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Tunable C-band and L-band multi-wavelength erbium-doped fiber ring laser based on a triple-core photonic crystal fiber with polarization-dependent loss
摘要： A tunable C-band and L-band multi-wavelength erbium-doped fiber laser (MW-EDFL) based on a novel fiber filter is proposed and experimentally demonstrated. The fiber filter is composed of a segment of triple-core photonic crystal fiber (TCPCF) and a segment of multi-mode fiber (MMF) between single mode fibers, which is inserted into the ring cavity of MW-EDFL as tuning component and wavelength selector. Based on the axial strain response of fiber filter, a tunable single-, dual- and triple-wavelength laser can be obtained with the tunable range of 19.58 nm, 10.34 nm, 6.84 nm, respectively. Meanwhile, the side-mode suppression ratio of lasing output is higher than 50 dB and the 3 dB linewidth is 0.026 nm for single wavelength lasing. Moreover, the lasing outputs are proved to be very stable at room temperature with the maximum wavelength shift of 0.06 nm and power fluctuation of 0.96 dB. Such a MW-EDFL with relatively simple structure and easy preparation has wide applications in important fields such as medicine, military, communication, and sensing.
关键词： In-line MZI,Tunable and switchable,Multi-wavelength erbium-doped fiber laser
更新于2025-09-23 15:21:01
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Structural, Morphological, and Optical Properties of Iron Doped WO3 Thin Film Prepared by Pulsed Laser Deposition
摘要： The iron doped tungsten-oxide (Fe and WO3) thin ?lm with di?erent morphology and crystalline structures were obtained for di?erent substrate temperatures at the oxygen pressure of 14.66 Pa. The Fe-doped WO3 ?lms were deposited by pulsed laser deposition (PLD). The in?uence of the substrate temperature on the surface and on the crystalline phases of the ?lms was studied. The XRD (X-ray di?raction) analysis indicates the changing in the crystalline phases from γ-monoclinic to a mixture of γ-monoclinic and hexagonal phases dependent on the temperature of annealing and as-grown ?lms. Related to the as-grown and annealing ?lms conditions, the SEM (scanning electron microscopy) shows a change in the image surface from nanoneedles, to nanoporous, and further to long nanowires and broad nanobands. Energy-dispersive X-ray spectroscopy (EDX) shows the elemental composition of the Fe-doped WO3 ?lm as-grown and after annealing treatment. Raman spectroscopy presented the main vibration mode of the Fe-doped WO3 thin ?lm. The optical energy bandgap of the ?lms is decreasing as the substrate temperature increases.
关键词： PLD method,tungsten trioxide,Fe-doped WO3,structural and morphological characterization
更新于2025-09-23 15:21:01
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Si-doping effect on solution-processed In-O thin-film transistors
摘要： In this work, silicon-doped indium oxide thin-film transistors (TFTs) have been fabricated for the first time by a solution processing method. By varying the Si concentration in the In2O3-SiO2 binary oxide structure up to 15 at.%, the thicknesses, densities, and crystallinity of the resulting In-Si-O (ISO) thin films were investigated by X-ray reflectivity (XRR) and X-ray diffraction techniques, while the produced TFTs were characterized by a conventional three-probe method. The results of XRR analysis revealed that the increase in the content of Si dopant increased the thickness of the produced film and reduced its density, and that all the Si-doped ISO thin films contained only a single amorphous phase even after annealing at temperatures as high as 800 °C. The manufactured ISO TFTs exhibited a reduction in the absolute value of threshold voltage VT close to 0 V and low current in the off-state, as compared to those of the non-doped indium oxide films, due to the reduced number of oxygen defects, which was consistent with the behavior of ISO TFTs fabricated by a sputtering method. The ISO TFT with a Si content of 3 at.% annealed at 400 °C demonstrated the smallest subthreshold swing of 0.5 V/dec, VT of ?5 V, mobility of 0.21 cm2/Vs, and on/off current ratio of about 2×107.
关键词： silicon-doped indium oxide,solution processing,amorphous oxide semiconductor,thin-film transistor,spin coating
更新于2025-09-23 15:21:01
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A study on structural, spectral, and magnetic properties of Pr–Bi co-doped M-type barium–strontium hexaferrites via the solid-state reaction method
摘要： Pr–Bi co-doped M-type Ba–Sr hexaferrites with nominal compositions Ba0.35Sr0.65?xPrxFe12.0?xBixO19 (0.00 ≤ x ≤ 0.40) were synthesized for the first time by the solid-state reaction method. These hexaferrites were characterized by X-ray diffractometer (XRD), Fourier transformer infrared (FT-IR) spectroscopy, field emission scanning electron microscopy (FE-SEM), vibrating sample magnetometer (VSM) and thermogravimetric analyzer (TGA). XRD patterns showed that the single M-type hexaferrite phase was obtained only if Pr–Bi content (x) ≤ 0.24. FT-IR frequency bands in the range (608–610) cm?1 and (445–447) cm?1 correspond to the formation of tetrahedral and octahedral clusters of metal oxides in the hexaferrites, respectively. FE-SEM micrographs indicated that the grains were of platelet-like shapes. The saturation magnetization (Ms), remanent magnetization (Mr), magnetic anisotropy field (Ha), first anisotropy constant (K1) and coercivity (Hc) first increased with Pr–Bi content (x) from 0.00 to 0.08, and then decreased when Pr–Bi content (x) ≥ 0.08. The Curie temperature (Tc) decreased with increasing Pr–Bi content (x) from 0.00 to 0.40.
关键词： Pr–Bi co-doped,structural properties,solid-state reaction method,spectral properties,magnetic properties,M-type barium–strontium hexaferrites
更新于2025-09-23 15:21:01
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Effects of lithium doping on: microstructure, morphology, nanomechanical properties and corrosion behaviour of ZnO thin films grown by spray pyrolysis technique
摘要： Li-doped ZnO thin films were prepared on glass substrate by a chemical spray pyrolysis method, in the temperature of 460 °C. The effects of Li content on the microstructural, morphological and mechanical characteristics of the doped (ZnO:Li) thin films were also examined. The XRD study showed a sharp preferred c-axis orientation and showed that (ZnO:Li) films have a würtzite structure and grow principally along the c-axis orientation with a preferred orientation (002). The film morphology was examined by (AFM) and (SEM). Results of SEM observations showed that sprayed thin films, exhibited uniform and harmonious texture. Furthermore, ZnO:Li thin films revealed uniform and spherical shaped crystallites with an approximate medium size of 200 nm. AFM characterization demonstrated an amelioration of the surface roughness of the ZnO:Li thin films. The mechanical characteristics of ZnO:Li thin films have been investigated by the nano-indentation experiment. It has been found that the addition of lithium enhances the hardness and Young’s modulus. On the other hand, the corrosion behaviour of Li-doped thin films is examined in chloride solutions. The electrochemical experiments confirmed that the lithium doping could ameliorate the anti-corrosion performance.
关键词： nanomechanical properties,morphology,microstructure,spray pyrolysis,thin films,Li-doped ZnO,corrosion behaviour
更新于2025-09-23 15:21:01
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Effect of the occupation of Ba and Ti sites on the structural, optical and dielectric properties of Sm-doped BaTiO3 ceramics
摘要： Sm-doped BaTiO3 powders have been synthesized with the help of the sol gel process. X-ray diffraction (XRD) patterns of the obtained powders, heat treated at a relatively low temperature (750 °C/3 h), revealed their crystallization in the pure perovskite structure without the presence of secondary phases. The occupation of the Ba and Ti sites by Sm in the BaTiO3 lattice and the evolution of the crystalline parameters as functions of the dopant content have been discussed based on XRD and Raman results. Dielectric measurements performed on the samples revealed a strong increasing diffuse character of the ferro-to-paraelectric phase transition with increasing Sm content. Moreover, the behavior of the permittivity as a function of frequency indicates that the samples are approaching their resonance frequency. The study of the conductivity showed the existence of a weak positive temperature coefficient of resistivity (PTCR) effect.
关键词： Sm-doped BaTiO3,dielectric properties,PTCR effect,perovskite structure,sol gel process
更新于2025-09-23 15:21:01
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Excellent structural, optical, and electrical properties of Nd-doped BaSnO <sub/>3</sub> transparent thin films
摘要： We epitaxially grew 7 mol. % Nd-doped BaSnO3 (NBSO) thin films on double-side polished SrTiO3 (001) single-crystal substrates and optimized the oxygen pressure (PO2), substrate temperature (TS), and film thickness (t) to achieve excellent structural, optical, and electrical performance. By keeping TS (?800 (cid:2)C) constant, NBSO films prepared at PO2 ? 10 Pa show the best crystallization, yielding a full-width at half-maximum (FWHM) of the x-ray diffraction rocking curve of 0.079(cid:2) and exhibiting a room-temperature resistivity (q) of (cid:3)1.85 mX cm and a volume carrier density (n) of (cid:3)8.5 (cid:4) 1020/cm3. By keeping PO2 (?10 Pa) constant, the room-temperature q of NBSO films could be reduced to as low as 0.5 mX cm by increasing TS from 700 to 825(cid:2); meanwhile, the volume carrier density and mobility show the maximum of 5.04 (cid:4) 1020/cm3 and 24.9 cm2/Vs, respectively, for TS ? 825 (cid:2)C. For all as-grown NBSO thin films, the optical transmittance in the visible wavelength region is larger than 80%. The optimized comprehensive properties of the NBSO films with FWHM ? 0.11(cid:2), q ? 0.5 mX cm, l ? 24.9 cm2/Vs, and T > 80% are superior to those of other rare-earth and 4d- and 5d-transition metal-doped BaSnO3 thin films.
关键词： optical properties,Nd-doped BaSnO3,electrical properties,transparent thin films,structural properties
更新于2025-09-23 15:21:01
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Adsorption for SO2 gas molecules on B, N, P and Al doped MoS2: the DFT study
摘要： In this paper, we investigated SO2 adsorption on B, N, P and Al doped MoS2, which band structure, density of states, charge transfer, etc by the density function theory (DFT) calculation. Results show that the SO2 prefer to be absorbed at the top of Mo atom of MoS2. It is found that SO2 is strongly adsorbed on Al-MoS2 with considerable adsorption energy of -1–-2.33eV, however, the best adsorption position is the top of Mo atom of Al-MoS2, which the biggest Ea is -2.33eV, the best charge is -0.343e and the shortest d is 1.763?. So these findings confirm that Al-MoS2 can be used to detect the presence of SO2 in the environment.
关键词： SO2 adsorption,MoS2,Al-MoS2,doped MoS2,DFT study
更新于2025-09-23 15:21:01
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Facile Preparation of Highly Luminescent Nitrogen-Doped Carbonaceous Nanospheres and Potential Application in Intracellular Imaging of Quercetin
摘要： Highly luminescent nitrogen-doped carbonaceous nanospheres (LNCNs) were synthesized by a one-pot hydrothermal reaction of b-cyclodextrin (b-CD) and branched polyethylenimine (BPEI). Both the N-doping and amino-functionalisation of LNCNs were achieved simultaneously. The prepared LNCNs display excellent properties such as high physical and chemical stability, excitation wavelength-independent emission, and high photoluminescence quantum yields. Importantly, the LNCNs exhibit a quenching of photoluminescence in the presence of quercetin (Qc) based on the simple static quenching mechanism, making it possible to quantify concentrations from 0.5 to 80 mg mL(cid:1)1 with a detection limit of 0.21 mg mL(cid:1)1. Furthermore, the LNCNs probe was further used for imaging Qc in living cells.
关键词： quercetin,photoluminescence quenching,nitrogen-doped carbonaceous nanospheres,intracellular imaging
更新于2025-09-23 15:21:01
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Nanoscale charge transport and local surface potential distribution to probe defect passivation in Ag doped Cu2ZnSnS4 absorbing layer
摘要： The performance of earth abundant Cu2ZnSnS4 (CZTS) material is limited by high deficit of open circuit voltage (VOC) which is mainly due to the easy formation of CuZn antisite defects. Suppression of CuZn defects is thus inevitably required for further developments in CZTS based solar cells. We studied systematic increase of Ag doping in CZTS thin film and investigated the nanoscale electrical properties using kelvin probe force microscopy (KPFM) and current sensing atomic force microscopy (CAFM) to probe CuZn defects. Crystallographic analysis indicated the successful partial substitution of Cu+ ions by large size Ag+ ions. The considerable decrease in grain boundary potential from 66.50 ± 5.44 mV to 13.50 ± 2.61 mV with Ag doping, suggesting the substantial decrease in CuZn defects. Consequently, CAFM measurement confirms the remarkable increment in minority carrier current with Ag doping and their local mobility in CZTS layer. Finally, the lower persistent photoconductivity (PPC) and fast decay response of photogenerated carriers for Ag doped CZTS photodetector further validate our results. This study provides a fresh approach of controlling deleterious CuZn defects in CZTS by tuning Ag content that may guide researchers to develop next generation high performance CZTS based solar cells.
关键词： nanoscale surface potential and current,CZTS solar cells,Ag doped CZTS,defects,photodetector
更新于2025-09-23 15:21:01