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Direct Amplification of High Energy Pulsed Laser in Fiber-Single Crystal Fiber with High Average Power
摘要： A laser master oscillator power ampli?er (MOPA) system consisting of a ?ber ampli?er and a two-stage Yb:YAG single crystal ?ber (SCF) is experimentally studied. The nonlinear stimulated Raman scattering (SRS) is avoided by limiting the output power of the ?ber preampli?er to 600 mW. Due to the bene?t from the low nonlinearity and high ampli?cation gain of the SCF, a laser pulse duration of 16.95 ps and a high average power of 41.7 W at a repetition rate of 250 kHz are obtained by using a two-stage polarization controlled double-pass ampli?cation of Yb:YAG SCF, corresponding to an output energy of 166.8 μJ and a peak power of 9.84 MW, respectively. The polarization controlled SCF ampli?cation scheme achieved a gain as high as more than 69 times. During the ampli?cation, the spectra gain narrowing e?ect and the polarization controlled four-pass ampli?cation setup are also studied. The laser spectrum is narrowed from over 10 nm to less than 3 nm, and the pulse width is also compressed to hundreds of femtosecond by dechirping the laser pulse. This compact-sized, cost-e?ective laser source can be used in laser micromachining, or as the seeder source for generating much higher power and energy laser for scienti?c research. For some applications which need femtosecond laser, this laser source can also be compressed to femtosecond regime.
关键词： ytterbium doped fiber amplifier,high-energy ultrashort laser amplification,single crystal fiber
更新于2025-11-28 14:23:57
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Investigation on the crack fracture mode and edge quality in laser dicing of glass-anisotropic silicon double-layer wafer
摘要： This work puts forward numerical and experimental investigations on laser dicing of glass-anisotropic single-crystal silicon double-layer wafer using laser induced thermal-crack propagation (LITP). A semiconductor continuous wave laser working at the defocusing mode serves as volumetric heat source for glass layer while as surface heat source for silicon layer. Based on the classical fracture theory, a static seam-type crack is introduced under the circumstance of ABAQUS to simulate the crack fracture modes in glass layer as well as silicon layer with crystal planes of (100), (110) and (111) during laser dicing in different dicing directions. In the experiments, processing parameters are kept the same as the simulations and typical dicing directions obtained from simulations are also used. The surface morphologies of crack edges are measured by the optical microscope and surface profiler. Through the comparison of numerical and experimental results it is discovered that for the specific substrate, the evolution of crack edge qualities in different dicing directions and different layers can be interpreted based on the corresponding stress distribution and stress intensity factor (SIF) ratio explicitly. And most important of all, the anisotropy of silicon layer has significant influence on the fracture mode and edge quality of crack in both layers.
关键词： Crack fracture mode,Laser induced thermal-crack propagation,Glass-anisotropic single-crystal silicon double-layer wafer,Crack edge quality,Static seam-type crack
更新于2025-11-21 11:24:58
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Bismuth vanadate single crystal particles modified with tungsten for efficient photoeletrochemical water oxidation
摘要： Highly efficient water oxidation utilizing visible light is a crucial step in water splitting. Bismuth vanadate (BiVO4) single crystal particles have attracted much attention in water oxidation recently, owing to their outstanding physicochemical properties and exposed active facets. The performance of BiVO4 single crystal particles is generally hindered by their poor conductivity and worse charge separation. Doping BiVO4 single crystal particles with other metal elements has been considered as an efficient way to improve their conductivity, charge separation and performance. However, there are few successful reports, because structure and morphology of BiVO4 single crystal particles are easily changed by addition of impurities. Here, we present that W doped BiVO4 crystal particles were successfully achieved by developing a simple impregnation method following with a high temperature annealing process. The obtained W-BiVO4 single crystal particles exhibited improved conductivity, carrier density and thereby enhanced activity for water oxidation. The solar energy conversion of the W-BiVO4 electrode was doubled compared with the pristine one. Thus, this work opens an avenue for developing efficient single crystal particle photocatalysts.
关键词： BiVO4,Tungsten,Single crystal particles,Water oxidation
更新于2025-11-19 16:51:07
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Single crystal structure and electroluminescence efficiency of blue fluorescence OLED emitters using triple core chromophores
摘要： The relationship between the single crystal structure of materials and the EL performance of doped OLED devices was investigated. The 1,6-bis-(10-[1,1′;3′,1″]terphenyl-5′-yl-anthracen-9- yl)-pyrene (1,6 DAP-TP) has a dihedral angle (α) of 78.4 ° and a dihedral angle (β) of 81.2 °, a relatively more twisted single crystal structure compared to that of 6,12-bis-(10- [1,1′;3′,1″]terphenyl-5′-yl-anthracen-9-yl)-chrysene (DAC-TP). Such a highly twisted molecular structure can improve the electroluminescence (EL) efficiency of a material because it can inhibit rotational and vibrational motions. Also, since the doped state and single crystal structure imply, respectively, a diluted state and a molecular state, the EL efficiency of the doped OLED device is related to single crystal structure. In a 4% doped OLED device, 1,6 DAP-TP and DAC- TP showed CE of 2.10 cd A-1 and 0.93 cd A-1, respectively. With its relatively more twisted single crystal structure, 1,6 DAP-TP showed higher CE in a doped OLED device than DAC-TP. Both compounds had ultra-deep blue emission y values of 0.06 or less for the color coordinates, which satisfy high density television display requirements (y value less than 0.08).
关键词： Organic light-emitting diode,single crystal,fluorescence,dopant,blue
更新于2025-10-22 19:40:53
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Perovskite CsPbBr3 single crystal detector for alpha-particle spectroscopy
摘要： Here we report the first spectroscopic alpha particle detection based on CsPbBr3 detectors with asymmetric contacts. The CsPbBr3 single crystal was grown from the melt using Bridgman method and then fabricated into detectors with different contacts. The In/CsPbBr3/Au detector presented a low dark current density (~100 nA/cm2) and temporal stable performance under high electric field (1000 V/cm). Such detector demonstrated excellent gamma ray resolving capability with a full-width at half maximum (FWHM) of ~5.9 keV for the 57Co 122 keV γ ray. The CsPbBr3 detector was capable of simultaneously resolving both the alpha particle (5.5 MeV) and γ ray (59.5 keV) peaks from 241Am radioactive isotope. The transport properties of CsPbBr3 were then determined based on the alpha particle spectra and corresponding rise time distributions. The equivalent values of electron and hole mobilities were indicated as 63 and 49 cm2/(V·s) respectively. The calculated electron and hole mobility-lifetime products were 4.5 × 10-4 and 9.5 × 10-4 cm2/V, respectively, demonstrating superior transport properties of holes over electrons in CsPbBr3. This work widens the scope of perovskite detectors to encompass charged radiation as well as high energy X/γ rays, and will significantly promote and guide further studies on perovskite materials for radiation detection applications.
关键词： CsPbBr3,Alpha particle detection,Crystal growth,Perovskite single crystal
更新于2025-09-23 15:23:52
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Growth and Optical Characterization of Europium and Cerium Doped KCl Single Crystals by Czochralski Method for Dosimetric Applications
摘要： Rare-earth-doped alkali halide single crystals KCl:Eu, KCl:Ce, and KCl:Eu,Ce were grown from melt using the Czochralski technique, and optical characterization was carried out with the prime focus on dosimetric applications. The grown crystals were investigated using XRD analysis, PL analysis, TSL measurements, and OSL measurements. The XRD of the crystals matched well with ICDD patterns (00-041-1476), and diffraction peaks can be assigned to the KCl structure, indicating that all the crystals have the same structure as KCl. The enhanced intensity of TSL and OSL was observed for co-doping of (Eu, Ce) in KCl crystals as compared to single doping. The appearance of a single glow peak in KCl:Eu,Ce at 230°C compared to single-doped KCl:Ce crystals suggested the use of the material in TL dosimetry. The intensity of OSL also showed a two-fold increase compared to single-doped crystals, suggesting its use in OSL dosimetry. PL studies showed a very high enhancement of intensity in Eu2+ emissions, reaching a maximum of about 421 nm in the (Eu2+, Ce3+) co-doped crystal compared to single-doped crystals. This justifies the occurrence of energy transfer from Ce3+ to Eu2+ in the KCl host lattice. These results showed that KCl:Eu,Ce acts as a potential TL and OSL dosimeter due to its high sensitivity to ionizing radiation.
关键词： crystal growth,Single crystal,potassium chloride,optical characterization,Czochralski method
更新于2025-09-23 15:23:52
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Extrinsic heavy metal atom effect on the solid state room temperature phosphorescence of cyclic triimidazole
摘要： Four coordination compounds [Zn3(CH3COO)6(H2O)2](TT)2, [Cd(H2O)6](ClO4)2(TT)2, [Cd(H2O)6](BF4)2(TT)2, [Zn(H2O)6](BF4)2(TT)2 (1-4) accommodating triimidazo[1,2-a:1',2'-c:1'',2''-e][1,3,5]triazine (TT) as a guest in their crystal lattice are isolated and fully photophysically and structurally characterized. Their emission properties are compared with those of afterglow TT and interpreted taking into account the heavy atom effect and crystal packing similarities and differences. In the case of 1, due to the closeness of the TT H-aggregates arrangement with that of the phosphor's pure phase, the observed intensification of the phosphorescent emission at the expense of the prompt one is attributed to the extrinsic heavy atom effect of Zn. In 2 and 3, the heavier Cd atom is responsible for a decrease in the lifetimes of the afterglow emission, despite the presence of tightly overlapped H-dimers in the crystal structure. Finally for 4, isostructural with 3, the Zn atom reveals in RTUP lifetime comparable with that of 1.
关键词： extrinsic heavy atom effect,H aggregates,time resolved photoluminescence,room temperature ultralong phosphorescence,single crystal XRD
更新于2025-09-23 15:23:52
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Single-Crystal ZnO/AlN Core/Shell Nanowires for Ultraviolet Emission and Dual-Color Ultraviolet Photodetection
摘要： Core–shell nanostructures can combine the advantages of different functional materials to realize property tunability and enhance optical and optoelectrical performance. Here, vertically aligned ZnO/AlN core/shell nanowires have been facilely fabricated by sputtering AlN layer onto the ZnO nanowires grown by vapor phase transport. The morphological and structural characterization reveals that single-crystal AlN shell layer with thickness of ≈15 nm is coated uniformly on the single-crystal ZnO nanowire with diameters of ≈330 nm. The core/shell nanowire exhibits 24 times enhancement of ultraviolet emission and quenching of the deep level emission from ZnO. Moreover, under ultraviolet irradiation (325 nm), the photodetector based on the core/shell nanowire displays higher photoresponsivity (from 3.8 × 103 to 2.05 × 104 A W?1), faster response speed (from 397 to 28 ms), and higher I325nm/Idark ratio (from 453 to 1.1 × 104) than that bare ZnO nanowire device. Under the vacuum ultraviolet (193 nm) illumination, the I193nm/Idark ratio and photoresponsivity are 300 and 381 A W?1, respectively. In one word, this paper employs a facile and general technique to solve a challenging fabrication issue, and obtains perfect crystal core/shell structure with high performance for ultraviolet emission and detection.
关键词： single-crystal core/shell,AlN,ZnO nanowires,ultraviolet emission,dual-color ultraviolet photodetection
更新于2025-09-23 15:23:52
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Electronic mobility and crystal structures of 2,5-dimethylanilinium triiodide and tin-based organic-inorganic hybrid compounds
摘要： We synthesize single crystals of a new 2,5-dimethylanilinium tin iodide organic-inorganic hybrid compound and 2,5-dimethylanilinium triiodide. Single-crystal X-ray diffraction reveals that the hybrid grows as a unique rhombohedral structure consisting of one-dimensional chains of SnI6-octahedra that share corners and edges to build up a ribbon along the [111] direction. Notably, we find that hypophosphorous acid, H3PO2, is of central importance to the formation of this hybrid. In the absence of H3PO2, we synthesize 2,5-dimethylanilinium triiodide from the same starting compounds. We investigate the synthesis routes that drive the growth of these two compounds with distinct crystal structures, appearance and properties. Pulse-radiolysis time-resolved microwave conductivity measurements and density functional theory calculations reveal that both compounds have low charge carrier mobilities and very long lifetimes, consistent with their one-dimensional structural characteristics. Our findings give a better understanding of the relation between synthesis, crystal structures and charge carrier mobilities.
关键词： Tin iodide,Single-crystal XRD,Organic-organic hybrids,Microwave conductivity,Hypophosphorous acid,Triiodide
更新于2025-09-23 15:23:52
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Single-Crystal Poly[4-(4,4-dihexadecyl-4H-cyclopenta[1,2-b:5,4-b′]dithiophen-2-yl)- <i>alt</i> -[1,2,5]thiadiazolo[3,4- <i>c</i> ]pyridine] Nanowires with Ultrahigh Mobility
摘要： We fabricated single-crystal poly[4-(4,4-dihexadecyl-4H-cyclopenta[1,2-b:5,4-b']-dithiophen-2-yl)-alt-[1,2,5]thiadiazolo-[3,4-c]pyridine] (PCDTPT) nanowires with ultrahigh mobility using a liquid-bridge-mediated nanotransfer molding method. The structural analysis of the single-crystal PCDTPT nanowires reveals that PCDTPT crystals have a triclinic structure, and the nanowires grow parallel to PCDTPT backbone chains, which provide important insights into its intrinsic charge transport. The single-crystal PCDTPT nanowire exhibits a superior charge carrier mobility of 72.94 ± 18.02 cm2 V-1 s-1 (maximum mobility up to 92.64 cm2 V-1 s-1), which is a record high value among conjugated polymers till date. In the single-crystal PCDTPT nanowire, the backbone chains in the linear structure along the nanowire growth axis lead to strong backbone delocalization, resulting in highly conductive polymer backbones and a drastic increase in charge carrier mobility. In addition, the single-crystal PCDTPT nanowire shows good environmental stability under air conditions compared to small-molecule organic semiconductors.
关键词： donor-acceptor-conjugated copolymers,liquid-bridge-mediated nanotransfer molding,PCDTPT,single-crystal polymer nanowire
更新于2025-09-23 15:23:52