BAUDET Emeline

The objective of this study is to demonstrate the successful functionalization of the surface of a chalcogenide infrared waveguide with the ultimate goal of developing an infrared micro-sensor device. First, a polyisobutylene coating was selected by testing its physico-chemical compatibility with a Ge-Sb-Se selenide surface. To simulate the chalcogenide platform infrared sensor, the detection of benzene, toluene, and ortho-, meta- and para-xylenes was efficaciously performed using a polyisobutylene layer spin-coated on 1 and 2.5 mu m co-sputtered selenide films of Ge28Sb12Se60 composition deposited on a zinc selenide prism used for attenuated total reflection spectroscopy. The thickness of the polymer coating was optimized by attenuated total reflection spectroscopy to achieve the highest possible attenuation of water absorption while maintaining the diffusion rate of the pollutant through the polymer film compatible with the targeted in situ analysis. Then, natural water, i.e., groundwater, wastewater, and seawater, was sampled for detection measurement by means of attenuated total reflection spectroscopy. This study is a valuable contribution concerning the functionalization by a hydrophobic polymer compatible with a chalcogenide optical sensor designed to operate in the mid-infrared spectral range to detect in situ organic molecules in natural water.

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Despite the renewed interest in rare earth-doped chalcogenide glasses lying mainly in mid-infrared applications, a few comprehensive studies so far have presented the photoluminescence of amorphous chalcogenide films from visible to mid-infrared. This work reports the fabrication of luminescent quaternary sulfide thin films using radio-frequency sputtering and pulsed laser deposition, and the characterization of their chemical composition, morphology, structure, refractive index and Er photoluminescence. The study of ErI level lifetimes enables developing suitable deposition parameters. the dependency of composition, structural and spectroscopic properties on deposition parameters provides a way to tailor the RE-doped thin film properties. The surface roughness is very low for both deposition methods, ensuring reasonable propagation optical losses. The effects of annealing on the sulfide films spectroscopy and lifetimes were assessed. PLD appears consistent composition-wise, and largely independent of the deposition conditions, but radiofrequency magnetron sputtering seems to be more versatile, as one may tailor the film properties through deposition parameters manipulation. The luminescence via rare earth-doped chalcogenide waveguiding micro-structures might find easy-to-use applications concerning telecommunications or on-chip optical sensors for which luminescent sources or amplifiers operating at different wavelengths are required.

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Amorphous Ge-Sb-Se thin films were fabricated by a rf-magnetron co-sputtering technique employing the following cathodes GeSe2, Sb2Se3, and Ge28Sb12Se60. The influence of the composition, determined by energy-dispersive X-ray spectroscopy, on the optical properties was studied. Optical properties were analyzed based on variable angle spectroscopic ellipsometry and UV-Vis-NIR spectrophotometry. The results show that the optical bandgap range 1.35-2.08 eV with corresponding refractive index ranging from 3.33 to 2.36 can be reliably covered. Furthermore, morphological and topographical properties of selenide-sputtered films studied by scanning electron microscopy and atomic force microscopy showed a good quality of fabricated films. In addition, structure of the films was controlled using Raman scattering spectroscopy. Finally, irreversible photoinduced changes by means of change in optical bandgap energy and refractive index of co-sputtered films were studied revealing the photobleaching effect in Ge-rich films when irradiated by near-bandgap light under Ar atmosphere. The photobleaching effect tends to decrease with increasing antimony content.

Pulsed laser deposition was used to prepare amorphous thin films from (GeSe2)(100-x)(Sb2Se3)(x) system (x=0, 5, 10, 20, 30, 40, 50, and 60). From a wide variety of chalcogenide glass-forming systems, Ge-Sb-Se one, especially in thin films form, already proved to offer a great potential for photonic devices such as chemical sensors. This system has a large glass-forming region which gives the possibility to adjust the chemical composition of the glasses according to required physical characteristics. The chemical composition of fabricated thin films was analyzed via X-ray photoelectron spectroscopy (XPS) and compared to energy dispersive spectroscopy (EDS) data. The results of both techniques agree well a small deficiency in chalcogen element and an excess of antimony was found. The structure of as-deposited thin films has been investigated by XPS. The presence of the two main structural units, [GeSe4] and [SbSe3] proposed by Raman scattering spectroscopy data analysis, was confirmed by XPS. Moreover, XPS core level spectra analysis revealed the presence of M-M bonds (M=Ge, Sb) in (Ge,Sb)-Ge-(Se)(3) and (Ge,Sb)-Sb-(Se)(2) entities that could correspond to Ge-based tetrahedra and Sb-based pyramids where one of its Se atoms at corners is substituted by Ge or Sb ones. The content of depicted M-M bonds tends to increase with introduction of antimony in the amorphous network of as-deposited thin films from x=0 to x=40 and then it decreases. XPS analysis of as-deposited thin films shows also the presence of the (Ge,Sb)-Se-(Ge,Sb) and Se-Se-(Ge,Sb) entities.

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A compact amplifier based on chalcogenide Pr3+-doped micro-disk coupled to two ridge waveguides is designed and refined by means of a home-made computer code. The gain G ≈ 7.9 dB is simulated for a Pr3+ concentration of 10 000 ppm, input signal power of -30 dBm at the wavelength 4.7 μm and input pump power of 50 mW at the wavelength 1.55 μm. In the laser behavior, i.e. without input signal, the maximum slope efficiency S = 8.1 × 10-4 is obtained for an input pump power of 2 mW. This value is about six times higher than that simulated for an optimized erbium-doped micro-disk. © 2017 Optical Society of America.

AsxTe100-x amorphous thin films were fabricated by a pulsed laser deposition technique with the aim of finding photostable layers in as-deposited but preferably in relaxed (annealed) state. Photostability was studied in terms of the films' stability of refractive index and bandgap under nearbandgap light irradiation. As40Te60 and As50Te50 layers were found to be photostable in both as-deposited as well as relaxed states. Moreover, As50Te50 layers present the lowest surface roughness. These characteristics make pulsed-laser-deposited As50Te50 thin films promising for applications in nonlinear optics. (C) 2017 Optical Society of America.

We present a reliable and original experimental technique based on the analysis of beam self-trapping to measure ultrafast optical nonlinearities in planar waveguides. The technique is applied to the characterization of Ge–Sb–Se chalcogenide films that allow Kerr induced self-focusing and soliton formation. Linear and nonlinear optical constants of three different chalcogenide waveguides are studied at 1200 and 1550 nm in femtosecond regime. Waveguide propagation loss and two photon absorption coefficients are determined by transmission analysis. Beam broadening and narrowing results are compared with simulations of the nonlinear Schrödinger equation solved by BPM method to deduce the Kerr n2 coefficients. Kerr optical nonlinearities obtained by our original technique compare favorably with the values obtained by Z-scan technique. Nonlinear refractive index as high as (69±11)×10−18m2∕W is measured in Ge12.5Sb25Se62.5 at 1200 nm with low nonlinear absorption and low propagation losses which reveals the great characteristics of our waveguides for ultrafast all optical switching and integrated photonic devices. © 2017 Elsevier B.V.

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Laser desorption ionization using time-of-flight mass spectrometer afforded with quadrupole ion trap was used to study As(2)Ch(3) (Ch = S, Se, and Te) bulk chalcogenide materials. The main goal of the study is the identification of species present in the plasma originating from the interaction of laser pulses with solid state material. The generated clusters in both positive and negative ion mode are identified as 10 unary (S (p) (+/-) and As (m) (+/-) ) and 34 binary (As (m) S (p) (+/-) ) species for As2S3 glass, 2 unary (Se (q) (+/-) ) and 26 binary (As (m) Se (q) (+/-) ) species for As2Se3 glass, 7 unary (Te (r) (+/-) ) and 23 binary (As (m) Te (r) (+/-) ) species for As2Te3 material. The fragmentation of chalcogenide materials was diminished using some polymers and in this way 45 new, higher mass clusters have been detected. This novel approach opens a new possibility for laser desorption ionization mass spectrometry analysis of chalcogenides as well as other materials.

The unique properties of amorphous chalcogenides such as wide transparency in the infrared region, low phonon energy, photosensitivity and high linear and nonlinear refractive index, make them prospective materials for photonics devices. The important question is whether the chalcogenides are stable enough or how the photosensitivity could be exacerbated for demanded applications. Of this view, the Ge-Sb-Se system is undoubtedly an interesting glassy system given the antinomic behavior of germanium and antimony with respect to photosensitivity. The amorphous Ge-Sb-Se thin films were fabricated by a rf-magnetron co-sputtering technique employing the following cathodes: GeSe2,Sb2Se3 and Ge28Sb12Se60. Radio-frequency sputtering is widely used for film fabrication due to its relative simplicity, easy control, and often stoichiometric material transfer from target to substrate. The advantage of this technique is the ability to explore a wide range of chalcogenide film composition by means of adjusting the contribution of each target. This makes the technique considerably effective for the exploration of properties mentioned above. In the present work, the influence of the composition determined by energy-dispersive X-ray spectroscopy on the optical properties was studied. Optical bandgap energy E-g(opt) was determined using variable angle spectroscopic ellipsometry. The morphology and topography of the selenide sputtered films was studied by scanning electron microscopy and atomic force microscopy. The films structure was determined using Raman scattering spectroscopy.

No summary available.

A theoretical study of evanescent optical sensor for multipurpose detection in the Mid-Infrared of gases and pollutants in water is presented in this paper. The opto-geometrical parameters of the transducers - ridge waveguides - have been optimized in order to obtain the highest evanescent power factor for monomodal propagation in the Mid-Infrared. The highest sensitivity has been obtained for a configuration with an optimal length of waveguide L-ops = 4.3 cm for intrinsic propagation loss equal to 1 dB/cm. Then a spiral waveguide configuration is suggested to obtain this optical length path in a monolithic structure. A numerical example is also included using a ridge waveguide based on chalcogenide glasses (GeSbSe). In case of gas detection, a generic calculation of the minima concentrations to be detected as a function of the molar absorption for any working wavelength is presented. Extremely low limits of detection can be achieved due to the strong absorption coefficients of gases and chemical species in the Mid-Infrared spectral range, 268 ppb in case of carbon dioxide at lambda =4.3 p.m, 1.848 ppm and 781 ppb for methane at lambda=3.31 pm and at lambda=7.66 pm respectively. For the pollutants detection in water, an improvement of the integrated structure has been proposed to avoid water absorption in this spectral region by deposing a polymer (PIB) as waveguide superstrate, thus the limit of detection for toluene is 26 ppb at lambda=6.68 pm. These concentration minima that could be detected by the Mid-IR sensor are lower than the threshold limit values determined in the international environmental and health standards. Hence this integrated optical sensor may be considered as an attractive support tool in monitoring environmental and health fields. (C) 2016 Elsevier B.V. All rights reserved.

Mid-Infrared (2-20 µm) spectroscopic techniques are widely used to identify chemicals substances, allowing quantitative real-time measurements in gases, liquids and solids. The current trend heads to the miniaturization of optical sensors, replacing bulky laboratory instruments (FTIR, monochromators, ATR etc.) by lab-on-chip devices providing portability, mechanical stability, immunity to electromagnetic noise and the potential for batch production. In recent years, optical integrated devices have been fabricated using different technologies such as GaAs, Si, Si3N4 and Ge. Chalcogenide glasses have also emerged as good candidates to manufacture Mid-Infrared photonic integrated circuits thanks to their ability to be deposited as thin films, their broad transparency (up to 20 µm), their potential to be doped with rare earth ions and their refractive index tunability obtained by varying glass composition.

A selenide integrated platform working in the mid-infrared was designed, fabricated and optically characterized at 7.7 μm. Ge-Sb-Se multilayered structures were deposited by RF magnetron sputtering. Using i-line photolithography and fluorine-based reactive ion etching, ridge waveguides were processed as Y-junction, spiral and S-shape waveguides. Single-mode optical propagation at 7.7 μm was observed by optical near-field imaging and optical propagation losses of 2.5dB/cm are measured. Limits of detection of 14.2 ppm and 1.6 ppm for methane and nitrous oxide, respectively, could be potentially measured by using this platform as an evanescent field sensor. Hence, these technological, experimental and theoretical results represent a first step towards the development of an integrated optical sensor operating in the mid-infrared wavelength range. © 2016 Optical Society of America.

We present a new experimental technique based on the analysis of beam self-action to measure optical nonlinearity in planar waveguides. This technique is applied to analyze the nonlinear properties of slab chalcogenide waveguides that can develop Kerr induced self-focusing or self-defocusing, depending upon the waveguide structure and composition. Optical nonlinearity in chalcogenide waveguide is studied in the 1200 nm to 1550 nm wavelength range in femtosecond regime. Results of the proposed technique compare favorably with n2 values obtained with the Z-scan technique. In addition, beam self-trapping in the chalcogenide waveguides due to material photosensitivity is also observed.

Laser Desorption Ionization Time-of-Flight Mass Spectrometry was exploited for the characterization of Ge-As-Se chalcogenide glasses and corresponding thin films fabricated using pulsed laser deposition. Main achievement of the paper is the determination of laser generated clusters' stoichiometry. The clusters observed were As-b(+) (b = 1-3), Se-2(-), binary AsbSe+ (b = 1-3), AsbSec- (b = 1-3, c = 1-4), Ge2Sec- (c = 2-3), As3Se2+, Ge2Asb- (b = 2-3), Ge3Asb- (b = 1-2), Ge3Se4-, As5Sec- (c = 4-5), GeAsSe4-, GeaAsSe5- (a = 1-4), GeAs2Se3-, GeAs3Se2-, Ge2As2Se2-, Ge2AsSec- (c = 6-7), and GeAs3Sec- (c = 5-6) (in positive as well as in negative ion mode). The stoichiometries of identified species are compared with the structural units of the glasses/thin films revealed via Raman scattering spectra analysis. Some species are suggested to be fragments of bulk glass as well as thin films. Described method is useful also for the evaluation of the contamination of chalcogenide glasses or their thin films.

This paper presents the development of an integrated chalcogenide glass platform to realize an evanescent wave sensor in the mid-infrared spectral range. The proposed structure is that of a ribbon waveguide on a silicon substrate, whose core and confinement layers are respectively made of Ge 12.5 Sb 25 Se 62.5 and Ge 28.1 Sb 6.3 Se 65.6. We will first detail the simulation results allowing to optimize the structure in order to obtain on the one hand, the monomodal transmission at the wavelengths 6.3 µm and 7.8 µm and on the other hand, a high rate of overlapping of the evanescent wave with the superstrate in order to detect molecules absorbing specifically at these two wavelengths. Finally, optical loss measurements on these guides at λ=1.55 µm as well as light propagation at λ=7.8 µm will be presented.

The development of optical sensors operating in the mid-infrared is a major challenge to detect (bio-) molecules. Indeed, the mid-infrared (4000 - 400 cm-1) contains a large majority of the absorptions due to the vibrations of organic molecules. The objective of this research is to develop more selective, more sensitive and more compact sensors. The research work presented in this manuscript concerns the development of chalcogenide glass-based optical waveguides sensitive to target molecules via the absorption of the evanescent part of the guided light propagating on the surface of the guide. The synthesis of infrared materials is one of the key steps. Chalcogenide glasses are particularly suitable materials for this application of pollutant detection. These glasses have a wide range of transparency in the infrared (2 - 15 µm for selenium-based glasses) and high refractive indices (between 2 and 3). The development of the waveguide requires the fabrication of thin layers of chalcogenide glass by RF magnetron sputtering. In order to control the development of the infrared microsensor, a design of experiments has been developed to study the influence of the deposition parameters on the characteristics of the thin films. The architecture of the guide has been defined and realized by RIE-ICP (reactive ion etching coupled to the inductively coupled plasma etching process) and the optical loss and injection measurements in the MIR (6.3 µm and 7.8 µm) have been performed. These are the very first guides operating so far in the mid-infrared. The last step consists in functionalizing the surface of the guide to increase its selectivity. First tests have been performed on a ZnSe ATR crystal with a hydrophobic polymer. They allowed the detection of polluting molecules absorbing at 13.8 µm, present in very low concentration (25 ppb) in hydrocarbon solutions (BTX) or more complex waters (sewage plant waters and groundwater).

The development of optical sensors operating in the mid-infrared is a major challenge to detect (bio-) molecules. Indeed, the mid-infrared (4000 - 400 cm-1) contains a large majority of the absorptions due to the vibrations of organic molecules. The objective of this research is to develop more selective, more sensitive and more compact sensors. The research work presented in this manuscript concerns the development of chalcogenide glass-based optical waveguides sensitive to target molecules via the absorption of the evanescent part of the guided light propagating on the surface of the guide. The synthesis of infrared materials is one of the key steps. Chalcogenide glasses are particularly suitable materials for this application of pollutant detection. These glasses have a wide range of transparency in the infrared (2 - 15 µm for selenium-based glasses) and high refractive indices (between 2 and 3). The development of the waveguide requires the fabrication of thin layers of chalcogenide glass by RF magnetron sputtering. In order to control the development of the infrared microsensor, a design of experiments has been developed to study the influence of the deposition parameters on the characteristics of the thin films. The architecture of the guide has been defined and realized by RIE-ICP (reactive ion etching coupled to the inductively coupled plasma etching process) and the optical loss and injection measurements in the MIR (6.3 µm and 7.8 µm) have been performed. These are the very first guides operating so far in the mid-infrared. The final step is to functionalize the surface of the guide to increase its selectivity. First tests have been performed on a ZnSe ATR crystal with a hydrophobic polymer. They allowed the detection of polluting molecules absorbing at 13.8 µm, present in very low concentration (25 ppb) in hydrocarbon solutions (BTX) or more complex waters (sewage plant waters and groundwater).

Chalcogenide glasses from (GeSe2)​100-​x(Sb2Se3)​x system were synthesized, with x varying from 5 to 70, in order to evaluate the influence of antimony selenide addn. on nonlinear optical properties and photosensitivity. Nonlinear refractive index and two photon absorption coeffs. were measured both at 1064 nm in picosecond regime using the Z-​scan technique and at 1.55 μm in femtosecond regime using an original method based on direct anal. of beam profile change while propagating in the chalcogenide glasses. The study of their photosensitivity at 1.55 μm revealed highly glass compn. dependent behavior and quasi-​photostable compns. have been identified in femtosecond regime. To better understand these characteristics, the evolution of the glass transition temp., d. and structure with the chem. compn. were detd.

The 3-15 μm range is a key region for a large number of applications in diverse areas such as biology and medicine, molecular spectroscopy, ground based and space borne environmental monitoring but also an important issue of instrumentation for astronomy and astrophysics to achieve complex but very reliable instruments. Going to the mid IR region is crucial for the observation of warm objects around 300 K and the characterization of their spectral features, considered as signatures for biological activity (e.g. water, ozone, carbon dioxide). Most infrared signatures or "fingerprints" (fundamental transitions) of organic species and biomolecules are essentially located in this spectral window. Thus, infrared spectroscopy is a powerful tool for detecting and determining the composition of complex samples.

Chalcogenide glasses from Ge-Sb-Se ternary system with different antimony content were fabricated and basic physico-chemical properties (chemical composition, thermal characteristics, density) were evaluated considering the glassy network connectivity. Optical properties of the glasses were heavily studied employing transmission spectroscopy, prism coupling technique, and particularly spectroscopic ellipsometry covering broad spectral range (0.3-20 μm). Refractive indices data show very good agreement between ellipsometry and prism coupling techniques in near-infrared range. Moreover, the reliability of infrared spectroscopic ellipsometry was demonstrated for precise determination of refractive index of chalcogenide glasses in near- as well as middle-infrared spectral regions.

The primary objective of this study is the development of transparent thin film materials in the IR enabling strong infrared absorption of organic compounds in the vicinity of metal nanoparticles by the surface plasmon effect. For developing these optical micro-sensors, hetero-structures combining gold nanoparticles and chalcogenide planar waveguides are fabricated and adequately characterized. Single As2S3 and Ge25Sb10Se65 amorphous chalcogenide thin films are prepared by radio-frequency magnetron sputtering. For the fabrication of gold nanoparticles on a chalcogenide planar waveguide, direct current sputtering is employed. Fabricated single layers or hetero-structures are characterized using various techniques to investigate the influence of deposition parameters. The nanoparticles of gold are functionalized by a self-assembled monolayer of 4-nitrothiophenol. Finally, the surface enhanced infrared absorption spectra of 4-nitrothiophenol self-assembled on fabricated Au/Ge-Sb-Se thin films hetero-structures are measured and analyzed. This optical component presents a ~24 enhancement factor for the detection of NO2 symmetric stretching vibration band of 4-nitrothiophenol at 1336 cm−1.