Radwan Chahal - Academia.edu (original) (raw)

Papers by Radwan Chahal

Research paper thumbnail of The structure of near stoichiometric Ge-Ga-Sb-S glasses: A reverse Monte Carlo study

Journal of Non-crystalline Solids, Feb 1, 2019

The structure of Ge 22 Ga 3 Sb 10 S 65 and Ge 15 Ga 10 Sb 10 S 65 glasses was investigated by neu... more The structure of Ge 22 Ga 3 Sb 10 S 65 and Ge 15 Ga 10 Sb 10 S 65 glasses was investigated by neutron diffraction (ND), X-ray diffraction (XRD), and extended X-ray absorption fine structure (EXAFS) measurements at the Ge, Ga and Sb K-edges. Experimental data sets were fitted simultaneously in the framework of the reverse Monte Carlo (RMC) simulation technique. Short range order parameters were determined from the obtained large-scale configurations. It was found that the coordination numbers of Ge, Sb and S are around the values predicted by the Mott-rule (4, 3 and 2, respectively). The Ga atoms have on average 4 nearest neighbors. The structure of these stoichiometric glasses can be described by the chemically ordered network model: Ge-S, GaS and Sb-S bonds are the most important. Long Sb-S distances (0.3-0.4 Å higher than the usual covalent bond lengths) are observed, suggesting that Sb atoms can be found in various local environments.

Research paper thumbnail of Chemical order in Ge-Ga-Sb-Se glasses

Journal of Non-crystalline Solids, Mar 1, 2018

The short range order in Ge 30 Ga 5 Sb 10 Se 55 and Ge 21 Ga 5 Sb 10 Se 64 glasses was investigat... more The short range order in Ge 30 Ga 5 Sb 10 Se 55 and Ge 21 Ga 5 Sb 10 Se 64 glasses was investigated by X-ray (XRD) and neutron diffraction (ND) as well as extended X-ray absorption fine structure (EXAFS) measurements at the Ge, Ga, Sb and Se K-edges. Large scale structural models were obtained by fitting simultaneously the experimental data sets by reverse Monte Carlo (RMC) simulation technique. It was found that Ge, Sb and Se atoms follow the Mott-rule and have 4, 3 and 2 nearest neighbors, respectively. The average coordination number of the Ga atoms was around 4. The structure of these glasses can be described by the chemically ordered network model: the Ge-Se, Ga-Se and Sb-Se bonds are the most prominent while Ge-Ge and Ge-Sb bonds are formed only in Se-poor compositions. Models generated by RMC contained some long distances (0.3-0.4 Å higher than the usual covalent bond lengths) between Ge-Se and/or Ge-Ge pairs. Dedicated simulation runs confirm the existence of these bonds.

Research paper thumbnail of Développement d'une source optique intégrée émettant dans le moyen infra-rouge à partir de verres de chalcogénure dopés par des ions de terres rares

HAL (Le Centre pour la Communication Scientifique Directe), Jul 3, 2017

Cet article presente des resultats de photoluminescence (PL) guidee dans le moyen-infrarouge (2-5... more Cet article presente des resultats de photoluminescence (PL) guidee dans le moyen-infrarouge (2-5 µm) obtenus a partir de guides d’onde integres en verres de chalcogenure dopes par des ions Pr 3+ . La fabrication de verres de chalcogenures, leur depot par pulverisation cathodique radiofrequence magnetron ainsi que leur mise en forme de guides d’onde ruban par photolithographie et gravure seche sont egalement decrits. Des spectres de PL guidee large bande dans le moyen-infrarouge sont enregistres pour la premiere fois pour des longueurs d’onde superieures a 4 µm pour des guides incorporant des ions de terre rare.

Research paper thumbnail of Réalisation de structures optiques verticales en verres de chalcogénure pour des applications dans le proche et moyen infrarouge

HAL (Le Centre pour la Communication Scientifique Directe), Jul 11, 2013

Research paper thumbnail of Design of mid-IR microstructured fiber light source based on dysprosium doped chalcogenide glass

The paper deals with the design of a medium infrared (Mid-IR) light source based on a microstruct... more The paper deals with the design of a medium infrared (Mid-IR) light source based on a microstructured fiber made of dysprosium doped chalcogenide glass, Dy3+:Ga5Ge20Sb10S65. It is constituted by the cascade of a laser cavity and an optical amplifier which could be fabricated in the same microstructured fiber. In order to obtain realistic results, the simulation is performed by taking into account the spectroscopic parameters directly measured on preliminary samples of Dy3+:Ga5Ge20Sb10S65 glasses. The main objective is to investigate the feasibility of optical beam emission close to 4.4 μm wavelength. An output power of 547.3 mW with an input pump power of 3 W is calculated for an optical fiber about 1.5 m long and with a dopant concentration close to 6 × 1025 ions/m3. This result indicates that the designed source configuration is feasible for medium infrared light generation and it could find application in optical free propagation link, optical remote sensing and biomedicine.

Research paper thumbnail of Short range order in Ge-Ga-Se glasses

Journal of Alloys and Compounds, Dec 1, 2015

Short range order of glassy Ge 20 Ga 10 Se 70 and Ge 20 Ga 5 Se 75 was investigated by neutron di... more Short range order of glassy Ge 20 Ga 10 Se 70 and Ge 20 Ga 5 Se 75 was investigated by neutron diffraction and extended X-ray absorption fine structure spectroscopy (EXAFS) at Ge, Ga and Se K-edges. For each composition large scale structural models were obtained by fitting simultaneously the four experimental datasets in the framework of the reverse Monte Carlo simulation technique. It was found that both Ge and Ga are predominantly fourfold coordinated. The quality of the fits was strongly improved by introducing Ge-Ga bonding. Models giving the best agreement with experimental data show that Ga has a complex effect on the Ge-Se host matrix: i) it enters the covalent network by forming GaGe bonds ii) by decreasing the number of Se atoms around Ge, it contributes to the formation of Se-Se bonds, which may explain the higher solubility of lanthanide ions iii) the average coordination number of Se increases due to the Ga-Se 'extra' bonds. The higher average coordination of the network may be responsible for the increase of T g upon adding Ga to Ge-Se glasses.

Research paper thumbnail of Ultrafast fiber-based lasers beyond 2 µm

Research paper thumbnail of Rare-earth doped chalcogenide fibers for all-optical gas sensing in the midinfrared spectral range

HAL (Le Centre pour la Communication Scientifique Directe), Jun 21, 2015

International audienc

Research paper thumbnail of Fabrication of high optical quality Ge-As-Se glasses for the development of low-loss microstructured optical fibers

In the last twenty years the field of chalcogenide glasses has seen increasing interest, due to t... more In the last twenty years the field of chalcogenide glasses has seen increasing interest, due to their broad transparency window in the mid-IR. Furthermore, chalcogenides are showing one of the highest nonlinear refractive indices among glasses. Due to these reasons, the development of chalcogenide microstructured optical fibers with low optical losses can allow for new breakthroughs in various research fields, e.g. new mid-IR laser sources, mid-IR spectroscopy, sensing and applications based on nonlinear effects, like supercontinuum generation. In this framework, chalcogenide glasses with the lowest possible amount of impurities are needed to minimize absorption losses. This study is focused on the attempt of eliminating the pollutants usually giving rise to absorption peaks inside the transparency windows: oxygen, hydrogen, carbon and water. Samples were prepared using a double distillation method: getters that can react with the impurities during the synthesis were added to the initial charge, and the reaction byproducts were eliminated by a two-steps distillation process. Ge 10 As 22 Se 68 was chosen as the system to study because of its nonlinear, optical and thermomechanical properties. Different combinations of chlorides (for the elimination of hydrogen and carbon) and metals (for the elimination of oxygen) were used, and the attenuation spectra of the resulting glasses were compared. The chosen chlorides are TeCl 4 , SeCl 4 , SbCl 3 , GaCl 3 ; the metals are Mg, Al, Zr, Ni. A holey fiber has been realized by casting method using the best sample, showing that the method is suitable for this composition and that the attenuation before and after the casting are comparable.

Research paper thumbnail of 2-10 µm Mid-infrared supercontinuum generation in cascaded optical fibers: Experiment and modelling

HAL (Le Centre pour la Communication Scientifique Directe), Mar 6, 2021

International audienceSupercontinuum (SC) generation towards the mid-infrared (MIR) range is an a... more International audienceSupercontinuum (SC) generation towards the mid-infrared (MIR) range is an active field of research and development motivated by a wide range of applications including optical coherence tomography (OCT), material processing, optical sensing and absorption spectroscopy. In this work, we investigate mid-IR SC generation in a cascaded silica and soft-glass fiber system directly pumped with a commercially-available picosecond fiber laser operating in the telecommunications window at 1.55 μm. This all-fiber system is shown to generate a flat broadband mid-IR-SC covering the entire range from 2 to 10 μm with several tens of mW of output power. This technique paves the way for practical and robust broadband SC sources in the mid-IR without the requirement of mid-infrared pump sources or Thulium-doped fiber amplifiers. We also describe a fully-realistic numerical model used to simulate the nonlinear pulse propagation through the cascaded fiber system and use our numerical results to discuss the physical processes underlying the spectral broadening in the cascaded system

Research paper thumbnail of Optiques intégrées à base de verres de chalcogénure pour des applications dans le proche et le moyen infra-rouge

HAL (Le Centre pour la Communication Scientifique Directe), Jul 3, 2017

Cet article presente l’ensemble des resultats experimentaux de caracterisations optiques dans le ... more Cet article presente l’ensemble des resultats experimentaux de caracterisations optiques dans le proche et le moyen infrarouge d’une plateforme integree en verres de chalcogenure en exploitant leur propriete non lineaire d’ordre 3 et leur large transparence dans l’infrarouge. Ainsi, des mesures notamment de melange a quatre ondes ont ete realisees sur des guides de type ruban et des microcavites en anneau a 1550 nm. Enfin, des mesures de transduction ont permis de detecter des substances liquides absorbantes dans le moyen infrarouge.

Research paper thumbnail of Doped chalcogenide glasses for luminescence and laser application

Research paper thumbnail of Local motifs in GeS2–Ga2S3 glasses

Journal of Alloys and Compounds, Jul 1, 2016

The structure of (GeS 2) 0.75 (Ga 2 S 3) 0.25 and (GeS 2) 0.83 (Ga 2 S 3) 0.17 glasses was invest... more The structure of (GeS 2) 0.75 (Ga 2 S 3) 0.25 and (GeS 2) 0.83 (Ga 2 S 3) 0.17 glasses was investigated by Raman scattering, high energy X-ray diffraction and extended X-ray fine structure (EXAFS) measurements at the Ga and Ge K-edges. The reverse Monte Carlo simulation technique (RMC) was used to obtain structural models compatible with diffraction and EXAFS datasets. It was found that the coordination number of Ga is close to four. While Ge atoms have only S neighbors, Ga binds to S as well as to Ga atoms showing a violation of chemical ordering in GeS 2-Ga 2 S 3 glasses. Analysis of the corner-and edge-sharing between [GeS 4/2 ] units revealed that about 30% of germanium atoms participate in the edge-shared tetrahedra.

Research paper thumbnail of Fabrication of chalcogenide microstructured optical preforms and fibers by additive manufacturing of chalcogenide glasses

Optical Components and Materials XX, Mar 14, 2023

Research paper thumbnail of Fabrication of high optical quality Ge-As-Se glasses for the development of low-loss microstructured optical fibers

Optical Components and Materials XVI

In the last twenty years the field of chalcogenide glasses has seen increasing interest, due to t... more In the last twenty years the field of chalcogenide glasses has seen increasing interest, due to their broad transparency window in the mid-IR. Furthermore, chalcogenides are showing one of the highest nonlinear refractive indices among glasses. Due to these reasons, the development of chalcogenide microstructured optical fibers with low optical losses can allow for new breakthroughs in various research fields, e.g. new mid-IR laser sources, mid-IR spectroscopy, sensing and applications based on nonlinear effects, like supercontinuum generation. In this framework, chalcogenide glasses with the lowest possible amount of impurities are needed to minimize absorption losses. This study is focused on the attempt of eliminating the pollutants usually giving rise to absorption peaks inside the transparency windows: oxygen, hydrogen, carbon and water. Samples were prepared using a double distillation method: getters that can react with the impurities during the synthesis were added to the initial charge, and the reaction byproducts were eliminated by a two-steps distillation process. Ge 10 As 22 Se 68 was chosen as the system to study because of its nonlinear, optical and thermomechanical properties. Different combinations of chlorides (for the elimination of hydrogen and carbon) and metals (for the elimination of oxygen) were used, and the attenuation spectra of the resulting glasses were compared. The chosen chlorides are TeCl 4 , SeCl 4 , SbCl 3 , GaCl 3 ; the metals are Mg, Al, Zr, Ni. A holey fiber has been realized by casting method using the best sample, showing that the method is suitable for this composition and that the attenuation before and after the casting are comparable.

Research paper thumbnail of Rare-earth doped chalcogenide fibers for all-optical gas sensing in the midinfrared spectral range

Research paper thumbnail of Investigation on Chalcogenide Glass Additive Manufacturing for Shaping Mid-infrared Optical Components and Microstructured Optical Fibers

Crystals

In this work, an original way of shaping chalcogenide optical components has been investigated. T... more In this work, an original way of shaping chalcogenide optical components has been investigated. Thorough evaluation of the properties of chalcogenide glasses before and after 3D printing has been carried out in order to determine the impact of the 3D additive manufacturing process on the material. In order to evaluate the potential of such additive glass manufacturing, several preliminary results obtained with various chalcogenide objects and components, such as cylinders, beads, drawing preforms and sensors, are described and discussed. This innovative 3D printing method opens the way for many applications involving chalcogenide fiber elaboration, but also many other chalcogenide glass optical devices.

Research paper thumbnail of Ultrafast fiber-based lasers beyond 2 µm

Laser Congress 2017 (ASSL, LAC), 2017

Research paper thumbnail of Optiques intégrées à base de verres de chalcogénure pour des applications dans le proche et le moyen infra-rouge

Cet article presente l’ensemble des resultats experimentaux de caracterisations optiques dans le ... more Cet article presente l’ensemble des resultats experimentaux de caracterisations optiques dans le proche et le moyen infrarouge d’une plateforme integree en verres de chalcogenure en exploitant leur propriete non lineaire d’ordre 3 et leur large transparence dans l’infrarouge. Ainsi, des mesures notamment de melange a quatre ondes ont ete realisees sur des guides de type ruban et des microcavites en anneau a 1550 nm. Enfin, des mesures de transduction ont permis de detecter des substances liquides absorbantes dans le moyen infrarouge.

Research paper thumbnail of Cascaded mid-IR supercontinuum generation in chalcogenide microstructured optical fibers from 2 to 10 μm

Compared to oxide based glasses, vitreous materials composed of chalcogen elements (S, Se, Te) sh... more Compared to oxide based glasses, vitreous materials composed of chalcogen elements (S, Se, Te) show large transparency windows in the infrared. Indeed, chalcogenide fibers can be transparent from the visible up to 12-15 μm, depending on their compositions. The IR signatures of most molecules, including biomolecules, are located in this spectral domain, which allows in situ, non-invasive and real-time detection of gaz or organics molecules. Indeed, chalcogenide glasses can present a high non-linear coefficient (n2), 100 to 1000 times larger than for silica glass, depending on the composition. An original way to obtain fibers is to design microstructured optical fibers (MOFs). These fibers present unique optical properties thanks to the high degree of freedom in the design of their geometrical structure. Various chalcogenide MOFs operating in the mid-IR range have been elaborated in order to associate the high nonlinear properties of these glasses and the original MOF properties. Diff...

Research paper thumbnail of The structure of near stoichiometric Ge-Ga-Sb-S glasses: A reverse Monte Carlo study

Journal of Non-crystalline Solids, Feb 1, 2019

The structure of Ge 22 Ga 3 Sb 10 S 65 and Ge 15 Ga 10 Sb 10 S 65 glasses was investigated by neu... more The structure of Ge 22 Ga 3 Sb 10 S 65 and Ge 15 Ga 10 Sb 10 S 65 glasses was investigated by neutron diffraction (ND), X-ray diffraction (XRD), and extended X-ray absorption fine structure (EXAFS) measurements at the Ge, Ga and Sb K-edges. Experimental data sets were fitted simultaneously in the framework of the reverse Monte Carlo (RMC) simulation technique. Short range order parameters were determined from the obtained large-scale configurations. It was found that the coordination numbers of Ge, Sb and S are around the values predicted by the Mott-rule (4, 3 and 2, respectively). The Ga atoms have on average 4 nearest neighbors. The structure of these stoichiometric glasses can be described by the chemically ordered network model: Ge-S, GaS and Sb-S bonds are the most important. Long Sb-S distances (0.3-0.4 Å higher than the usual covalent bond lengths) are observed, suggesting that Sb atoms can be found in various local environments.

Research paper thumbnail of Chemical order in Ge-Ga-Sb-Se glasses

Journal of Non-crystalline Solids, Mar 1, 2018

The short range order in Ge 30 Ga 5 Sb 10 Se 55 and Ge 21 Ga 5 Sb 10 Se 64 glasses was investigat... more The short range order in Ge 30 Ga 5 Sb 10 Se 55 and Ge 21 Ga 5 Sb 10 Se 64 glasses was investigated by X-ray (XRD) and neutron diffraction (ND) as well as extended X-ray absorption fine structure (EXAFS) measurements at the Ge, Ga, Sb and Se K-edges. Large scale structural models were obtained by fitting simultaneously the experimental data sets by reverse Monte Carlo (RMC) simulation technique. It was found that Ge, Sb and Se atoms follow the Mott-rule and have 4, 3 and 2 nearest neighbors, respectively. The average coordination number of the Ga atoms was around 4. The structure of these glasses can be described by the chemically ordered network model: the Ge-Se, Ga-Se and Sb-Se bonds are the most prominent while Ge-Ge and Ge-Sb bonds are formed only in Se-poor compositions. Models generated by RMC contained some long distances (0.3-0.4 Å higher than the usual covalent bond lengths) between Ge-Se and/or Ge-Ge pairs. Dedicated simulation runs confirm the existence of these bonds.

Research paper thumbnail of Développement d'une source optique intégrée émettant dans le moyen infra-rouge à partir de verres de chalcogénure dopés par des ions de terres rares

HAL (Le Centre pour la Communication Scientifique Directe), Jul 3, 2017

Cet article presente des resultats de photoluminescence (PL) guidee dans le moyen-infrarouge (2-5... more Cet article presente des resultats de photoluminescence (PL) guidee dans le moyen-infrarouge (2-5 µm) obtenus a partir de guides d’onde integres en verres de chalcogenure dopes par des ions Pr 3+ . La fabrication de verres de chalcogenures, leur depot par pulverisation cathodique radiofrequence magnetron ainsi que leur mise en forme de guides d’onde ruban par photolithographie et gravure seche sont egalement decrits. Des spectres de PL guidee large bande dans le moyen-infrarouge sont enregistres pour la premiere fois pour des longueurs d’onde superieures a 4 µm pour des guides incorporant des ions de terre rare.

Research paper thumbnail of Réalisation de structures optiques verticales en verres de chalcogénure pour des applications dans le proche et moyen infrarouge

HAL (Le Centre pour la Communication Scientifique Directe), Jul 11, 2013

Research paper thumbnail of Design of mid-IR microstructured fiber light source based on dysprosium doped chalcogenide glass

The paper deals with the design of a medium infrared (Mid-IR) light source based on a microstruct... more The paper deals with the design of a medium infrared (Mid-IR) light source based on a microstructured fiber made of dysprosium doped chalcogenide glass, Dy3+:Ga5Ge20Sb10S65. It is constituted by the cascade of a laser cavity and an optical amplifier which could be fabricated in the same microstructured fiber. In order to obtain realistic results, the simulation is performed by taking into account the spectroscopic parameters directly measured on preliminary samples of Dy3+:Ga5Ge20Sb10S65 glasses. The main objective is to investigate the feasibility of optical beam emission close to 4.4 μm wavelength. An output power of 547.3 mW with an input pump power of 3 W is calculated for an optical fiber about 1.5 m long and with a dopant concentration close to 6 × 1025 ions/m3. This result indicates that the designed source configuration is feasible for medium infrared light generation and it could find application in optical free propagation link, optical remote sensing and biomedicine.

Research paper thumbnail of Short range order in Ge-Ga-Se glasses

Journal of Alloys and Compounds, Dec 1, 2015

Short range order of glassy Ge 20 Ga 10 Se 70 and Ge 20 Ga 5 Se 75 was investigated by neutron di... more Short range order of glassy Ge 20 Ga 10 Se 70 and Ge 20 Ga 5 Se 75 was investigated by neutron diffraction and extended X-ray absorption fine structure spectroscopy (EXAFS) at Ge, Ga and Se K-edges. For each composition large scale structural models were obtained by fitting simultaneously the four experimental datasets in the framework of the reverse Monte Carlo simulation technique. It was found that both Ge and Ga are predominantly fourfold coordinated. The quality of the fits was strongly improved by introducing Ge-Ga bonding. Models giving the best agreement with experimental data show that Ga has a complex effect on the Ge-Se host matrix: i) it enters the covalent network by forming GaGe bonds ii) by decreasing the number of Se atoms around Ge, it contributes to the formation of Se-Se bonds, which may explain the higher solubility of lanthanide ions iii) the average coordination number of Se increases due to the Ga-Se 'extra' bonds. The higher average coordination of the network may be responsible for the increase of T g upon adding Ga to Ge-Se glasses.

Research paper thumbnail of Ultrafast fiber-based lasers beyond 2 µm

Research paper thumbnail of Rare-earth doped chalcogenide fibers for all-optical gas sensing in the midinfrared spectral range

HAL (Le Centre pour la Communication Scientifique Directe), Jun 21, 2015

International audienc

Research paper thumbnail of Fabrication of high optical quality Ge-As-Se glasses for the development of low-loss microstructured optical fibers

In the last twenty years the field of chalcogenide glasses has seen increasing interest, due to t... more In the last twenty years the field of chalcogenide glasses has seen increasing interest, due to their broad transparency window in the mid-IR. Furthermore, chalcogenides are showing one of the highest nonlinear refractive indices among glasses. Due to these reasons, the development of chalcogenide microstructured optical fibers with low optical losses can allow for new breakthroughs in various research fields, e.g. new mid-IR laser sources, mid-IR spectroscopy, sensing and applications based on nonlinear effects, like supercontinuum generation. In this framework, chalcogenide glasses with the lowest possible amount of impurities are needed to minimize absorption losses. This study is focused on the attempt of eliminating the pollutants usually giving rise to absorption peaks inside the transparency windows: oxygen, hydrogen, carbon and water. Samples were prepared using a double distillation method: getters that can react with the impurities during the synthesis were added to the initial charge, and the reaction byproducts were eliminated by a two-steps distillation process. Ge 10 As 22 Se 68 was chosen as the system to study because of its nonlinear, optical and thermomechanical properties. Different combinations of chlorides (for the elimination of hydrogen and carbon) and metals (for the elimination of oxygen) were used, and the attenuation spectra of the resulting glasses were compared. The chosen chlorides are TeCl 4 , SeCl 4 , SbCl 3 , GaCl 3 ; the metals are Mg, Al, Zr, Ni. A holey fiber has been realized by casting method using the best sample, showing that the method is suitable for this composition and that the attenuation before and after the casting are comparable.

Research paper thumbnail of 2-10 µm Mid-infrared supercontinuum generation in cascaded optical fibers: Experiment and modelling

HAL (Le Centre pour la Communication Scientifique Directe), Mar 6, 2021

International audienceSupercontinuum (SC) generation towards the mid-infrared (MIR) range is an a... more International audienceSupercontinuum (SC) generation towards the mid-infrared (MIR) range is an active field of research and development motivated by a wide range of applications including optical coherence tomography (OCT), material processing, optical sensing and absorption spectroscopy. In this work, we investigate mid-IR SC generation in a cascaded silica and soft-glass fiber system directly pumped with a commercially-available picosecond fiber laser operating in the telecommunications window at 1.55 μm. This all-fiber system is shown to generate a flat broadband mid-IR-SC covering the entire range from 2 to 10 μm with several tens of mW of output power. This technique paves the way for practical and robust broadband SC sources in the mid-IR without the requirement of mid-infrared pump sources or Thulium-doped fiber amplifiers. We also describe a fully-realistic numerical model used to simulate the nonlinear pulse propagation through the cascaded fiber system and use our numerical results to discuss the physical processes underlying the spectral broadening in the cascaded system

Research paper thumbnail of Optiques intégrées à base de verres de chalcogénure pour des applications dans le proche et le moyen infra-rouge

HAL (Le Centre pour la Communication Scientifique Directe), Jul 3, 2017

Cet article presente l’ensemble des resultats experimentaux de caracterisations optiques dans le ... more Cet article presente l’ensemble des resultats experimentaux de caracterisations optiques dans le proche et le moyen infrarouge d’une plateforme integree en verres de chalcogenure en exploitant leur propriete non lineaire d’ordre 3 et leur large transparence dans l’infrarouge. Ainsi, des mesures notamment de melange a quatre ondes ont ete realisees sur des guides de type ruban et des microcavites en anneau a 1550 nm. Enfin, des mesures de transduction ont permis de detecter des substances liquides absorbantes dans le moyen infrarouge.

Research paper thumbnail of Doped chalcogenide glasses for luminescence and laser application

Research paper thumbnail of Local motifs in GeS2–Ga2S3 glasses

Journal of Alloys and Compounds, Jul 1, 2016

The structure of (GeS 2) 0.75 (Ga 2 S 3) 0.25 and (GeS 2) 0.83 (Ga 2 S 3) 0.17 glasses was invest... more The structure of (GeS 2) 0.75 (Ga 2 S 3) 0.25 and (GeS 2) 0.83 (Ga 2 S 3) 0.17 glasses was investigated by Raman scattering, high energy X-ray diffraction and extended X-ray fine structure (EXAFS) measurements at the Ga and Ge K-edges. The reverse Monte Carlo simulation technique (RMC) was used to obtain structural models compatible with diffraction and EXAFS datasets. It was found that the coordination number of Ga is close to four. While Ge atoms have only S neighbors, Ga binds to S as well as to Ga atoms showing a violation of chemical ordering in GeS 2-Ga 2 S 3 glasses. Analysis of the corner-and edge-sharing between [GeS 4/2 ] units revealed that about 30% of germanium atoms participate in the edge-shared tetrahedra.

Research paper thumbnail of Fabrication of chalcogenide microstructured optical preforms and fibers by additive manufacturing of chalcogenide glasses

Optical Components and Materials XX, Mar 14, 2023

Research paper thumbnail of Fabrication of high optical quality Ge-As-Se glasses for the development of low-loss microstructured optical fibers

Optical Components and Materials XVI

In the last twenty years the field of chalcogenide glasses has seen increasing interest, due to t... more In the last twenty years the field of chalcogenide glasses has seen increasing interest, due to their broad transparency window in the mid-IR. Furthermore, chalcogenides are showing one of the highest nonlinear refractive indices among glasses. Due to these reasons, the development of chalcogenide microstructured optical fibers with low optical losses can allow for new breakthroughs in various research fields, e.g. new mid-IR laser sources, mid-IR spectroscopy, sensing and applications based on nonlinear effects, like supercontinuum generation. In this framework, chalcogenide glasses with the lowest possible amount of impurities are needed to minimize absorption losses. This study is focused on the attempt of eliminating the pollutants usually giving rise to absorption peaks inside the transparency windows: oxygen, hydrogen, carbon and water. Samples were prepared using a double distillation method: getters that can react with the impurities during the synthesis were added to the initial charge, and the reaction byproducts were eliminated by a two-steps distillation process. Ge 10 As 22 Se 68 was chosen as the system to study because of its nonlinear, optical and thermomechanical properties. Different combinations of chlorides (for the elimination of hydrogen and carbon) and metals (for the elimination of oxygen) were used, and the attenuation spectra of the resulting glasses were compared. The chosen chlorides are TeCl 4 , SeCl 4 , SbCl 3 , GaCl 3 ; the metals are Mg, Al, Zr, Ni. A holey fiber has been realized by casting method using the best sample, showing that the method is suitable for this composition and that the attenuation before and after the casting are comparable.

Research paper thumbnail of Rare-earth doped chalcogenide fibers for all-optical gas sensing in the midinfrared spectral range

Research paper thumbnail of Investigation on Chalcogenide Glass Additive Manufacturing for Shaping Mid-infrared Optical Components and Microstructured Optical Fibers

Crystals

In this work, an original way of shaping chalcogenide optical components has been investigated. T... more In this work, an original way of shaping chalcogenide optical components has been investigated. Thorough evaluation of the properties of chalcogenide glasses before and after 3D printing has been carried out in order to determine the impact of the 3D additive manufacturing process on the material. In order to evaluate the potential of such additive glass manufacturing, several preliminary results obtained with various chalcogenide objects and components, such as cylinders, beads, drawing preforms and sensors, are described and discussed. This innovative 3D printing method opens the way for many applications involving chalcogenide fiber elaboration, but also many other chalcogenide glass optical devices.

Research paper thumbnail of Ultrafast fiber-based lasers beyond 2 µm

Laser Congress 2017 (ASSL, LAC), 2017

Research paper thumbnail of Optiques intégrées à base de verres de chalcogénure pour des applications dans le proche et le moyen infra-rouge

Cet article presente l’ensemble des resultats experimentaux de caracterisations optiques dans le ... more Cet article presente l’ensemble des resultats experimentaux de caracterisations optiques dans le proche et le moyen infrarouge d’une plateforme integree en verres de chalcogenure en exploitant leur propriete non lineaire d’ordre 3 et leur large transparence dans l’infrarouge. Ainsi, des mesures notamment de melange a quatre ondes ont ete realisees sur des guides de type ruban et des microcavites en anneau a 1550 nm. Enfin, des mesures de transduction ont permis de detecter des substances liquides absorbantes dans le moyen infrarouge.

Research paper thumbnail of Cascaded mid-IR supercontinuum generation in chalcogenide microstructured optical fibers from 2 to 10 μm

Compared to oxide based glasses, vitreous materials composed of chalcogen elements (S, Se, Te) sh... more Compared to oxide based glasses, vitreous materials composed of chalcogen elements (S, Se, Te) show large transparency windows in the infrared. Indeed, chalcogenide fibers can be transparent from the visible up to 12-15 μm, depending on their compositions. The IR signatures of most molecules, including biomolecules, are located in this spectral domain, which allows in situ, non-invasive and real-time detection of gaz or organics molecules. Indeed, chalcogenide glasses can present a high non-linear coefficient (n2), 100 to 1000 times larger than for silica glass, depending on the composition. An original way to obtain fibers is to design microstructured optical fibers (MOFs). These fibers present unique optical properties thanks to the high degree of freedom in the design of their geometrical structure. Various chalcogenide MOFs operating in the mid-IR range have been elaborated in order to associate the high nonlinear properties of these glasses and the original MOF properties. Diff...