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Infrared radiation Induced attenuation of radiation sensitive optical fibers: influence of temperature and modal propagation
摘要： We investigate the X-ray (40 keV) and γ-ray (1.2 MeV) radiation responses of three different radiation sensitive Optical Fibers (OFs) up to 100 Gy(SiO2). In particular, we study the Radiation Induced Attenuation (RIA) in the Near Infrared domain (NIR) for single mode OFs doped with Phosphorus (P), Aluminum (Al) and Phosphorus/Cerium (PCe) in their cores at three temperatures up to 50 °C. RIA levels and kinetics strongly depend on the operating wavelength and fiber composition. For both P and PCe-doped fibers, the P1 defects are the main contributors to the RIA, with Ce-codoping inducing a decrease of radiation sensitivity. For the Al-doped fiber, no specific absorption bands can be discriminated in the NIR. Both X- and γ-rays lead to the same RIA levels and kinetics. The RIA spectral dependences on dose and temperature highlight the potential of the three investigated fibers for radiation detection and dosimetry. To better discuss the properties of point defects responsible for the NIR RIA, we analyze how the fundamental mode propagation influences the RIA spectra of each fiber type. By reasonably assuming that the core RIA exceeds largely the cladding RIA and by calculating the mode Confinement Factor (CF), the RIA spectra of the core material are reconstructed and the spectral characteristics of defects are discussed for each type of fibers.
关键词： Radiation Induced Attenuation,Aluminum,Optical fiber,Phosphorus,Cerium
更新于2025-09-23 15:19:57
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Effect of Strontium Doping on the Band Gap of $$\hbox {CeO}_{2}$$ CeO 2 Nanoparticles Synthesized Using Facile Co-precipitation
摘要： Pure, 3 mol% and 5 mol% Sr-doped cerium oxide nanoparticles were synthesized by facile aqueous co-precipitation method using cerium nitrate hexahydrate and strontium chloride hexahydrate as the precursors without using any capping agent. The synthesized material was characterized by XRD, SEM, EDX, TEM, Raman spectroscopy and UV–Vis spectroscopic techniques. SEM analysis showed agglomeration of the particles. The Debye–Scherrer analysis revealed ?uorite structure of the synthesized material with crystallite size in 6–10 nm range. TEM con?rmed the spherical morphology of the particles and particle size distribution in the range of 5–8 nm. UV–Vis spectroscopic study revealed that Sr-doping led to increase in the band gap from 3.2 to 3.7 eV and shifting of absorption edge to the lower wavelength. The blue shift in the band gap with the dopant concentration shows that the band gap of doped cerium oxide nanoparticles can be tuned with variation in the dopant concentration.
关键词： Sr-doped cerium oxide,Blue shift,Band gap
更新于2025-09-19 17:15:36
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Highly efficient photocatalytic degradation of rhodamine B by conical graphene quantum dots/cerium oxide composite
摘要： Graphene Quantum Dots (GQDs) are graphene nanoparticles with a particle size of less than 100 nm. GQDs are used as sensitizers for semiconductor catalytic materials and have a significant enhancement effect on the catalytic performance of the catalyst. We have prepared GQDs/CeO2 composites to improve the catalytic performance of CeO2. GQDs in the GQDs/CeO2 composites were uniformly coated around each CeO2 crystal, which effectively increased the reactive sites and effective contact interfaces. The composite GQDs-4.5/CeO2 absorption edge was broadened to 475 nm, with extremely low electron-hole recombination rate and optimal photoelectric performance. The composite material formed a heterogeneous structure with staggered energy levels. The photogenerated electrons were transferred from the GQDs conduction band to the CeO2 conduction band, which effectively prolonged the carrier lifetime, showed enhanced photocatalytic activity, and decomposed Rhodamine B (RhB) photocatalytic reaction under visible light. The reaction rate constant was up to 13.8 times that of pure CeO2.
关键词： Composite,Photocatalytic,Cerium oxide,Graphene quantum dots
更新于2025-09-19 17:13:59
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Ce:Nd:YAG continuous-wave solar-pumped laser
摘要： The first emission of a Ce:Nd:YAG solar-pumped laser is reported here, to the best of our knowledge. A solar laser head was composed of a fused silica liquid light guide lens and a conical pump cavity, which coupled and redistributed the concentrated solar radiation from the focal zone of a parabolic mirror into a Ce:Nd:YAG laser rod. The laser output performance of the 5 mm diameter, 30 mm length Ce:Nd:YAG laser rod was compared with that from a 5 mm diameter, 30 mm length Nd:YAG rod. With a solar pump power of 569 W, the Ce:Nd:YAG solar laser emitted 6 W continuous-wave power at 1064nm, corresponding to a collection efficiency of 4.9 W/m2. Even though this power level was lower than the 10 W obtained by using the Nd:YAG rod, the Ce:Nd:YAG laser medium may be an alternative active medium for solar-pumped lasers.
关键词： parabolic mirror,Nd:YAG,solar-pumped laser,Ce:Nd:YAG,cerium
更新于2025-09-16 10:30:52
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Radiation Effects in Materials || Effects of Electron Irradiation Upon Absorptive and Fluorescent Properties of Some Doped Optical Fibers
摘要： A review of the recent studies of the effect of irradiating silica-based fibers doped with rare earths and metals by a beam of high-energy (β) electrons is presented. Of the review’s main scope are the attenuation spectra’ transformations occurring in optical fiber of such types under electron irradiation, allowing, from one side, to recover some general essence of the phenomena involved and, from the other side, to draw the features that would make such fibers useful for applications, for example, in dosimetry and space technologies. Among the fibers of the current review’s choice, exemplifying the effect of electron irradiation most brightly, are ytterbium (Yb) and cerium (Ce) (the rare earths’ representatives) and bismuth (Bi) (the post-transitional metals representative) doped fibers, where a diversity of the electron-irradiation-related effects is encouraged.
关键词： optical bleaching,photodarkening,cerium- and bismuth-doped silica fibers,electron irradiation,ytterbium-
更新于2025-09-16 10:30:52
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Physical properties of cerium doped-yttrium iron garnet ultrathin films for photovoltaic application
摘要： In this study, cerium incorporated yttrium iron garnet ultrathin films (CexY3-xFe5O12) (where x = 0, 0.1, 0.3, and 0.5) were prepared by the sol-gel method, spin coating technique, and heat treatment on quartz substrates. The effect of Ce on structural properties, morphology of thin films surface, and optical properties was explored by X-ray diffraction (XRD), field emission microscopy (FESEM), and atomic force microscopy (AFM). According to the XRD results, the films were crystalline with the cubic phase, while the FESEM indicated the YIG nanoparticles with approximately spherical shapes. The growth process of crystallite in YIG nanoparticles was investigated by X-ray peak broadening. The Williamson-Hall (W–H) analysis was utilized to maintain the contributions of crystallite size on the peak broadening of Ce:YIG nanoparticles. The structural features of thin films such as strain and stress for all of the peaks of XRD were accurately determined from the uniform deformation model (UDM) according to the YIG cubic phase. According to the AFM pictures, it seemed that thin films had a continuous and smooth surface. The absorption and transmission were measured in the visible and infrared region from 400 to 1200 nm.
关键词： Structural features,Cerium yttrium iron garnet thin films,Photovoltaic application,Optical properties,Sol-gel
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) - Photo Darkening Suppression in Highly Yb-Doped Aluminophosphosilicate Fiber by Addition of Cerium
摘要： Photodarkening (PD) suppressed low numerical aperture (NA), high absorption, low loss, large mode area (LMA) fiber is an important requirement for high power fiber lasers, in both pulsed and continuous wave operation regimes. We have reported the fabrication of high absorption (~1200 dB/m core absorption) Yb doped aluminophosphosilicate fiber with raised Ge cladding to realize low NA step index fiber [1]. The presence of Aluminium (Al) and phosphorus (P) in the core helps in lowering the PD loss by a significant margin, but some PD loss is still observed. In this work we intend to further lower the PD loss by adding Cerium (Ce) to this equimolar P:Al core. Previous reports suggests that addition of Ce to Yb:Al core significantly reduce the PD loss when the ratio of Ce oxide to Yb oxide ratio is ~0.5-0.7 [2-4]. However, like Yb, Ce has a high molar refractivity, and all dopants (Yb, Ce and Al) push up the core NA. In our work, equimolar P:Al does not contribute to index of the core, and only the Ce and Yb raise the core NA. Furthermore, the reported raised Ge cladding technique can compensate the core NA to a desired level [1]. We here present three fibers with high Yb concentration of ~0.5mol% and with equimolar Al and P composition, all fabricated by modified chemical vapor deposition and solution doping technique. Fiber #1 contains no Ce while Fiber #2 and Fiber #3 contain Ce with different Ce/Yb oxide ratio of ~0.24 and ~0.625, respectively. The index profiles of the three fibers are shown in Fig. 1(a). As expected, the core NA increases with Ce concentration. Compositional concentration profile in Fiber #3 measured by energy dispersive X-ray analysis (EDX) is shown in Fig. 1(b). P2O5, Al2O3, Yb2O3 and CeO2 were found to be around 5 mol%, 4.6 mol%, 0.48 mol% and 0.3 mol% respectively, in the core. Hence the Ce/ Yb oxide ratio was observed to be ~0.625, which according to the reported works is supposed to yield quite good PD suppression while creating no additional thermal issues. All the fibers have similar Yb, Al and P contents with only difference in the Ce concentration. Fiber#2 contains ~0.12mol% of Ce2O3. The background losses in the fibers were found to be <25dB/Km after a cut-back method measurement. This is considered low for fibers with such high Yb concentration. Finally, the fibers were tested for PD loss using core pumped configuration with 634 nm as a probe wavelength and 976 nm as pump wavelength. Population inversion levels of ~45% was maintained in all the fibers. The PD losses for the fibers are shown in Fig. 1(c). Fiber#1, Fiber #2 and Fiber#3 has PD losses of 70 dB/m, 30 dB/m and 7 dB/m respectively. Thus, it can be clearly seen that addition of Ce to Yb doped aluminophosphosilicate fiber reduces PD significantly, with the ratio of Ce:Yb playing a major role as well. In conclusion, we report the first fabrication of Ce and Yb doped aluminophosphosilicate fiber with very high absorption, and extremely low PD.
关键词： Aluminophosphosilicate fiber,Fiber lasers,Yb-doped,Photodarkening,Cerium
更新于2025-09-11 14:15:04
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Systematic enumeration and proficient chemical sensing applications of Eu3+@CeO2 nanocrystals
摘要： Current study displayed the application of hydrothermal method for the preparation of highly crystalline nanocrystals of Eu3+ doped cerium oxide (Eu@CeO2) particles. The influence of doping percentage and annealing effects were studied on the crystalline nature and morphology of particles. The size, optical properties and lattice parameters were calculated as a function of dopant concentrations and their discrepancies were explained in detail. Integration of Eu3+ ions on CeO2 could unlock a new trail to optimize the photoluminescence properties of formed nanocrystals. The generated oxygen vacancies (Vo··) have the ability to affect the characteristic features of cerium oxide in solid state. The variations in the nature of surface defect in presence of Eu3+ ions with CeO2 nanoparticles were explained with the results of XPS studies. The obtained results validated that defect-induced band gap modification by Eu3+ ion doping on CeO2 could be employed as effective chemical sensor for harmful metal ions in real water samples.
关键词： photoluminescence,lattice parameter,crystalline,doped Cerium oxide,oxygen vacancies,hydrothermal
更新于2025-09-11 14:15:04
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Role of Cerium Doping on Epitaxial Yttrium Iron Garnet Thin films
摘要： The present work discusses the growth optimization and magnetic properties of the Cerium doped Yttrium Iron Garnet (YIG) thin films grown through Pulsed Laser Deposition technique. The X-ray diffraction (XRD) reveals the highly crystalline, Single Phase, nature of films and the Atomic Force Microscopy (AFM) shows the films are very smooth, with root mean square roughness of less than 1 nm. Thickness of the films as calculated from the X-ray reflectivity (XRR) was found to be around 17, 35, 52, 70 and 122 nm. The Magnetic measurement shows the increase in the Saturation Magnetization, in the cerium doped YIG, but as the growth time increases, we observed a decrease in magnetic Saturation. The decrease in saturation magnetization arises due to the formation of residual Ce2O phase in the longer grown films. Longitudinal Spin Seebeck Voltage signal was observed in the films and the Platinum (Pt) deposited over the Cerium doped YIG film showed no sign of Pt magnetization.
关键词： Microwave technology,Surface topography,Cerium,Helmholtz coil
更新于2025-09-10 09:29:36
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Role of oxygen vacancies in Co/Ni Substituted CeO2: A comparative study
摘要： Single phase Co/Ni substituted CeO2 nanoparticles reveal the importance of oxygen vacancies on the electronic properties of the materials. The effect of Co/Ni substitution on the structural, optical, and photoluminescence properties of CeO2 have been studied systematically. Lattice shrinks and hence strain increase owing to incorporation of Co/Ni in CeO2. Optical absorption analysis shows a red shift in band-gap with Co/Ni substitution. Photoluminescence studies reveals increase in defect concentration which causes quenching of PL emission. Vibration-modes at ~460 cm-1 in Raman spectra indicates incorporation of Co/Ni in CeO2 lattice whereas a broad peak appearing at ~ 540-640 cm-1 with substitution depicts the defects related to the increase in oxygen vacancy. X-ray absorption (XAS) studies show that Co/Ni substitution maintains local structure while Ce4+ → Ce3+ concentration increases to preserve the charge neutrality in lattice.
关键词： Oxygen vacancies.,Strain,Bandgap,Urbach energy,Cerium oxide
更新于2025-09-10 09:29:36