修车大队一品楼qm论坛51一品茶楼论坛,栖凤楼品茶全国楼凤app软件 ,栖凤阁全国论坛入口,广州百花丛bhc论坛杭州百花坊妃子阁

oe1(光电查) - 科学论文

过滤筛选

出版时间
  • 2019
研究主题
  • Digital signal processing techniques for optical communications
  • transmission impairments and their mitigations
  • multiplexing and demultiplexing techniques including OTDM
  • OFDM
  • OCDM and SDM
应用领域
  • Optoelectronic Information Science and Engineering
机构单位
  • Beijing Electronic Science and Technology Institute
860 条数据
?? 中文（中国） ▾

  • Microstructure and properties of high strength and high conductivity Cu-Cr alloy components fabricated by high power selective laser melting

    摘要： Although different kinds of metal materials have been built in the past years, it is difficult to fabricate the components of copper alloys with high strength and high conductivity due to their high reflectivity and thermal conductivity. In this paper, Cu-Cr alloy with high strength and high conductivity was successfully manufactured by high laser power selective laser melting. The microstructure, mechanical properties and conductivity were studied and compared before and after the heat treatment. The microstructure of the as-built sample was columnar grains with very fine cellular sub-structures and precipitates of Cr and Cr2O3. After heat treatment, the Cr particles precipitated from Cu matrix, resulting in simultaneous increase in strength and conductivity. The ultimate tensile strength of 468 MPa, yield strength of 377.33 MPa, and electrical conductivity of 98.31% IACS were achieved, which is even better than the samples fabricated by rolling with post heat treatment.

    关键词： Cu-Cr alloy,Electronic conductivity,Laser processing,Microstructure,Mechanical properties

    更新于2025-11-28 14:24:20

  • [Communications in Computer and Information Science] Data Mining Volume 996 (16th Australasian Conference, AusDM 2018, Bahrurst, NSW, Australia, November 28–30, 2018, Revised Selected Papers) || Effect of Nickel Foil Thickness on Microstructure and Microhardness of Steel/Aluminium Alloy Dissimilar Laser Welding Joints

    摘要： Laser lap welding between DP980 steel and 6061 aluminum alloy was carried out using IPG YLS-6000 fiber laser, nickel foil with different thickness (0.10, 0.20 and 0.30 mm) was used as interlayer. The microstructure was observed by SEM, EDS was used to determine the distribution of elements and intermetallic compounds types, and the hardness was determined by HV1000IS. The results showed that the microstructure in weld seam (WS) and fusion line (FL) of welded joint without nickel foil was d ferrite and lath martensite (LM). For welded joints with nickel interlayer, the d ! c phase transition was promoted by nickel elements. Thus, with the thickness of the nickel foil increased, the content of nickel elements in weld pool increased, resulting in decrease of d ferrite content in WS and FL. Meanwhile, the microstructure in WS and FL was full LM when the thickness of the nickel foil was 0.30 mm. Meanwhile, the NixAly IMC was found in interface, which inhibited Fe–Al metallurgical reaction and reduced the thickness of Fe–Al IMC. Therefore, with nickel foil thickness increased, the content of nickel elements and the NixAly IMC increased. Moreover, the maximum thickness of the IMC layer was able to reduce to 10.66 when the thickness of the nickel foil was 0.10 mm. With the reduction of d ferrite content in WS and FL, the microhardness in WS increased with the thickness of the nickel foil increased. However, because the NixAly IMC was a soft phase, the microhardness in interface decreased, significantly.

    关键词： Steel,Processing,Aluminum,Laser welding

    更新于2025-11-28 14:24:20

  • Effect of pre-existing nuclei on crystallization during laser welding of Zr-based metallic glass

    摘要： In this study, experiments are carried out in laser welding of a Zr-based (Zr52.5Ti5Al10Ni14Cu17.9) bulk metallic glass (BMG), pre-existing nuclei nucleus density has significant influence on its crystallization behavior. Based on the classical nucleation/growth theory, it is concluded that a small amount of pre-existing nuclei in a BMG can shift the time-temperature-transformation (TTT) curve from a well-known ‘C-shape’ to a ‘ε-shape.’ This result provides fundamental understanding on why the shape of the TTT curve for a heating process is different from that for a cooling process for the same BMG. Two quality factors were defined as a measure of the effect of pre-existing nucleus density. By integrating the classical nucleation/growth theory with the heat transfer model, the evolution of crystalline phase during laser welding for a BMG with pre-existing nuclei was studied, and the modeling predictions compared favorably with the experimental results.

    关键词： Crystallization,Nucleation and growth,Laser processing,Metallic glasses,Amorphous alloys

    更新于2025-11-28 14:24:20

  • Tailoring Properties of Microcavity In-line Mach-Zehnder Interferometer by the Microcavity Enlargement using Femtosecond Laser

    摘要： This work presents a theoretical analysis and experimental verification of fine-tuning of the spectral response and refractive index (RI) sensitivity of microcavity in-line Mach-Zehnder interferometer (μIMZI). The μIMZIs were fabricated using femtosecond (fs) laser micromachining in standard single-mode fibers as circular cavities with a diameter of 60 μm. Next, the structures underwent fs laser post-processing, which included fabrication of an additional cavity with the same diameter but shifted by 15 μm or 30 μm against the center of the initial microcavity. Different depths of the additional structures were investigated. The enlargement of the microcavity allows for tailoring the spectral response, i.e., it shifts the interference pattern by more than 200 nm, with no introduction of any additional losses and distortions in the spectrum. As the additional effect, regardless of the size of the extension, the sensitivity of the enlarged μIMZI was improved by 32%.

    关键词： Fiber optics sensors,Laser materials processing,Interferometry,Microcavities,Microstructure fabrication

    更新于2025-11-28 14:23:57

  • Enhanced optical Kerr nonlinearity of graphene/Si hybrid waveguide

    摘要： In this work, we experimentally study the optical Kerr nonlinearities of graphene/Si hybrid waveguides with enhanced self-phase modulation. In the case of CMOS compatible materials for nonlinear optical signal processing, Si and silicon nitride waveguides have been extensively investigated over the past decade. However, Si waveguides exhibit strong two-photon absorption (TPA) at telecommunication wavelengths, which leads to a signi?cant reduction of the nonlinear ?gure-of-merit (FOM). In contrast, a silicon nitride based material system usually suppresses the TPA but simultaneously leads to the reduction of Kerr nonlinearity by one order of magnitude. Here, we introduce a graphene/Si hybrid waveguide, which maintains the optical properties and CMOS compatibility of Si waveguides, while enhancing the Kerr nonlinearity, by transferring over to the top of the waveguides. The graphene/Si waveguides are measured to have an enhanced nonlinear parameter of 510 W(cid:2)1 m(cid:2)1, compared with that of the Si waveguide of 150 W(cid:2)1 m(cid:2)1. An enhanced nonlinear FOM of 2.48 6 0.25 has been achieved, which is four times larger than that of the Si waveguide of 0.6 6 0.1. This work reveals the potential application of graphene/Si hybrid waveguides with high Kerr nonlinearity and FOM for nonlinear all-optical signal processing.

    关键词： nonlinear all-optical signal processing,graphene/Si hybrid waveguide,optical Kerr nonlinearity,CMOS compatible,self-phase modulation

    更新于2025-11-28 14:23:57

  • Effects of Platform Pre-Heating and Thermal-Treatment Strategies on Properties of AlSi10Mg Alloy Processed by Selective Laser Melting

    摘要： The AlSi10Mg alloy was processed by selective laser melting using both hot- and cold-build platforms. The investigation was aimed at defining suitable platform pre-heating and post-process thermal treatment strategies, taking into consideration the peculiar microstructures generated. Microstructural analyses, differential scanning calorimetry, and high-resolution diffraction from synchrotron radiation, showed that in the cold platform as-built condition, the amount of supersaturated Si was higher than in hot platform samples. The best hardness and tensile performance were achieved upon direct aging from cold platform-printed alloys. The hot platform strategy led to a loss in the aging response, since the long processing times spent at high temperature induced a substantial overaging effect, already in the as-built samples. Finally, the standard T6 temper consisting of post-process solution annealing followed by artificial aging, resulted in higher ductility but lower mechanical strength.

    关键词： processing temperature,AlSi10Mg alloy,aging treatment,selective laser melting

    更新于2025-11-21 11:18:25

  • Effect of thermal stress induced by femtosecond laser on fracture toughness of fine-grained alumina

    摘要： The ultra-sharp V-notch with tip radius smaller than 0.5 μm was cut by femtosecond laser on the fine-grained alumina ceramic bars to measure the fracture toughness by single-edge V-notched beam (SEVNB) method. In order to relieve the effect of thermal stresses induced by laser on fracture toughness testing, the samples with V-notch were annealed before measurement. The morphologies of the notch tip were analyzed by SEM and micro-Raman spectra. Results reveal that the fracture toughness value of this fine-grained alumina with thermal stresses on the V-notch is equal to that after annealing, and the effect of thermal stresses induced by laser on the fracture toughness can be ignored.

    关键词： SEVNB,Fracture toughness,Laser processing,Thermal stress,Alumina

    更新于2025-11-21 11:18:25

  • Tailored focal beam shaping and its application in laser material processing

    摘要： Besides the optimization of the laser and processing parameters, the adaptation of the focal intensity distribution offers great potential for a well-defined control of laser processing and for improving the processing results. In this paper, different tailored intensity distributions were discussed with respect to their suitability for femtosecond laser material processing on the micro- and nanoscale such as cutting, marking, and the generation of laser-induced periodic surface structures. It was shown by means of laser processing of stainless steel that the numerical simulations for the beam shaping unit are in good agreement with the experimental results. Also, the suitability of the beam shaping device to work with a scanner and an F-theta lens as commonly used for material processing was demonstrated. In this context, the improvement of the machining results was shown experimentally, and a significant reduction of the machining time was achieved.

    关键词： laser-induced periodic surface structures,donut,femtosecond laser processing,top-hat,beam shaping

    更新于2025-11-21 11:01:37

  • Spectral analysis and temperature measurement during flash sintering under AC electric field

    摘要： In-situ diffraction experiments were used to study the change in peak profiles of 8YSZ during conventional sintering and flash sintering under AC electric field. Using calibration from a conventionally heated standard, the lattice expansion of 8YSZ under flash conditions was correlated to actual specimen temperature, indicating temperature comparable to that required for conventional sintering. At higher current densities, a temperature rise greater than 2000 °C was reached, which resulted in abnormal grain growth and temperature instability. Microstructural analysis demonstrated that finer grain size can be achieved by limiting the current in order to avoid high specimen temperatures. Experiments varying the thickness of the green compact resulted in higher heat loss due to thermal conduction and corresponding reduction in final density. A replacement to the blackbody radiation model was successfully used to fit the data and explain all effects based on Joule heating as well as provide a flash sintering processing map incorporating furnace temperature, power dissipation, and sample geometry.

    关键词： 8YSZ,processing map,fast firing,flash sintering,energy dispersive diffraction

    更新于2025-11-21 11:01:37

  • Crosslink network and phenyl content on the optical, hardness, and thermal aging of PDMS LED encapsulant

    摘要： This work aims to synthesize new series of polysiloxane copolymer through hydrosilylation reaction based on different level of crosslink densities and phenyl content. The results revealed that polysiloxanes resins with phenyl rings increased viscosity up to 3800 cps while displaying a relatively high refractive index of 1.531. The asymmetric phenyl substitution onto chain backbone led to formation of densely packed structure resulting in reduced water absorption and gas permeability of PDMS resins. High level of crosslinking contributed to a high shore A hardness and adhesion strength. It displayed transparency of 97% whose percentage reduction was 1.6% under thermal and 0.6% UV aging. No obvious discoloration was observed during accelerated thermal aging up to 210 min at 80 (cid:1)C. These results are key attributes that make the synthesized polysiloxane series as ideal candidate for high brightness LED encapsulant. ? 2019 Wiley Periodicals, Inc. ? 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47895.

    关键词： copolymers,thermal properties,ring-opening polymerization,optical properties,synthesis and processing techniques

    更新于2025-11-19 16:56:42