97 research outputs found
InterféromÚtre de type Mach-Zehnder en silicium poreux : application aux biocapteurs
International audienceDans cette étude est présentée la réalisation et la caractérisation d'un guide d'ondes optique enterré et anti-résonant à base de silicium poreux. Ce guide d'ondes est intégré dans une structure interférométrique de type Mach-Zehnder qui sera utilisée pour une application de biodétection. Les simulations et les caractérisations optiques montrent clairement le guidage monomode ainsi que le caractÚre anti-résonant des guides d'ondes enterrés
Functionalization control of porous silicon optical structures using reflectance spectra modeling for biosensing applications
International audienceModeling and experimental reflectance spectra of porous silicon single layers at different steps of functionalization and protein grafting process are adjusted in order to determine the volume fraction of the biomolecules attached to the internal pore surface. This method is applied in order to control the efficiency of the chemical functionalization process of porous silicon single layers. Using results from single porous silicon layer study, theoretical microcavity is simulated at each step of the functionalization process. The calculated reflectance spectrum is in good agreement to the experimental one. Therefore the single layers study can be applied to multilayer structures and can be adapted for other optical structures such as waveguides, interferometers for biosensing applications
Buried Anti Resonant Reflecting Optical Waveguide based on porous silicon material for an integrated Mach Zehnder structure
International audienceA buried Anti Resonant Reflecting Optical Waveguide for an integrated Mach Zehnder structure based on porous silicon material is achieved using a classical photolithography process. Three distinct porous silicon layers are then elaborated in a single step, by varying the porosity (thus the refractive index) and the thickness while respecting the anti-resonance conditions. Simulations and experimental results clearly show the antiresonant character of the buried waveguides. Significant variation of the reflectance and light propagation with different behavior depending on the polarization and the Mach Zehnder dimensions is obtained. Finally, we confirm the feasibility of this structure for sensing applications
Towards a biosensor based on Anti Resonant Reflecting Optical Waveguide fabricated from porous silicon.
International audienceRecently, we demonstrated that Anti Resonant Reflecting Optical Waveguide (ARROW) based on porous silicon (PS) material can be used as a transducer for the development of a new optical biosensor. Compared to a conventional biosensor waveguide based on evanescent waves, the ARROW structure is designed to allow a better overlap between the propagated optical field and the molecules infiltrated in the porous core layer and so to provide better molecular interactions sensitivity. The aim of this work is to investigate the operating mode of an optical biosensor using the ARROW structure. We reported here an extensive study where the antiresonance conditions were adjusted just before the grafting of the studied molecules for a given refractive index range. The interesting feature of the studied ARROW structure is that it is elaborated from the same material which is the porous silicon obtained via a single electrochemical anodization process. After oxidation and preparation of the inner surface of porous silicon by a chemical functionalization process, bovine serum albumin (BSA) molecules, were attached essentially in the upper layer. Simulation study indicates that the proposed sensor works at the refractive index values ranging from 1.3560 to 1.3655. The experimental optical detection of the biomolecules was obtained through the modification of the propagated optical field and losses. The results indicated that the optical attenuation decreases after biomolecules attachment, corresponding to a refractive index change Înc of the core. This reduction was of about 2 dB/cm and 3 dB/cm for Transverse Electric (TE) and Transverse Magnetic (TM) polarizations respectively. Moreover, at the detection step, the optical field was almost located inside the core layer. This result was in good agreement with the simulated near field profiles
Micro-resonators based on integrated polymer technology for optical sensing
International audienceResearch on sensors has experienced a noticeable development over the last decades especially in label free optical biosensors. However, compact sensors without markers for rapid, reliable and inexpensive detection of various substances induces a significant research of new technological solutions. The context of this work is the development of a sensor based on easily integrated and inexpensive micro-resonator (MR) component in integrated optics, highly sensitive and selective mainly in the areas of health and food. In this work, we take advantage of our previous studies on filters based on micro-resonators (MR) to experiment a new couple of polymers in the objective to use MR as a sensing function. MRs have been fabricated by processing SU8 polymer as core and PMATRIFE polymer as cladding layer of the waveguide. The refractive index contrast reaches 0.16 @ 1550 nm. Sub-micronic ring waveguides gaps from 0.5 to 1 ”m have been successfully achieved with UV (i-line) photolithography. This work confirms our forecasts, published earlier, about the resolution that can be achieved. First results show a good extinction coefficient of ~17 dB, a quality factor around 104 and a finesse of 12. These results are in concordance with the theoretical study and they allow us to validate our technology with this couple of polymers. Work is going on with others lower cladding materials that will be used to further increase refractive index contrast for sensing applications
Optical study of annealed cobalt-porous silicon nanocomposites
International audienceWe report Raman and photoluminescence studies of cobalt-porous silicon nanocomposites (PS/Co). Cobalt was introduced in porous silicon (PS) by immersion method using CoCl2 aqueous solution. The presence of cobalt in PS matrix was identified by FTIR spectroscopy and EDX analyses. The Raman spectroscopy revealed the presence of Si bonded to cobalt oxide in PS/Co. We discuss also the Raman spectra of PS and PS/Co samples under different annealing temperatures ranging from room temperature (RT) to 600 °C. The optical properties of PS and PS/Co were studied by photoluminescence (PL). The highest PL intensity was observed for an immersion time of 60 min. For long duration, the deposited cobalt quantity acts as energy trap and promotes the non-radiative energy transfer; it is the autoextinction phenomenon. We have studied also the effect of the annealing temperature on the PL of both PS and PS/Co samples. For PS, the annealing process leads to a rapid oxidation of the Si nanocrystallites (nc-Si). In the case of PS/Co sample, two different mechanisms are proposed; one is the desorption of Si-Hx(x=2,3) with the formation of cobalt oxide for annealing temperature less than 450 °C which causes the increasing of PL intensity and the stability of PL energy, the other mechanism is the transformation of the porous silicon to silica at high temperatures View the MathML source(â»450°C) which leads to the decreasing of the PL intensity and the blue shift of the PL curve
Capteur en Optique Intégrée à Base de Verres de Chalcogénures pour la Détection de Polluants dans le Moyen-Infrarouge
National audienceLe Moyen Infra-Rouge (MIR) est la rĂ©gion spectrale comprise entre 3 et 20 ”m. Cette gamme de longueurs dâonde est connue pour contenir des transitions vibrationnelles fondamentales caractĂ©ristiques dâespĂšces molĂ©culaires en phase liquide ou gazeuse. De nombreuses substances telles que le toluĂšne, le mĂ©thanol, lâĂ©thanol, lâacĂ©tone, le glucose, le dioxyde de carbone peuvent ĂȘtre caractĂ©risĂ©es par spectroscopie infrarouge grĂące Ă leur signature spectrale dâabsorption. Cette technique est ainsi une des plus appropriĂ©es parmi les techniques classiques dâanalyse pour lâidentiïŹcation et la caractĂ©risation structurelle des espĂšces molĂ©culaires. Les disponibilitĂ©s rĂ©centes de plateformes optiques prĂ©sentant de faibles pertes de propagation et de sources Ă©mettant dans le MIR, notamment des QCL ont Ă©tĂ© la clĂ© du dĂ©veloppement dâĂ©tudes destinĂ©es Ă la rĂ©alisation de capteurs optiques fonctionnant dans la gamme spectrale du MIR. Par ailleurs, les capteurs en optique intĂ©grĂ©e sont devenus une excellente alternative pour la dĂ©tection in situ car ils prĂ©sentent certains avantages sur les autres types de capteurs, tels que l'intĂ©gration des Ă©lĂ©ments dans un dispositif compact. Ils sont actuellement utilisĂ©s dans divers domaines sociĂ©taux tels que la santĂ©, la dĂ©fense et lâenvironnement.Il existe diffĂ©rents matĂ©riaux transparents dans le MIR (le silicium, le germanium, lâarsĂ©niure de galium ou encore les verres de chalcogĂ©nures) susceptibles de constituer la plateforme optique de ces capteurs intĂ©grĂ©s. Les verres de chalcogĂ©nures (ChGs) sont des matĂ©riaux semi-conducteurs composĂ©s par les Ă©lĂ©ments du groupe VIa (sĂ©lĂ©nium (Se), tellure (Te) ou soufre (S)). Ils forment des verres lorsquâils sont mĂ©langĂ©s Ă un ou plusieurs autres Ă©lĂ©ments tels que le galium (Ga), le germanium (Ge), lâantimoine (Sb), le silicium (Si) ou le phosphore (P). Ces verres de ChGs se distinguent par leur transparence Ă©tendue dans lâinfrarouge: certaines compositions transmettent jusquâĂ 20 ”m. Typiquement, leur transmission dans le MIR a Ă©tĂ© caractĂ©risĂ©e jusquâĂ 12 ”m pour les sulfures, Ă 16 ”m pour les sĂ©lĂ©niures et Ă 18 ”m pour les tellures. Certains travaux ont montrĂ© la fabrication et la caractĂ©risation de capteurs optiques dans le proche infra-rouge. Dans cet article, nous proposons de tirer profit de la transparence Ă©levĂ©e de ces matĂ©riaux dans le MIR pour fabriquer un capteur spectroscopique Ă onde Ă©vanescente fonctionnant dans cette gamme spectrale.
Technologie d'optique intégrée au laboratoire Foton
National audienceCet article résume le panorama de l'état de l'art des technologies d'optique intégrée maitrisées au laboratoire Foton (SystÚmes Photoniques) axé sur l'optique intégrée polymÚre active et passive, les guides en silicium et silice poreuse pour la réalisation de capteurs biologiques, ainsi que les applications des guides en verres spéciaux étudiés en collaboration avec d'autres laboratoires
Technologie d'optique intégrée polymÚre au laboratoire FOTON
National audienceCet article résume le panorama de l'état de l'art des technologies d'optique intégrée polymÚre maitrisées au laboratoire Foton (SystÚmes Photoniques) et qui sont axées sur des circuits optiques actifs et passifs. Les objectifs sont orientés vers un fort confinement du mode de propagation, la génération d'effets non linéaires, l'hybridation avec d'autres matériaux et la réduction des pertes (couplage et propagation)
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