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Investigations of physical parameters of Ge doped binary Se-As chalcogenide glassy alloys for optical fiber application
摘要： Germanium doped chalcogenide glasses have potential applications in non- linear and optoelectronic devices. Ternary Ge-Se-As system has been considered to study the different important physical parameters. The impact of deviation of Ge on the cost of As in Ge-Se-As glassy system has been discussed in terms of average coordination number, cohesive energy, heat of atomization, and the theoretical optical band gap of the system. Almost all the physical parameters are found to change linearly with the variation in Ge content. The physical properties approximated in the present study can reveal the structural details for optical fibers.
关键词： Chalcogenide glasses,cohesive energy,mean bond energy,glass transition temperature,lone pair electrons
更新于2025-09-16 10:30:52
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Cd(Zn, S)Se quaternary thin films for electrochemical photovoltaic cell application
摘要： In this study, Cd1?xZnxSySe1?y (0 ≤ x = y ≤ 0.35) photoelectrodes are deposited via inexpensive facile chemical bath deposition. The effects of Zn and S doping on the compositional, microstructural, electrical, and optical properties of thin films were analysed. The electrochemical photovoltaic (EPV) cell of configuration Cd1?xZnxSySe1?y/0.25M sulfide/polysulfide/C was assembled to examine the different performance parameters in light and in dark conditions. An EPV cell fabricated with the Cd1?xZnxSySe1?y (0 ≤ x = y ≤ 0.075) photoelectrode exhibited a maximum photoconversion efficiency of 3.18%. This performance can be attributed primarily to the enhanced light-absorption ability of the material because of the enhanced rough microstructure and low recombination of photo-injected electrons with the electrolyte. The photovoltaic (PV) performance is significantly enhanced after doping CdSe with Zn and S.
关键词： EPV cells,hall effect,multinary materials,energy bandgap,electrostatic force microscopy,thin film electrodes,chalcogenide semiconductors,Fermi level
更新于2025-09-16 10:30:52
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Lead chalcogenide quantum dots for photoelectric devices
摘要： The review concerns the state of the art in methods of synthesis of colloidal lead chalcogenide quantum dots (QDs). The most recent data on the mechanisms of chemical transformations involving various precursors are discussed. Particular attention is paid to the influence of (i) trace impurities in the reactants used and (ii) post-synthesis treatment on the physicochemical properties of QDs used in photoelectric devices. The bibliography includes 129 references.
关键词： photoelectric devices,quantum dots,colloidal synthesis,lead chalcogenide,synthesis methods
更新于2025-09-16 10:30:52
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Rationally designed CuSb1-Bi S2 as a promising photovoltaic material: Theoretical and experimental study
摘要： Here we report the miscibility gap of CuSb 1- x Bi x S 2 (CABS), a promising photo energy conversion material for band gap engineered solar cells, and evaluate its applicability via a combination of theoretical predictions and experimental verifications. Our ab initio calculations and thermodynamic modeling revealed that the CABS random alloy system has optimal band gap values in the range of 1.1–1.5 eV when synthesized at room temperature. The CABS system, synthesized by mechanochemical methods, exhibited optical band gap values in very good agreement with theoretical predictions, as well as lowered kinetic energy barriers for enhanced nucleation.
关键词： Photovoltaic materials,Chalcogenide,Mechanochemical method,Solar cells,I–V–VI
更新于2025-09-16 10:30:52
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Laser-induced optically modified Se <sub/>58</sub> Ge <sub/>27</sub> Pb <sub/>15</sub> and Se <sub/>58</sub> Ge <sub/>24</sub> Pb <sub/>18</sub> thin films
摘要： Amorphous samples of Se58Ge27Pb15 and Se58Ge24Pb18 glasses were prepared using the melt quenching method. Thin films of samples were deposited using the vacuum evaporation method. These films were illuminated with Nd: YAG 532 nm green laser radiation. The samples were structurally characterised using X-ray Diffraction (XRD) and Energy-dispersive X-ray analysis. XRD indicated an increase in the crystallinity of samples on laser irradiation. The samples were optically tested through absorption, reflection and transmission spectra recorded on UV-vis spectrophotometer. The obtained values of energy band gap, refractive index, extinction coefficient and Urbach energy of the films were compared both before and after laser exposure. Furthermore, it was found that sample thickness also changes on laser irradiation. The band gap of the samples was found to decrease laser irradiation in Se58Ge27Pb15thin films, while for Se58Ge24Pb18 thin film samples, an unexpected increase in band gap was observed at a laser irradiation time of 8 min. The variable behaviour of band gap has been explained on the basis of Mott and Davis model and heteropolar bond formation.
关键词： thin films,laser irradiation,Chalcogenide glasses,optical properties
更新于2025-09-12 10:27:22
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Design and Analysis of a Dispersion-engineered and Highly Nonlinear Rib Waveguide for Generation of Broadband Supercontinuum Spectra
摘要： In this paper, a waveguide consisting of a core of As2Se3 chalcogenide glass and the upper and lower claddings of MgF2 with two zero-dispersion wavelengths (ZDW) has been proposed. By optimization of the dimensions of the core and the claddings, their effects on the dispersion curve have been investigated and a suitable structure with a flat dispersion curve, an effective mode area of 1.6 μm2 in a pump wavelength of 2.8 μm, and hence, a nonlinear coefficient greater than 34 w?1 m?1 has been obtained. A broadband supercontinuum in a wavelength range of 1.5 μm to 15 μm has been generated by applying an input pulse with duration of 100 fs and a maximum power of 2 kw to this waveguide. Due to the large width of the supercontinuum generated (SCG), the short length of the waveguide (maximum 5 mm), and a low input power, this structure is suitable for use in optical integrated circuits and its various applications.
关键词： zero dispersion wavelength,supercontinuum generation,high nonlinearity,chalcogenide glass,low loss,rib waveguide
更新于2025-09-12 10:27:22
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Type-II heterostructures of <b>α</b> -V <sub/>2</sub> O <sub/>5</sub> nanowires interfaced with cadmium chalcogenide quantum dots: Programmable energetic offsets, ultrafast charge transfer, and photocatalytic hydrogen evolution
摘要： We synthesized a new class of heterostructures by depositing CdS, CdSe, or CdTe quantum dots (QDs) onto α-V2O5 nanowires (NWs) via either successive ionic layer adsorption and reaction (SILAR) or linker-assisted assembly (LAA). SILAR yielded the highest loadings of QDs per NW, whereas LAA enabled better control over the size and properties of QDs. Soft and hard x-ray photoelectron spectroscopy in conjunction with density functional theory calculations revealed that all α-V2O5/QD heterostructures exhibited Type-II band offset energetics, with a staggered gap where the conduction- and valence-band edges of α-V2O5 NWs lie at lower energies (relative to the vacuum level) than their QD counterparts. Transient absorption spectroscopy measurements revealed that the Type-II energetic offsets promoted the ultrafast (10?12–10?11 s) separation of photogenerated electrons and holes across the NW/QD interface to yield long-lived (10?6 s) charge-separated states. Charge-transfer dynamics and charge-recombination time scales varied subtly with the composition of heterostructures and the nature of the NW/QD interface, with both charge separation and recombination occurring more rapidly within SILAR-derived heterostructures. LAA-derived α-V2O5/CdSe heterostructures promoted the photocatalytic reduction of aqueous protons to H2 with a 20-fold or greater enhancement relative to isolated colloidal CdSe QDs or dispersed α-V2O5 NWs. The separation of photoexcited electrons and holes across the NW/QD interface could thus be exploited in redox photocatalysis. In light of their programmable compositions and properties and their Type-II energetics that drive ultrafast charge separation, the α-V2O5/QD heterostructures are a promising new class of photocatalyst architectures ripe for continued exploration.
关键词： α-V2O5 nanowires,cadmium chalcogenide quantum dots,photocatalytic hydrogen evolution,programmable energetic offsets,Type-II heterostructures,ultrafast charge transfer
更新于2025-09-12 10:27:22
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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) - All — Fiber Evanescent Wave Sensors for the Mid-Infrared Spectroscopy of Liquids
摘要： Methods of the mid-IR spectroscopy provide reliable tools for detecting chemical composition of gases and liquids. In the mid-IR spectral range (wavelengths of 3-25 μm), various molecules and functional groups have fundamental absorption bands with large absorption coefficients. Creation of materials and technologies for the remote sensors consisting of fiber-optic broadband sources of coherent mid-IR radiation, chalcogenide fibers for transmitting light to the sensing elements and spectrally-selective photodetectors is a problem of a high scientific priority. In this work, we develop the fiber-optic analytical spectroscopy for chemical analysis of aqueous solutions of acetone, ethanol, for determination of the fractional chemical composition of hydrocarbons. As a material base for the fiber-optic sensors, chalcogenide fibers with an extremely low content of impurities have been designed and fabricated by single- and double-crucible methods (including the REE-doped glass fibers). By using these fibers, technologies of fabrication of permanent fiber bends, tapers, microstructured fibers have been developed for using these structures in fiber lasers, supercontinuum generators, sensing elements. A theoretical approach based on electromagnetic theory of optical fibers has been applied for computer-aided design of the evanescent-wave sensors. A sensing element shaped as the U-bent fiber that was applied for chemical analysis of liquid consisting of a diesel oil and a fuel additive is shown. For chemical analysis, the absorption band at the wavelength of 7.83 μm, corresponding to esters, has been chosen. Output characteristics of the sensor were studied in experiment by variation of the fiber core diameter and the bend radius. In a computer model, it was shown that attenuation coefficients of evanescent modes propagating in the fiber bend grow with increase of the bend radius and with decrease of the fiber core diameter. This allows for enhancing sensitivity and decreasing the minimum detectable amount of an analyte. In fact, with an optimised sensing element, the minimum detected amount of the fuel additive was less than 0.1 vol.%.
关键词： evanescent-wave sensors,chalcogenide fibers,chemical analysis,fiber-optic sensors,mid-IR spectroscopy
更新于2025-09-12 10:27:22
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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) - Chalcogenide Glass Polarization-Maintaining Photonic Crystal Fiber for Mid-Infrared Supercontinuum Generation
摘要： Chalcogenide-glass-based optical fibers are excellent photonic platforms for nonlinear applications in the mid-IR region due to their wide transmission window, tunable dispersion and high optical nonlinearity. There is particular interest in combining the chalcogenide fiber platform with polarization-preserving properties as this will allow polarization-dependent measurements while minimizing detrimental effects and thus enable new applications in interferometric techniques, gas sensing, integrated-optic devices and optical coherence tomography. In this work, for the first time to our knowledge, we demonstrate mid-IR supercontinuum (SC) generation in a highly birefringent polarization maintaining photonic crystal fiber (PM-PCF). The PM-PCF was drawn using the casting method from As38Se62 glass which features a transmission window from 2-10 μm and a high nonlinear refractive index up to 1.13×10-17 m2/W [1,2]. To introduce strong birefringence, an asymmetric arrangement of air holes was used as shown in Fig. 1(a). The PCF cross section consists of 36 circular air holes in 3 rings with 2 larger air holes adjacent to the core. The (approximate) core diameter (i.e. distance between two large air holes) is ~8.1 μm and the outer diameter of the PCF is 125 μm. The group velocity dispersion and group birefringence for the fundamental mode (computed from the SEM image) are shown in Fig. 1(b). The fiber has a zero-dispersion wavelength around 4.5 μm and, at this wavelength, a large birefringence of 6×10-4 such that strong polarization maintaining properties are expected. In our experiments, a 25cm long PM-PCF was pumped with 250 fs pulses at 4 μm (i.e. the normal dispersion regime) using the same experimental setup for MIR SC generation as previously described in Ref. [3]. Figure 1(c) shows the generated SC spectra with different output power. For a pump power of 135 mW, we obtained a SC spectrum from 3.1-6.02 μm with an average output power of 11 mW. Pumping close to the zero dispersion wavelength with the pump at 4.53 μm yielded comparable spectral broadening but at much lower input pump power of 62 mW as shown in Fig. 1(d). In this case, we were able to measure the polarization dependence of the SC spectra by changing the coupling angle through rotation of the fiber. These results demonstrate the potential of chalcogenide PM-PCF for polarized SC generation, and work is underway to optimize the spectral generation and polarization dependency using detailed numerical modelling.
关键词： Polarization-maintaining,Photonic crystal fiber,Chalcogenide glass,Mid-infrared,Supercontinuum generation
更新于2025-09-12 10:27:22
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Creation of shuttle-shaped nanoparticles using the method of magnetic polarization pulse laser ablation
摘要： The GaxCo0.6-xZnS0.4 (x = 0.1, 0.3, 0.5) nanoparticles with shuttle-shaped are fabricated via a Magnetic Polarization Pulse Laser Ablation (MPPLA) method. Meanwhile, the circular-shaped nanoparticles also are prepared for comparative analysis. The particle size, structure, and valence state are systematically investigated by X-ray di?raction (XRD), Raman spectra and X-ray photoelectron spectroscopy (XPS). The morphology of the nanoparticles characterized by TEM indicating the high e?cient of shuttle-shaped particles in preparation. A physical model of the e?ect of magnetic ?eld on the plasma plume is established to explain the formation of shuttle-shaped nanoparticles. Then, we present an explosion-absorption model to demonstrate the growth mechanism of nanoparticles. We further discuss the cluster phenomena and summarized three types of clusters in our nanoparticle suspensions. Fluorescence properties are re?ected by PL spectra, which demonstrates the best performance in concentration of GaxCo0.6-xZnS0.4 with shuttle-shaped. Therefore, all the results suggest that MPPLA is promising to prepare nanoparticles since it can adjust the shape, solve the cluster and modulate performance of NPs.
关键词： PLA,Chalcogenide,Magnetic Polartzation,Nanoparticles
更新于2025-09-11 14:15:04