluation de leurs caractéristiques. Des mesures DC et en rapidité seront effectuées.
    D’autres types de configurations de diodes seront également envisagés dans le cadre du stage, basés dans un premier
    temps sur la structure SACM (Separate Absorption Charge Multiplication).
    De plus, le candidat sera amené à étudier les propriétés physiques du GeSn pour la detection de la lumière dans le
    proche-IR et le moyen-IR. En effet, l’incorporation d’atome d’étain dans le germanium amène à considérablement
    changer la structure de bande pour aller vers un matériau à gap direct et étendre le spectre d’absorption vers le moyen
    IR.

     

    followed PhD

    fichier joint

    laurent.vivien@c2n.upsaclay.fr - 0169154070

  • ['Photonique']

    Graded Photonic Crystals Devices for Graded Index Optics


      Eric Akmansoy.

      

    Centre de Nanosciences et nanotechnologies

    UMR 9001 du CNRS,

    université Paris-Sud, université Paris-Saclay

    91 405 Orsay – France

      

    PhD research proposal

    Graded Photonic Crystals Devices for Graded Index Optics

     Éric Akmansoy 

    Département Photonique

    __________________ 

     

    General framework

    On the one hand, Graded Photonic Crystals (GPC) allow to efficiently control the flow of light thanks to the shape of their photonic bands, which we verified by demonstrating a “photonic mirage” at wavelength scale[1]. In the other hand, GRaded INdex (GRIN) optics is undergoing a renewal because it allows to downsize optical systems, opening a new way to optical design[2]. But GRIN optics was limited by a lack of easy to implement fabrication techniques. Nanotechnology enables to efficiently fabricate photonic crystals, which we will implement to fabricate GPC for GRIN optics. 

    We are designing, numerically simulating and characterising GPC devices (see fig.1)[3, 4]. More specifically, we have conceived a GRIN flat lens which we have characterised in the microwave[5]. Recently, we have designed and simulated a Luneburg lens[6] (see fig.1). We conceive thin and thick flat GRIN lenses[7]. For the sake, we engineer the equi-frequency curves which convey the dispersion properties of photonic crystals. Our aim is to go further up to the optical domain. The experimental evidence of such devices is an end in itself because it is a technological challenge to fabricate such GPC. Nevertheless, we will investigate the great variety of applications of GPC flat lens, which concerns Photonic Integrated Circuits, Lab on Chip, optical pumping of organic materials, OLED, biophotonics, fluorescence of cells, etc.

    PhD work plan

    GPC devices will be designed, fabricated and characterised at the Centre de Nanosciences et Nanotechnologies (C2N). This work will concern numerical simulation and optical design, nanotechnological processes and optical characterisation. These devices will operate at telecommunication wavelengths (1,55 μm). The Silicium On Insulator (SOI) channel of the C2N will be involved, because “state of the art" photonic crystal -based devices have already been fabricated in its clean-room [8]. These devices require the technological mastery of the position, of the size and of the shape of the patterns, which is adapted for the realisation of GPC devices. The size of the patterns of these latter is of several tens of nanometers, which will be challenging. The devices will be also characterised at the C2N. GPC devices operating in the near infrared (NIR) spectrum will also investigated (from 1 to 20μm) because, in this domain, lies a lot of molecular signatures, which is fruitful for NIR spectroscopy, chemical sensing, polluant detection, etc. 

          

     

    Fig. 1: Right : Focusing by a GPC GRIN flat lens[3] ; left : focusing by a Luneburg lens[6] 

    Bibliography

    [1]    Éric Akmansoy, Emmanuel Centeno, Kevin Vynck, David Cassagne, and Jean-Michel Lourtioz, Appl. Phys. Lett. 92, 133501 (2008) 

    [2]    Predrag Milojkovic, Stefanie Tompkins, Ravindra Athale, Gradient Index Optics, Optical Engineering, November 2013/Vol. 52(11), p. 112101-1 

    [3]    F. Gaufillet, É. Akmansoy, Graded photonic crystals for graded index lens, Optics Communications, Volume 285, 2638 (2012). 

    [4]    F. Gaufillet, É. Akmansoy, Design of flat graded index lenses using dielectric Graded Photonic Crystals, Optical Materials, Vol. 47, 555-560 (2015) 

    [5]    F. Gaufillet and E. Akmansoy. Design and experimental evidence of a flat graded-index photonic crystal lens. Journal of Applied Physics, 114(8) :083105, 2013. 

    [6]    F. Gaufillet and E. Akmansoy. Graded photonic crystals for Luneburg lens, IEEE Photonics Journal, vol. 8, 11 (2016) 

    [7]    CVI Melles Griot. Gradient-Index Lenses – http://pdf.directindustry.com/pdf/cvi-melles-griot/gradient-index-lenses/12567-66963.html. 

    [8]    Z. Han, X. Checoury, D. Néel, S. David, M. El Kurdi, P. Boucaud, Optimized design for ultra-high Q silicon photonic crystal cavities, Optics Communications 283 (21) (2010) 4387 – 4391.

    fichier joint

    eric.akmansoy@u-psud.fr - 33-1-6915 4143

  • ['Photonique']

    (in french) Développement de composants grande surface à nanostructures résonantes pour systèmes de réalité augmentée


      Beatrice Dagens.

    (in french)

    L’objectif de la thèse est de concevoir et réaliser par un procédé bas coût une lame transparente de grande surface fonctionnalisée par des nanostructures résonantes. La lame présentera les propriétés optiques requises pour un système compact de réalité augmentée, telles que la fonction de lentille réfléchissante dans le visible, préservant la qualité de transparence du support. Le travail inclura la conception de métasurfaces permettant le contrôle local et spectral de l’amplitude et de la phase du front d’onde des signaux réfléchis, ainsi que le développement de la technologie de fabrication grande surface et la caractérisation des échantillons réalisés.

    mots clé: métasurfaces, nanotechnologie, plasmonique, nanorésonateurs

    followed PhD


    beatrice.dagens@c2n.upsaclay.fr - 0169157837

  • ['Photonique']

    All-Dielectric Metamaterials for Terahertz metadevices


      Eric Akmansoy.

    Centre de Nanosciences et nanotechnologies

     UMR 9001 du CNRS,

    université Paris-Sud, université Paris-Saclay

    91 405 Orsay – France

      

    PhD research proposal

    All-Dielectric Metamaterials for Terahertz metadevices

     Éric Akmansoy 

    Département Photonique

    __________________ 

     

    General framework

    Metamaterials have opened a new field in physics and engineering. Indeed, these artificial structured materials give rise to unnatural fascinating phenomena such as negative index, sub-wavelength focusing and cloaking. Metamaterials also exhibit near-zero refractive index [1]. These open a broad range of applications, from the microwave to the optical frequency domain. Metamaterials have now evolved towards the implementation of optical components[2]. 

    We consider All-Dielectric Metamaterials which are the promising alternative to metallic metamaterials, because they do not suffer from ohmic losses and consequently benefit of low energy dissipation and because they are of simple geometry. They consist of high permittivity dielectric resonators involving Mie resonances. We have experimentally demonstrated negative effective permeability and/or permittivity by the means of all-dielectric metamaterials [3]. Previously, we have also demonstrated a negative index all-dielectric metamaterial [4]. Recently, we have numerically demonstrated a metadevice, namely, a metalens that focuses an incident plane wave, is less than one and a half wavelength thick. Its focal length is only a few wavelength and the spot in the focal plane is diffraction - limited.[5]. We also study role of the coupling of the modes of Mie resonances in an all-dielectric metamaterial so as to achieve negative index at terahertz frequencies (see fig. 1)[6].

    Work Plan

    During this thesis, all dielectric metamaterials will be designed, fabricated and characterized for the terahertz range. Negative index will be studied in this frequency domain, which is a challenge. Various devices which will be investigated such as flat lens, gradient devices, etc. This work takes place within a group of scientists of different disciplines (chemists, material scientists, physicists). 

     

     

    Fig. 1: Spatial mode coupling : frequency of the first two modes of Mie resonances in function of the distance  between two resonators which is half the lattice period . The shaded area corresponds to negative value of the effective index . It evidences the mode degeneracy [6].

    Bibliography

    [1]    I. Liberal and N. Engheta, “Near-zero refractive index photonics,”  Nature Photonics, vol. 11, pp. 149 EP –, 03 2017.

    [2]    N. I. Zheludev and Y. S. Kivshar, “From metamaterials to metadevices,”  Nat Mater, vol. 11, pp. 917–924, 11 2012.

    [3]    T. Lepetit, E. Akmansoy, and J.-P. Ganne, “Experimental evidence of resonant effective permittivity in a dielectric metamaterial,” Journal of Applied Physics, vol. 109, no. 2, p. 023115, 2011.

    [4]    T. Lepetit, É. Akmansoy, and J.-P. Ganne, “Experimental measurement of negative index in an all-dielectric metamaterial,” Applied Physics Letters, vol. 95, no. 12, p. 121101 (, 2009.

    [5]    F. Gaufillet, S. Marcellin, and E. Akmansoy, “Dielectric metamaterial-based gradient index lens in the terahertz frequency range,” IEEE J Sel Top Quant, vol. 10. 1109/JSTQE. 2016. 2633825, 2017.

    [6]    S. Marcellin and É. Akmansoy, “Negative index and mode coupling in all-dielectric metamaterials at terahertz frequencies,” in 2015 9th International Congress on Advanced Electromagnetic Materials in Microwaves and Optics (Metamaterials), pp. 4–6, Sept 2015.

    fichier joint

    eric.akmansoy@u-psud.fr - 33-1-6915 4143

  • ['Photonique']

    Graded Photonic Crystals Devices for Graded Index Optics


      Eric Akmansoy.

      

    Centre de Nanosciences et nanotechnologies

     UMR 9001 du CNRS,

    université Paris-Sud, université Paris-Saclay

    91 405 Orsay – France

      

    PhD research proposal

    Graded Photonic Crystals Devices for Graded Index Optics

     Éric Akmansoy 

    Département Photonique

    __________________ 

     

    General framework

    On the one hand, Graded Photonic Crystals (GPC) allow to efficiently control the flow of light thanks to the shape of their photonic bands, which we verified by demonstrating a “photonic mirage” at wavelength scale[1]. In the other hand, GRaded INdex (GRIN) optics is undergoing a renewal because it allows to downsize optical systems, opening a new way to optical design[2]. But GRIN optics was limited by a lack of easy to implement fabrication techniques. Nanotechnology enables to efficiently fabricate photonic crystals, which we will implement to fabricate GPC for GRIN optics. 

    We are designing, numerically simulating and characterising GPC devices (see fig.1)[3, 4]. More specifically, we have conceived a GRIN flat lens which we have characterised in the microwave[5]. Recently, we have designed and simulated a Luneburg lens[6] (see fig.1). We conceive thin and thick flat GRIN lenses[7]. For the sake, we engineer the equi-frequency curves which convey the dispersion properties of photonic crystals. Our aim is to go further up to the optical domain. The experimental evidence of such devices is an end in itself because it is a technological challenge to fabricate such GPC. Nevertheless, we will investigate the great variety of applications of GPC flat lens, which concerns Photonic Integrated Circuits, Lab on Chip, optical pumping of organic materials, OLED, biophotonics, fluorescence of cells, etc.

    PhD work plan

    GPC devices will be designed, fabricated and characterised at the Centre de Nanosciences et Nanotechnologies (C2N). This work will concern numerical simulation and optical design, nanotechnological processes and optical characterisation. These devices will operate at telecommunication wavelengths (1,55 μm). The Silicium On Insulator (SOI) channel of the C2N will be involved, because “state of the art" photonic crystal -based devices have already been fabricated in its clean-room [8]. These devices require the technological mastery of the position, of the size and of the shape of the patterns, which is adapted for the realisation of GPC devices. The size of the patterns of these latter is of several tens of nanometers, which will be challenging. The devices will be also characterised at the C2N. GPC devices operating in the near infrared (NIR) spectrum will also investigated (from 1 to 20μm) because, in this domain, lies a lot of molecular signatures, which is fruitful for NIR spectroscopy, chemical sensing, polluant detection, etc. 

          

     

    Fig. 1: Right : Focusing by a GPC GRIN flat lens[3] ; left : focusing by a Luneburg lens[6] 

    Bibliography

    [1]    Éric Akmansoy, Emmanuel Centeno, Kevin Vynck, David Cassagne, and Jean-Michel Lourtioz, Appl. Phys. Lett. 92, 133501 (2008) 

    [2]    Predrag Milojkovic, Stefanie Tompkins, Ravindra Athale, Gradient Index Optics, Optical Engineering, November 2013/Vol. 52(11), p. 112101-1 

    [3]    F. Gaufillet, É. Akmansoy, Graded photonic crystals for graded index lens, Optics Communications, Volume 285, 2638 (2012). 

    [4]    F. Gaufillet, É. Akmansoy, Design of flat graded index lenses using dielectric Graded Photonic Crystals, Optical Materials, Vol. 47, 555-560 (2015) 

    [5]    F. Gaufillet and E. Akmansoy. Design and experimental evidence of a flat graded-index photonic crystal lens. Journal of Applied Physics, 114(8) :083105, 2013. 

    [6]    F. Gaufillet and E. Akmansoy. Graded photonic crystals for Luneburg lens, IEEE Photonics Journal, vol. 8, 11 (2016) 

    [7]    CVI Melles Griot. Gradient-Index Lenses – http://pdf.directindustry.com/pdf/cvi-melles-griot/gradient-index-lenses/12567-66963.html. 

    [8]    Z. Han, X. Checoury, D. Néel, S. David, M. El Kurdi, P. Boucaud, Optimized design for ultra-high Q silicon photonic crystal cavities, Optics Communications 283 (21) (2010) 4387 – 4391.

    fichier joint

    eric.akmansoy@u-psud.fr - 33-1-6915 4143

  • ['Photonique']

    Subwavelength silicon photonic nanostructures for applications in the near-IR and mid-IR


      Carlos Alonso-Ramos.

    Driven by the impressive development in the nanofabrication technologies and the nanoscale engineering, silicon photonics has rapidly become the platform of choice for on-chip integration of high performing photonic devices. At the beginning, these photonic circuits mainly targeted the realization of ultra-wideband transceivers for datacom applications, e.g. in big datacenters. However, this enormous technology development has opened new opportunities for Si photonics beyond datacom, with a growing interest in sensing [1], microwave photonics [2] and quantum photonics [3] applications. Aiming to meet the requirements of these envisioned applications, Si photonics is expanding its frontiers by exploring wider wavelength ranges and new physical phenomena. On the one hand, a great effort is being devoted to increase the operation wavelength from the near-infrared towards the mid-infrared, thus covering the full Si transparency window, between 1.1 mm and 8 mm wavelengths [4,5]. This new wavelength range holds the promise to create exciting new opportunities, e.g. in absorption spectroscopy and nonlinear photonics. On the other hand, light-sound (photon-phonon) interactions in Si waveguides is raising a growing interest [6,7]. Specifically, stimulated Brillouin scattering is being investigated, targeting key functionalities in all-optical circuits and microwave photonics signal processing.

    In this context of new applications, new wavelength ranges and new physical phenomena, researches in sub-wavelength engineering of Si structures can play a key role. Patterning Si with features smaller than half of the wavelength (well within the capabilities of standard large volume fabrication processes) has proven to be a simple and powerful tool to tailor material properties [8,9]. This innovative approach releases new degrees of freedom that allow unprecedented flexibility in the design of light-matter interactions, chromatic dispersion and light propagation in general. Indeed, sub-wavelength engineering has already been used to demonstrate stat-of-the-art performance in several key devices, including low loss waveguides and crossings, micro-resonators, fiber-to-chip grating couplers and power splitters.

    The goal of this PhD is to develop new types of sub-wavelength nanostructured silicon photonics devices, targeting ultra-wideband operation and enhanced light-matter interactions.

    This work will be done in the framework of the National ANR project MIR-Spec, in close collaboration with ST-Microelectronics (www.st.com) and start-up mirSense (www.mirsense.com)

    The research activity will include:

    - Theoretical study of sub-wavelength engineered devices (using commercial software) extract main relationships between geometrical parameters and properties of the waveguide.

    - Fabrication of nano-structured Si photonics devices in our clean-room facilities.

    - Experimental characterization of linear and nonlinear properties of developed devices.

    followed PhD

    fichier joint

    carlos.ramos@u-psud.fr - 0169156306

  • ['Photonique']

    (in french) Reconfigurable photonic devices for mid IR photonic integrated circuits


      Delphine Marris-Morini.

    (in french)

    Mid-infrared (mid-IR) integrated photonics (i.e. between 2 and 20µm) is actually a subject of increased emphasis, with a strong potential to revolutionize different application fields. As an example mid IR spectroscopy is a nearly universal way to identify chemical and biological substances, as most of the molecules have their vibrational and rotational resonances in this wavelength range. Commercially available mid-IR systems are based on bulky and expensive equipment, while lots of efforts are now devoted to the reduction of their size down to chip-scale dimensions. The demonstration of mid-IR photonic circuits on silicon chips would benefit from reliable and high-volume fabrication to offer high performance, low cost, compact, low weight and power consumption photonic circuits, which is particularly interesting for mid-IR spectroscopic sensing systems that need to be portable and low cost. Mid-IR photonic circuits on silicon chips can also have important applications for free space telecommunications or military applications.

    In this context, we develop a new route for the development of chip-scale integrated circuits on silicon for the mid-IR wavelength range, based on Ge-rich SiGe materials. We recently demonstrated the strong potential of this platform for broadband operation in the mid-IR. We also studied nonlinear properties of Ge-rich SiGe waveguides, showing that band-gap engineering can be used to tune the non-linear effects and to exploit diverse phenomena based on nonlinear effects.

    As a next step we would like to investigate the possibility to command electrically the properties of these integrated devices (by applying an electrical voltage). While electro-optical control of Si based devices in the near IR has been largely studied, very little work has been reported up to now in the mid-IR wavelength range. The main idea will be to use refractive index/absorption coefficient variations by free carrier concentration variations, in order to develop reconfigurable devices.

    Targeted devices cover (i) optical modulator based on ring resonator/Mach Zehnder interferometer for synchronous detection systems, (ii) reconfigurable spectrometers to finely tune the spectral response of an on-chip spectroscopic detection platform.

    Besides these objectives, the development of active devices in the mid-IR can also have a strong impact for other application such as free space communications.

    The goal of this PhD project will be to develop electrically-controlled optical devices based on Ge-rich SiGe waveguides, from 5 to 8 µm wavelength.

    The research activity will include:

                    - theoretical study and electro/optical simulations (using commercial software) to evaluate the key metrics for tuning the optical properties of the waveguide modes

                    - clean-room fabrication based on classical fabrication process (lithographie, etching, …)

    - experimental characterizations using mid-IR optical bench developed within the group

     

    The work is done in the framework of the ERC INsPIRE project, in a strong collaboration with Giovanni Isella’s group (L-Ness lab (Politecnico di Milano)).

    During his PhD, the student will be actively involved in the current research activity of the group, collaborating with PhD students, postdocs and researchers of different research backgrounds and nationalities.

     

     VALUED QUALITIES IN THE STUDENT

    - Curiosity for novel research experiences and fields.

    - Creativity and pro-activity in the search for innovative solutions and approaches.

    - Capability to communicate and share results in a multidisciplinary and multi-nationality environment.

     

    BIBLIOGRAPHY RELATED TO THE TOPIC

    [1] J.M. Ramirez, V. Vakarin, C. Gilles, J. Frigerio, A. Ballabio, P. Chaisakul, X. Le Roux, C. Alonso-Ramos, G. Maisons, L. Vivien, M. Carras, G. Isella, D. Marris-Morini, “Low-loss Ge-rich Si0.2Ge0.8 waveguides for mid-infrared photonics”, Optics Letters 42 (1) 105 (2017).

    https://hal.archives-ouvertes.fr/hal-01430021

     

    [2] J.M. Ramirez, V. Vakarin, J. Frigerio, P. Chaisakul, D. Chrastina, X. Le Roux, A. Ballabio, L. Vivien, G. Isella, D. Marris-Morini, “Ge-rich graded-index Si1-xGex waveguides with broadband tight mode confinement and flat anomalous dispersion for nonlinear mid-infrared photonics”, Optics Express 25 (6) 6561 (2017) 

    https://doi.org/10.1364/OE.25.006561

     

    [3] V. Vakarin, J-M. Ramirez, J. Frigerio, A. Ballabio, X. Le Roux, Q. Liu, D. Bouville, L. Vivien, G. Isella, D. Marris-Morini, “Ultra-wideband Ge-rich silicon germanium integrated Mach–Zehnder interferometer for mid-infrared spectroscopy” Optics Letters  Vol. 42 n°17, 3482-3485 (2017)

    https://hal.archives-ouvertes.fr/hal-01579360

    fichier joint

    delphine.morini@u-psud.fr - 0169157852

  • ['Photonique']

    Ultrathin III-V/Si tandem solar cells


      Stéphane Collin.

    III-V-based solar cells are the best candidate for high-efficiency tandem solar cells on silicon. Record efficiencies (>33%) have been obtained with tandem fabricated by direct wafer bonding of III-V on Si. The main drawback of this technology is the cost.

    The goal of this project is to develop a new architecture for ultrathin III-V/Si tandem solar cells, and to use processes compatible with low-cost fabrication. A multi-functional nanostructured layer will be designed and inserted between III-V and Si in order to facilitate the bonding of III-V layers on Si, transport of carriers, and light trapping for thickness reduction. The project will take place at IPVF and C2N, in close collaboration with the Fraunhofer ISE and the Collège de France. The PhD grant is funded by EDF.


    stephane.collin@c2n.upsaclay.fr - +33 1 6963 6145

  • ['Microsyst']

    Miniaturized artificial microfluidic lung


      Anne-Marie Haghiri-Gosnet and Gilgueng Hwang.

    Context: End-stage lung diseases may result in death either by oxygenation and carbon dioxide exchange insufficiency or by right heart failure. Despite recent dramatic improvements in the medical management of these diseases, lung transplantation remains ultimately the only therapeutic option. However, shortage of donor organs and long waiting times on list make this treatment only available for few patients. The aim of “BIOART LUNG 2020” RHU-ANR French project, coordinated by Professor Olaf Mercier of the Center of Thoracic Surgery of the Hospital Marie-Lannelongue is to develop a novel bio-artificial microfluidic lung as a durable method of replacing lung function in patients with end-stage refractory lung disease.

     

    The position: This postdoctoral position will focus first on blood flow measurements under pressure inside the vascular network and secondly on the study of the oxygenation function of a tri-layer microfluidic device. Based on a new bonding protocol allowing perfect integration of a thin membrane between the blood capillaries and the air chamber, the post-doc will study the role of the membrane structuration on the oxygenation capacity of the system.  He (She) will work in close collaboration with the team of Professor G. Uzan (Hospital P. Brousse) to develop a robust protocol for endothelial cells in the vascular network for minimizing shear stress. This project mixes micro/nanotechnology based on innovative flexible polymers, microfluidics under high flow conditions and cell culture under stress conditions with a perfect balance between experimental science and fluidic simulations. The post-doc will work inside the microfluidics team and directly with 3 researchers (G. Hwang, J. Gamby and A-M. Haghiri-Gosnet).

     

    The candidate:  We seek open-minded and curious candidates with strong expertise in different fields: microfabrication, microfluidics, engineering and biology with interest in multidisciplinary research. With a PhD in the field of microfluidics and an engineering vision, he should also express a clear taste towards experimental work coupled with COMSOL simulation. Finally, an additional expertise in cell culture within fluidic devices will be a strong asset.

     

    The net salary:  2080€/month for a young post-doc (just PhD graduated) or 2915€/month for a CDD researcher with an experience of 2 years in research.

     

    The group: The BIOSYS microfluidics team at C2N (https://www.c2n.universite-paris-saclay.fr/fr/recherche/mnbf/biosys/) has expertise in micro and nanofluidics [Lab Chip 11 (2011) 785-804], high performance separation techniques [Langmuir, 31(37) (2015) 10318-10325], biosensing [Biomicrofluidics 10 (2016) 014115], nanofabrication (nanoimprint and 3D Lithography [Nanoscale 8 (2016) 15479]), and microswimmers [5].

    The lab: The Center of Nanosciences and Nanotechnology is one of the 6 nanofabrication labs in France with a state-of-the-art clean room in a very nice working environment in the Paris area.

     

    Contact: You should send CV and 3 recommendations

    to Anne-Marie Haghiri-Gosnet and Gilgueng Hwang

    at anne-marie.haghiri@c2n.upsaclay.fr and gilgueng.hwang@c2n.upsacaly.fr

    fichier joint

    anne-marie.haghiri@c2n.upsaclay.fr - +(33) 1 69 63 61 22

  • ['Photonique']

    Non-linear dynamics of nano-optomechanical resonators


      Rémy Braive.

    Nonlinear dynamics in optomechanical resonator can cause both the optical and the mechanical modes to evolve from periodic to chaotic oscillations. Despite recent progress and growing interest on nonlinear dynamical effects occurring in Nano-OptoElectroMechanical systems (NOEMs), optomechanical chaos and stochastic resonance remain largely unexplored experimentally in such research field. Further experimental and theoretical studies will not only substantially deepen our understanding of noise-induced processes in non-linear NOEMs but also cast the bases for their use in noise-aided high-precision measurements and noise-assisted detection of weak signals.

    fichier joint

    remy.braive@c2n.upsaclay.fr - 01 69 63 60 49

  • ['Photonique']

    Nano-optomechanics for time-frequency metrology and microwave photonics


      Rémy Braive.

    The photonic clock architecture will rely on an integrated high-quality optomechanical resonator, namely a photonic crystal defect cavity, in order to achieve very stable oscillation in the GHz range, where the lack of good quality and miniaturized sources is a severe issue. Thanks to the strong reduction of the oscillator dimensions down to nanoscale, the resonator will sustain mechanical modes strongly coupled to light up to 3-5 GHz, directly at the operating frequency of interest for optoelectronic microwave oscillators and metrology applications.

    fichier joint

    remy.braive@c2n.upsaclay.fr - 01 69 63 60 49