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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Improvement of soliton pulse energy in thulium-doped fiber laser
摘要： In this paper, we report a thulium-doped fiber laser based on non-polarization rotation technique. Increasing the pump power to 2500 mW and adjusting the polarization controllers, Baussian pulse with high pulse energy can be achieved. The pulse duration of de-chirped pulse is 242 fs. Due to dispersion management, most related studies are still focused on the 1 μm band, and few reports are available for the 2 μm band. By using non-polarization rotation technique, the mode-locked start-up threshold can be avoided. At the maximum pump power, the direct output power of the resonator cavity is 272.2 mW, and the corresponding single pulse energy is 1.825 nJ.
关键词： mode-locking,thulium-doped fiber laser,non-polarization rotation technique,dispersion management
更新于2025-09-16 10:30:52
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Fabrication of Carbon-decorated Al<sub>2</sub>O<sub>3</sub> Composite Powders using Cellulose Nanofiber for Selective Laser Sintering
摘要： In this study, systematic investigation using cellulose nanofiber (CellNF) as a carbon source for selective laser sintering (SLS) of Al2O3 was conducted. A composite powder that consisted of CellNF and Al2O3 was fabricated using electrostatic adsorption (EA) method in aqueous suspension. Heat-treatment temperature of 500 and 800°C was compared for the conversion of CellNF to carbon residue (CR) in the Al2O3 composite. After that, the parameters involving the volume fraction of CR and effect of Al2O3 particle size in the CR-Al2O3 composite particle were also investigated in order to obtain an optimized condition of the CR-Al2O3 composite particle for SLS. From the results obtained, 1.5 wt% CR-Al2O3 with alumina size of 0.8 μm that was heat-treated at 800°C exhibited optimum laser sinter ability owing to the good CR distribution over a higher surface area that promoted good laser adsorption for the alumina sintering.
关键词： additive manufacturing,nano-assembly technique,selective laser sintering,cellulose nanofiber,electrostatic adsorption
更新于2025-09-16 10:30:52
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Radiation Characteristics of Two Semi-Infinite Overlapped Cylindrical Waveguides with Impedance Loading
摘要： The radiation of plane waves by two coaxial overlapping pipes is investigated in the case where the walls of the pipes lying in the overlap region are impedance boundaries. By using the eigenfunction expansion in the overlap region and using the Fourier transform technique elsewhere we obtain directly two uncoupled modified Wiener-Hopf equations of the second kind whose solutions involve two set of infinitely many unknown expansion coefficients satisfying two systems of linear algebraic equations. Numerical solution of these systems are obtained for various values of the parameters of the problem whereby are studied the effects of these parameters on the radiation phenomenon.
关键词： Wiener-Hopf technique,cylindrical waveguides,radiation,impedance loading
更新于2025-09-16 10:30:52
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Magnetic field to focalize and accelerate ions produced by ns laser-generated plasmas
摘要： Solid targets have been irradiated in vacuum by an ns-laser pulse producing non-equilibrium plasma accelerating ions along the normal to the target surface. The ions emission can be focused by cylindrical permanent magnets in order to enhance the ion current. The electron traps formation along the main emission direction produces an electrical field driving further ion acceleration. Measurements using time-of-flight technique have been developed to quantize the focusing and accelerating effects induced by the applied magnetic field. Experimental measurements were compared with theoretical calculations obtained using COMSOL software, as it will be presented and discussed.
关键词： ion acceleration,time-of-flight technique,Magnetic field,laser-generated plasmas,COMSOL software
更新于2025-09-16 10:30:52
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Laser-induced forward transfer of silver nanoparticle ink using burst technique
摘要： Laser-induced forward transfer (LIFT) is an effective approach to print materials in liquid state with high resolution. This procedure, however, suffers from bulging problem when printing continuous lines or patterns. In this study, LIFT of silver nanoparticle ink using burst technique was developed to mitigate this issue during printing continuous lines. Firstly, a set of droplet printing experiments were conducted to investigate the influences of the pulse energy and burst mode on the morphologies of the printed features. It was found that the resolution was enhanced and the phenomenon of splashing was improved with the introduction of burst technique at the same energy level. Thereafter, a group of lines were printed by changing the scanning speed in bursts of 1, 2 or 3 pulses. The results showed that the bulging of the printed line was effectively mitigated and the resolution was significantly improved in burst-3 mode.
关键词： Continuous lines,Laser-induced forward transfer,Burst technique,Silver nanoparticle ink,Printing
更新于2025-09-16 10:30:52
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The Analysis and Improvement of the Influence Factors for the Fabrication of SMT Template and Laser Cutting Technique
摘要： This paper briefly introduces the fabrication of SMT template and laser cutting technique, analyzes the factors that influence the SMT template fabrication and the laser cutting quality. Then it studies the improvement measures and methods through practical applications.
关键词： Laser Cutting,Cutting Technique Improvement,SMT,SMT Printing Template
更新于2025-09-16 10:30:52
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Thermo-mechanical analysis of blister formation on a rigid substrate in blister-actuated laser-induced forward transfer
摘要： The paper presents an analytic model of glass-interface-polyimide structure for predicting the blister formation during blister-actuated laser-induced forward transfer. In order to investigate the dynamic process of the heating and vaporizing of polymer in laser/matter interaction and crack propagation of glass/polymer interface in blister expansion, a discrete quasi-static analysis method is proposed. In the frame of fracture mechanics, the energy release rate is calculated and introduced to analyze interfacial crack propagation of glass/polymer interface. In additional, the blister expansion and formation are also computed based on a finite element model, and the analytical predictions are shown to be in good agreement with simulated results. The results show that blister height and crack length are sensitive to laser fluence. A higher laser fluence is much easier to induce higher blister height. The crack will propagate as the laser fluence is larger than the critical laser fluence.
关键词： polymer,blister formation,virtual crack closure technique,blister-actuated laser-induced forward transfer,crack propagation
更新于2025-09-16 10:30:52
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Standards, Methods and Solutions of Metrology || Third-Order Nonlinear Optical Properties of Quantum Dots
摘要： Quantum dots (QDs) are semiconducting nanocrystalline particles. QDs are attractive photonic media. In this chapter, we introduce third-order nonlinear optical properties and a brief idea about the physics of QDs. Z-scan technique and theoretical analysis adopted to obtain nonlinear parameters will be discussed. Analysis of third-order nonlinear optical parameters for PbS QDs suspended in toluene with radii 2.4 and 5.0 nm under different excitation beam power level and three different wavelengths (488, 514, and 633 nm) will be detailed. Third-order optical susceptibility χ(3) and optical-limiting behavior of PbS QD suspended in toluene are presented. Irrespective of their size, QDs are a good example of optical limiters with low threshold.
关键词： Z-scan technique,semiconductor,nonlinear absorption coefficient,third-order optical susceptibility,quantum dot,optical limiting,nonlinear optics,optical switching,nonlinear index of refraction
更新于2025-09-16 10:30:52
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Defect Imaging from a Remote Distance by Using Scanning Laser Source Technique with Acoustic Microphones
摘要： Images of defects in plate-like structures can be generated using the scanning laser source (SLS) technique. When a laser Doppler vibrometer (LDV) is used as a receiving device in the SLS technique, images of defects can be obtained through measurements conducted from a distance. Because an LDV cannot receive vibrations reflected from outdoor structures that may have rough surfaces and large fluctuations in a stable manner, this paper discusses an imaging technique using a SLS with acoustic microphones as a receiving device. The results of the experiments that were conducted using various distances between the test plate and microphone showed that the quality of the defect images gradually degraded because of the attenuation of sound in air as the distance increased. Moreover, when the laser beam was reflected back to the microphone after scattering over the plate surface, the laser beam directly generated signals in the microphone due to the photovoltaic effect or alternating heat, preventing the acquisition of defect images. Thereafter, in order to establish remote defect imaging, an acoustic transmitter was connected to the microphone unit. Most of the experimental equipment were located at a remote distance except for the small microphone unit and transmitter. The experimental system enabled the generation of images of the defect in the test plate located at distances of 4 and 6 m.
关键词： non-destructive testing,acoustic transmitter,scanning laser source technique,microphone
更新于2025-09-16 10:30:52
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Synthesis of Cu <sub/>2</sub> ZnSnSe <sub/>4</sub> from nitrate and selenite inks for use as an absorbent layer in the design of solar cells
摘要： This research was conducted to identify two acceptable precursors and methods of synthesis for the manufacture of photovoltaic cells. The kesterite Cu2ZnSnSe4, a promising material for solar cell applications, was synthesized from metal salts of Cu, Zn, Sn, and Se, by two low-cost routes: the direct dissolution of metal nitrates, and coprecipitation of selenites. In both cases, inks were obtained and deposited as thin-films by the Doctor Blade technique on glass substrates coated with molybdenum. The films were annealed in an oven at 550°C by 30 minutes. The phases of each thin film were analyzed by X-ray diffraction and Raman scattering. The morphology and the thickness of the layers were observed using a scanning electron microscope. The optical band gap was determined by ultraviolet-visible spectroscopy and the Tauc equation. The results confirmed the main phase of kesterite material, consistent with a tetragonal crystalline system oriented along the plane (1 1 2). These values are consistent with those found by Raman spectroscopy, where the main vibrational mode was identified at 173 cm-1 and 196 cm-1, characteristic of mode A vibration, and 243 cm-1 of mode B vibration; typical of kesterite. Simultaneously, a band gap of 0.89 eV was identified. These results demonstrate the effectiveness of the selenite′s coprecipitation method for synthesis of kesterite, without evidence of secondary phases. This determines the possibility of using this material in solar cell applications.
关键词： solar cells,Cu2ZnSnSe4,selenite coprecipitation,Doctor Blade technique,kesterite
更新于2025-09-16 10:30:52