51 research outputs found
S-Tapered Fluoride Optical Fiber for Refractive Index Sensing in the Mid-Infrared
No full textThis paper illustrates the first S-tapered optical fiber obtained by employing fluoride glass, via off-axis pulling and filament heating. The S-tapered optical fiber has been designed via three-dimensional beam propagation method and its performance with respect to the surrounding refractive index has been numerically predicted. The fabrication has been conducted using a commercial glass processor, operating at low power due to the glass thermal properties. The S-tapered optical fiber transmission spectrum has been measured in the mid-infrared when immersed in different surrounding liquids, i.e., methanol, ethanol, and propanol. A red shift of the dip in the transmission spectrum was observed for increasing values of the refractive index. Compared to the conventional wavelengths, expanding the functionality of optical fiber sensors to the mid-infrared spectrum has the potential to improve sensitivity
Design of a Broadband Erbium-Doped Fluoroindate Fiber Laser Emitting Up to 3.91 μm
No full textIn this paper, for the first time, an erbium-doped fluoroindate fiber laser emitting up to 3.91 μm is designed and optimized by means of a numerical investigation performed via a home-made computer code. It is cladding pumped with red light at 635 nm. The employed fiber is commercially available from Le Verre Fluoré and exhibits a double D-shaped geometry. Continuous-wave laser emission is obtained thanks to the population inversion between the 4F9/2 and 4I9/2 energy levels. The model takes into account measured spectroscopic parameters for the absorption, stimulated emission and spontaneous decay processes. The device performance is investigated by varying several parameters, such as the input pump power, the fiber length, the dopant concentration, the output mirror reflectivity and the signal wavelength. The proposed device is very versatile and is optimized for different scenarios, including: the shortest fiber, the highest output power and the lowest threshold. Simulation results show that the best performance in terms of emission bandwidth is obtained for the laser with the lowest threshold, i.e. only 25 mW, predicting a broadband coherent emission in the 3.25-3.91 μm wavelength range and paving the way to the fabrication of a low-cost and easy-to-pump middle infrared fiber laser
Mode-Group Selective Photonic Lantern based on Indium Fluoride Optical Fibers for Mid-Infrared
No full textThis manuscript illustrates the design and characterization of the first fiber-based photonic lantern, tailored for an efficient operation in the Mid-Infrared spectral range. The design and fabrication of the proposed device involve the use of three distinct indium fluoride optical fibers into a surrounding low refractive index glass capillary. An adiabatic transition is achieved through a controlled manufacturing process based on heating and drawing. The modal behavior of the photonic lantern is investigated along the transition via electromagnetic modal analysis, at the wavelength λ = 3.34 μm. Mode-group selectivity is obtained through the use of optical fibers with different characteristics. This implies that the light launched into a particular optical fiber evolves into specific mode groups at the photonic lantern multi-mode end. Experimental results demonstrate the possibility to excite the LP01 mode and two, odd and even, LP11 propagation modes, with losses below 1.3 dB and 1.7 dB, respectively. These results emphasize the feasibility of the proposed photonic lantern based on indium fluoride glass, with potentials for diverse applications, e.g. in communications, astrophotonics, remote sensing and spectroscopy
Fused optical fiber combiner based on indium fluoride glass: perspectives for mid-IR applications
No full textFor the first time, to the best of our knowledge, the design and characterization of a 3 × 1 fused fiber combiner based on multimode step-index fluoroindate optical fibers (InF3) has been performed. Several efforts to develop a well-consolidated normalization procedure and a fabrication protocol have been required due to the low melting temperature and the mechanical properties of fluoroindates. Fabrication results demonstrate repeatability and absence of crystallization. Therefore, the described fabrication process paves the way for manufacturing fluoroindate devices. The electromagnetic design of the combiner is carried out through modal investigation and beam propagation method by computing the transmission efficiency. The experimental results agree with the simulation and demonstrate the device feasibility to operate in the mid-infrared spectral range
Mid-infrared interferometry with non-adiabatic tapered ZBLAN optical fiber
No full textThis work illustrates, to the best of our knowledge, the first non-adiabatic tapered single-mode zirconium fluoride optical fiber sensor in the mid-infrared spectral range. It is designed and fabricated via pulling and heating technique. A waist diameter dw = 25 μm with no visible crystallization is achieved, overcoming the typical fluoride glass challenges associated with crystallization, narrow temperature fabrication window, and low glass transition temperature. The performance of the non-adiabatic tapered optical fiber is theoretically and experimentally investigated, demonstrating its high potential for a wide range of sensing applications in the mid-infrared spectral range
Mid-Infrared Supercontinuum Generation in ZBLAN Fluoride/Fluoroindate Fibers at Wavelength
No full textIn this paper, the optical properties of available-on-market fluoride glass fibers are examined in order to understand their potentialities in a lot of application areas. The investigation is made with reference to several glass characteristics, in order to appreciate how the change of ZBLAN chemical composition can be exploited to tailor the refractive index and the dispersion. Higher order dispersion coefficients are calculated and are inserted in a home-made computer code in order to simulate supercontinuum (SC) generation in ZBLAN fibers, by using the generalized nonlinear Schrödinger equation (GNLSE) at an emission wavelength equal to 2.9 μm, which is typically used for medical application. As first result, a broadband spectrum extending beyond 4.4 μm is predicted
Design of a Mid-IR Laser Based on a Ho:Nd-codoped Fluoroindate Fiber
No full textIn this work, a novel mid-infrared continuous wave laser, based on a fluoroindate fiber co-doped with holmium and neodymium, is designed to emit at λ s = 3.92 μ , when pumped at λ p = 808 nm. The laser is modeled considering a nine-level system, by taking into account experimental spectroscopical parameters. Since the energy transfer coefficients are unknown, they have been evaluated starting from the measured emission spectra of the bulk glass, reported in literature, and comparing their ratio with respect to the ratio between the simulated signal gain coefficients. The designed laser promises higher slope efficiency and power threshold lower than those obtainable with a holmium-heavily-doped fiber, having same fiber section geometry, same refractive indices and pumped at λ p = 888 nm. Slope efficiency η = 16.67 % and input power threshold Pth = 0.2 W are obtained for the fiber length Lfiber = 0.4 m, dopants concentrations NHo = 8 × 1026 ions m3 and N Nd = 1 × 1026 ions m3, and output mirror reflectivity R out = 60%. This result encourages the fabrication of a continuous wave laser based on a Ho:Nd-codoped fluoroindate fiber
Dual-gas quartz-enhanced photoacoustic spectroscopy sensor exploiting two fiber-combined interband cascade lasers
No full textIn this work, a novel indium fluoride glass 2-input-1-output fiber combiner was designed and fabricated to combine two Interband Cascade Laser (ICL) sources emitting in the mid-infrared wavelength range. To test the combiner performance, a dual-gas quartz-enhanced photoacoustic spectroscopy sensor was demonstrated for the detection of carbon dioxide (CO2) and nitric oxide (NO), employing two fiber-coupled ICLs having central emission wavelengths of 4,234 nm and 5,263 nm, respectively. The laser beams were coupled via the fiber combiner and then focused into a commercial acoustic detection module equipped with an input fiber-port, thus resulting in a plug-and-play sensing system. Tens of ppm-level detection limits at 3σ are achieved for both pollutants with a lock-in integration time (τ) of 0.1 s. Finally, an Allan-Werle analysis demonstrated the stability of the sensor, allowing the achievement of detection limit of 13 ppm and 4 ppm at τ = 10 s for CO2 and NO, respectively
Étude des propriétés électriques et structurales de verres de sulfures au lithium pour électrolytes de batteries tout-solide
No full textThe energy storage market is in constant growth for both portable and stationary applications. To satisfy the requirements of various applications (electronic devices, hybrid-electric vehicles, renewable energy storage…), always more efficient, more compact and lightweight batteries have to be developed. Then, thanks to their high energy densities, batteries using Li metal anodes are the most promising to complete this challenge. However, the use of conventional liquid electrolytes raises safety issues, mainly related to the flammability of the organic liquid. In this thesis, glassy materials, exhibiting great interest towards developing solid electrolytes are considered and might enable the development of safe and efficient all-solid-state batteries. Here, Li-sulfide glasses, attractive for their ionic conduction properties, have been studied and characterized. The ionic conduction properties of glasses are still misunderstood and controversial, the structural investigation of glasses is of great interest in order to get a better understanding of structure-properties relationship. Then, the short and intermediate range order of prepared glasses have been investigated by the mean of various complementary structural analysis techniques. Finally, glassy materials are usually quite easy to shape. Thus, studied glasses in this thesis can also be used as thin-film electrolytes in microbatteries. First tests of sputtering of conducting thin-films have been performed by RF magnetron sputtering and constitute a first step in order to design microbatteries.Le marché du stockage de l'énergie est en perpétuelle expansion, tant pour les applications nomades que fixes. Afin de répondre aux exigences requises pour les diverses applications (appareils électroniques, véhicules hybrides et électriques, stockage des énergies renouvelables…), des batteries toujours plus performantes, compactes et légères doivent être développées. Pour cela, les batteries utilisant du lithium métallique en tant qu'anode sont les plus attractives en termes de densités d'énergies. Néanmoins, l'utilisation d'électrolytes liquides conventionnels, généralement des solvants organiques inflammables, dans de tels dispositifs soulève des problématiques de sécurité. Les travaux de recherche présentés dans ce manuscrit concernent l'étude de matériaux vitreux pouvant être utilisés en tant qu'électrolyte solide afin de permettre le développement de batteries tout-solide sûres et performantes. Des verres de sulfures au lithium, attractifs pour leurs propriétés de conduction ionique, sont étudiés et caractérisés. Les propriétés de conduction ionique dans les verres étant toujours mal comprises et sujettes à controverses, l'analyse structurale des verres présente ici un réel intérêt pour une meilleure compréhension des corrélations entre structure et propriétés. Un effort de recherche a donc été porté sur l'étude de l'ordre local dans les verres préparés via différentes techniques d'analyse structurale complémentaires. Enfin, les matériaux vitreux, sont de manière générale relativement faciles à mettre en forme. Les verres étudiés dans ce manuscrit peuvent alors également être utilisés en tant qu'électrolytes sous forme de couches minces dans les micro-batteries. Des premiers essais de dépôts par pulvérisation cathodique RF magnétron de couches minces conductrices ont donc été effectués et constituent la première brique à la fabrication de micro-batteries
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