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Near resonant nanosecond laser-driven nonlinear optical response in As <sub/>50</sub> S <sub/>50</sub> thin films
摘要： Nanosecond near resonant excitation in As50S50 thin films leads to strong nonlinear optical response, i.e. nonlinear absorption coefficient up to 4 × 106 cm GW?1 and nonlinear refractive index of 8.5 cm2 GW?1, both of which are the strongest ever reported in amorphous semiconductors. We propose a three-level energy band model to explain this effect, which indicates that the nonlinear process is reverse saturable absorption in nature, mediated by excited-state absorption from slow interband transition between the conduction and valence band. On the other hand, observation of negative nonlinear refractive index reveals the occurrence of self-defocusing effect. Finally, benefitting from the strong nonlinear response, we demonstrate a promising application of As50S50 thin films as an optical limiter for optoelectronic sensors.
关键词： chalcogenide,nonlinear optics,Z-scan,thin films
更新于2025-09-19 17:13:59
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Milliwatt-Level Spontaneous Emission Across the 3.5a??8 ?μm Spectral Region from Pr3+ Doped Selenide Chalcogenide Fiber Pumped with a Laser Diode
摘要： A spontaneous emission fiber source operating in the mid-infrared (MIR) wavelength range from 3.5 to 8 μm is demonstrated for the first time at output power levels of at least 1 mW. The source is a Pr3+-doped selenide chalcogenide, multimode, glass fiber pumped with commercially available laser diodes operating at 1.470 μm, 1.511 μm and 1.690 μm. This MIR spontaneous emission fiber source offers a viable alternative to broadband mid-infrared supercontinuum fiber sources, which are comparatively complex and costly. The MIR emission wavelength range is significant for molecular sensing applications across biology and chemistry, and in medicine, agriculture, defense, and environmental monitoring.
关键词： mid-infrared,mid-infrared light sources,fiber lasers,chalcogenide glass fibers
更新于2025-09-19 17:13:59
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[IEEE 2019 Workshop on Recent Advances in Photonics (WRAP) - Guwahati, India (2019.12.13-2019.12.14)] 2019 Workshop on Recent Advances in Photonics (WRAP) - Picosecond Fundamental Soliton Pulse Compression in Self-similarly designed Chalcogenide Taper Photonic Crystal Fiber
摘要： We numerically demonstrate a pulse compression scheme to compress picosecond fundamental soliton at 2500 nm using Self-similarly designed chalcogenide tapered photonic crystal fiber. Exponentially decreasing dispersion along the length of the fiber act as a tool for the compression process. Dynamics of propagating fundamental soliton has been studied by utilizing nonlinear Schr?dinger equation. Quality analysis has also been investigated for different fiber length to achieve efficient compression condition to achieve high quality IR regime pulses.
关键词： Photonic crystal fiber,Chalcogenide fiber,Supercontinuum generation,Pulse Compression,self-similar Analysis
更新于2025-09-19 17:13:59
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Temperature dependent structural evolution and crystallization properties of thin Ge<sub>15</sub>Te<sub>85</sub> film revealed by in situ resistance, X-Ray diffraction and scanning electron microscopic studies
摘要： Chalcogenide-based Ge15Te85 thin films have recently been explored for Ovonic threshold switching (OTS) selector devices for vertically stackable cross-point memory applications. Despite reasonable understanding over its crystallization kinetics and threshold switching properties, the structural stability and morphological acquaintance at elevated temperatures remain key challenges. In this paper, we investigate the thermal stability, surface morphology and local structure of as-deposited amorphous Ge15Te85 thin film starting from room temperature up to 325 °C. Our experimental results reveal that upon heating, the de-vitrification is initiated in the form of localized segregation of Te atoms at 120 °C, followed by crystallization of Te at ~ 220 °C and GeTe at ~ 263 °C as corroborated by temperature- dependent measurements of electrical resistance, X-ray diffraction and scanning electron microscopic studies. Furthermore, the crystalline areas of these films are characterized by the fine-grained morphology, which clearly distinguishes the segregation of crystallization of Te and GeTe microstructures. These findings elucidate a deeper understanding of the multi-phase crystallization process through morphological evidence, which will be useful towards optimization of materials for Ovonic Threshold Switch (OTS) selector applications.
关键词： Chalcogenide thin films,phase change material,OTS Selector,Scanning electron microscopy,Ge15Te85
更新于2025-09-19 17:13:59
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Controlled nanoa??crystallization of IR frequencya??doubling Cd <sub/>4</sub> GeS <sub/>6</sub> crystal in chalcogenide glass
摘要： Crystallization of IR frequency-doubling nanocrystals in chalcogenide glasses is a promising approach to achieve novel nonlinear optical materials. However, controllable glass crystallization remains challenging. In this study, IR-transparent chalcogenide glass-ceramics containing novel Cd4GeS6 IR frequency-doubling na- nocrystals (about 60-80?nm) are fabricated through controlled nano-crystallization. Nanocrystalline structure of the Cd4GeS6 nano-crystallized glass-ceramics is inves- tigated in detail through X-ray diffractometer, field emission scanning electron mi- croscope, and Raman scattering techniques. The structural similarity of [Cd4GeS6] polyhedron in the network structure of as-prepared glass is found to be responsible for the nucleation of Cd4GeS6 crystal. A unique microstructure of Cd4GeS6 nanocrys- tals embedded GeS2 phase-separated structure is discovered in samples thermally treated at high temperatures (370°C and 380°C). This study would not only shed more light on glass crystallization mechanism but also provide a feasible approach for the design and fabrication of new IR frequency-doubling materials through glass crystallization.
关键词： Cd4GeS6,microstructure,glass-ceramics,chalcogenide glasses,crystallization
更新于2025-09-19 17:13:59
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Hollow/porous-walled SnO2 via nanoscale Kirkendall diffusion with irregular particles
摘要： Hollow/porous structured SnO2 nanoparticles were synthesized by simple oxidation of dense metal chalcogenide precursors via nanoscale Kirkendall diffusion effect. First, tin chalcogenide (SnS, SnSe) nanoparticles were synthesized by mechanochemical method, which is considered a facile, scalable, and eco-friendly process. Hollow/porous-walled SnO2 nanoparticles were synthesized by simple oxidation of the prepared Sn chalcogenide precursors, for which the transformation mechanism was verified in detail. Nanoscale Kirkendall diffusion process was thoroughly investigated by morphological, crystallographic, and elemental analyses performed at various oxidation temperatures and times. To examine the morphological effect of hollow/porous-walled SnO2 nanoparticles on the electrochemical performance, the synthesized nanoparticles were applied as anode material in a lithium-ion battery. Anode material showed highly improved electrochemical properties compared to its dense counterpart, with 83% capacity retention from the second cycle at the 400th cycle and capacity of 302 mA h g-1 at a high current density of 30 A g-1.
关键词： chalcogenide,hollow structure,mechanochemical synthesis,porous particles,Kirkendall effect
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - In Situ Fabrication of Far-Detuned Mid-Infrared Optical Fiber Wavelength Converters
摘要： In Situ Fabrication of Far-Detuned Mid-Infrared Optical Fiber Wavelength Converters. Chalcogenide (ChG) glasses have been identified as promising materials for applications in nonlinear photonics due to their exceptionally high nonlinear refractive index; nearly three orders of magnitude beyond that of silica glass. A ChG fiber or waveguide that is tapered down into a microwire provides strong light confinement and enhanced nonlinear optical effect, it allows engineerable chromatic dispersion and thereby an easy access to nonlinear parametric processes such as four-wave mixing (FWM). In well-controlled conditions of chromatic dispersion ChG microwires may lead to strong parametric gain that is far-detuned with respect to the pump wavelength, by tens of THz [1,2]. In theory, chromatic dispersion in a waveguide is precisely adjusted from a good control of waveguide geometry. In practice however, the amount of precision required in waveguide geometry as well as errors on the evaluation of refractive indices prevent the fabrication of wavelength converters with a predetermined wavelength offset. To illustrate this, fig. 1(a) shows the theoretical spectrum of a far-detuned ChG wavelength converter. A change in the core diameter by 5 nm results in a ~ 40 nm wavelength shift of the parametric sidebands. As an element of solution inspired from past reports, it has been shown with supercontinuum generation that experimental parameters could be finely tuned using an in situ monitoring technique [3]. In this work, we demonstrate that wavelength conversion of a ChG microwire is precisely attained by in situ tracking of the microwire output during the tapering process, enabling the fabrication of wavelength converters that are precisely far-detuned by at least 34.3 THz.
关键词： four-wave mixing,nonlinear photonics,in situ tapering,Chalcogenide glasses,wavelength conversion
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Analysis of Various Approaches for the Fabrication of Diffractive Optical Elements
摘要： Diffractive Optical Elements (DOEs) exist for a large range of applications. Usually DOEs are obtained by combining lithographic techniques and etching in order to achieve pre-determined phase patterns. That way, it is possible to shape or split laser beams with very high efficiencies. Indeed for binary element which consist of two phase levels (0 and π) the diffraction efficiency is around 75% and this efficiency can approach 100% for multilevel elements. Various illustrations of DOEs can be found in the literature for example using organic materials like photoresists or inorganic materials such as silica or chalcogenide layers. Recent work has shown that DOEs can also be recorded in the volume of photosensitive chalcogenide layers, but no precise comparison of this class of DOEs has ever been made with classical DOEs. In this paper we propose to study binary DOEs fabricated with conventional lithography (based on local control of the thickness) and similar one fabricated using photo-induced refractive index change in As2S3 layers.
关键词： etching,phase patterns,silica,laser beams,photo-induced refractive index change,photoresists,lithography,As2S3 layers,chalcogenide layers,Diffractive Optical Elements,diffraction efficiency
更新于2025-09-16 10:30:52
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Influence of Se on Properties of As-S-Se-I Glass for Immersion Mid-IR Leds Lenses
摘要： The study of glass components influence on the physical and chemical properties of As–S–Se–I glasses has the potential to help design glasses with the required properties. A change of certain glass properties upon the introduction of selenium into AsSI glass was demonstrated. Non-stoichiometric compounds along the As2S3-AsI3-Se diagram section were investigated by differential thermal analysis, ultrasonic measurements, dilatometric measurements. It has been shown that the introduction of selenium decreases the glass solubility in water. Change in the glass properties with the change in the short-range structure studied by Raman spectroscopy was shown. These glasses can be used for creation of immersion lenses and optical adhesives which change radiation characteristics of mid-IR LEDs.
关键词： coefficient of thermal expansion,mechanical characteristics,density,solubility,chalcogenide glass,Raman spectra
更新于2025-09-16 10:30:52
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Impact of composition and ex-situ laser irradiation on the structure and optical properties of As-S-based films synthesized by PECVD
摘要： Synthesis of amorphous chalcogenide As-S-based films with arsenic content from 35 to 55 at. % by a PECVD method is achieved. The composition-structure-optical properties relationship is revealed. Varying the composition of the films from As35S65 to As55S45 is accompanied by a change of the dominant structural units: from AsS3/2 pyramids to cage-like As4S4 and As4S3 units, causing a considerable decrease of the optical band gap from 2.42 to 1.87 eV. It has been found out that modification by a focused laser irradiation (473 nm) leads to formation of micro/nanocrystalline inclusions feasible for applications in medicine, optoelectronics and integrated optics. The type of inclusions depends on the dominant structural units of the initial films. In case of the As55S45 film appearance of the dimorphite crystalline phase (α-As4S3) is observed. The ex-situ laser modification of the As-S films leads to appearance of a photoluminescence emission, and its maximum position shifts from 1.8 to 2.05 eV depending on the initial film stoichiometry.
关键词： Optical properties,Arsenic sulfide,Chalcogenide films,Nanocrystals formation,PECVD
更新于2025-09-16 10:30:52