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Wavelength and sensitivity tunable long period gratings fabricated in fluid-cladding microfibers

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Chinese Physics B 2022年第1期31卷 299-304页

作者： Wa Jin Linke Zhang Xiang Zhang Ming Xu Weihong Bi yuefeng qi Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province Qin Huangdao 066004China School of Information Science and Engineering Yanshan UniversityQin Huangdao 066004China

We report the fabrication of long period gratings in fluid-cladding microfibers by directly focusing a femtosecond laser beam on the microfibers surface to induce periodical modification a long one side of the microfibers.A long period grating is fabricated in a water-cladding microfiber with a diameter of~5μm,which demonstrates a resonant attenuation of 28.53 dB at wavelength of 1588.1 nm with 10 *** water cladding is changed to be refractive index oil of n=1.33 and alcohol solution with concentration of 5%,the resonance wavelength shifts to 1575.1 nm with resonant attenuation of 24.91 dB and 1594.1 nm with resonant attenuation of 35.9 dB,*** long period grating demonstrates different temperature sensitivities of-0.524 nm/℃,-0.767 nm/℃and-1.316 nm/℃for water,alcohol solution and refractive index oil cladding microfibers,respectively,which means the alterable liquid cladding allows the availability of tunable wavelength and *** fluid-cladding protects the microfibers from external disturbance and contamination and allows more flexibility in controlling the transmission property and sensing characteristics of long period gratings,which can be used as fiber devices and sensors for chemical,biological,and environmental applications.

关键词： fluid-cladding microfiber long-period grating temperature

Long dynamic range spread spectrum optical domain reflectometer

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Optoelectronics Letters 2021年第11期17卷 651-655页

作者： ZHANG Fang ZHANG Hongling qi yuefeng LI Wei School of Information Science and Engineering Yanshan UniversityQinhuangdao 066004China Department of Information Engineering Hebei University of Environmental EngineeringQinhuangdao 066102China School of Electric Engineering Hebei University of ArchitectureZhangjiakou 075000China China Electronics Engineering Design Institute Co. Ltd.Beijing 100142China

The performance of an optical time domain reflectometer(OTDR) is significantly improved using spread spectrum technology. The concept of spread spectrum OTDR(SSOTDR) is proposed, the theoretical basis and simulation results of the new method are given, and the problem of direct application of bipolar spread spectrum codes to OTDR and despreading in the optical domain are solved. The simulation results show the feasibility of the SSOTDR, which exhibits better dynamic range reported to date for a practical long-haul OTDR system without using conventional average technique.

关键词： simulation domain Long dynamic range spread spectrum optical domain reflectometer

Research on Michelson interference refractive index sensing technique based on double-core microfiber

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Optoelectronics Letters 2021年第9期17卷 513-517页

作者： ZHANG Hongling ZHANG Fang CONG Bitong qi yuefeng School of Information Science and Engineering Yanshan UniversityQinhuangdao 066004China Zhangjiakou Key Laboratory for Intelligent Architecture Hebei University of ArchitectureZhangjiakou 075000China Department of Information Engineering Hebei University of Environmental EngineeringQinhuangdao 066004China

We propose a novel refractive index sensor based on Michelson interferometer by using double-core *** the reflection of the end and taper of double-core fiber(DCF),the Michelson interference spectrum is *** to the structure characteristic of double-core microfiber,this interferometer can achieve the measurement of refractive index(RI)and *** experimental results show that the refractive index sensitivity of the interferometer is 2377.80 nm/RIU at the diameter of the taper waist of 8.76μ*** the temperature ranges from 30°C to 60°C,the temperature sensitivity is 0.07048 nm/°*** sensor has the advantage of high refractive index sensitivity.

关键词： interferometer Michelson temperature

Microstructure and mechanical properties of AlSiCu10-10 filler meter brazing 6063 aluminum alloy

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China Welding 2018年第4期27卷 52-56页

作者： Chen Yilan qi yuefeng Liu Xu Beijing Non-ferrous Metals and Rare Earth Research Institute Beijing 100012 China

AlSiCu_(10-10) flame brazing 6063 aluminum alloy was rearched,and microstructure and mechanical properties of brazed joints were tested in the experiments. The interfacial microstructures and brazing phases of brazed joints were analyzed by scanning electron microscopy( SEM) and X-ray energy dispersive spectroscopy( EDS). The strength of brazed joints was aquired by tensile test. The results show that the AlCu_2 and Mg_2 Si phases were formed in the brazing seam,the former is the brittle phase,the Mg_2 Si phases is considered to be the strengthening phase of the aluminum alloy,which can reduce the brittleness caused by AlCu_2. The average tensile strength of brazed butt joint was 115 MPa,and the average shear strength of brazed joint was 26 MPa. Finally,the fracture form and fracture morphology of the brazed joint were analyzed.

关键词： aluminum silicon copper brazing microstructure mechanical properties

Joining of activated graphite to 6063 aluminum alloy with Al-Cu-Si-Ni-Mg filler metal

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China Welding 2020年第4期29卷 60-64页

作者： Yuan Linlin Huang Xiaomeng Chen Xiaoyu qi yuefeng Beijing Non-ferrous Metals and Rare Earth Research Institute Beijing 100012China Beijing Engineering Research Center of New Brazing Materials for Electronic Information Beijing 100012China

In this work, 6063 aluminum alloy-graphite joint intended for thermal conductive application were realized by applying Al-CuSi-Ni-Mg brazing filler metal and Ag-Cu-Ti pasted on high density graphite substrate to ensure wetting during the brazing process. The interface reactions during brazing and mechanical properties were studied using scanning electron microscopy(SEM) and shear test *** was formed at the graphite/active Ag-Cu-Ti paste interface due to the reaction between Ti and C, and thus the wettability on the graphite was *** is shown that joint with a good quality can be produced at a brazing temperature of 550 ℃ for 10 *** average tensile strength of the joint is 21 MPa. thus the wettability on the graphite was *** is shown that joint with a good quality can be produced at a brazing temperature of 550 ℃ for 10 min.

关键词： graphite aluminum alloy metallization reactive brazing

Novel Fiber Optic Current Transformer With New Phase Modulation Method

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Photonic Sensors 2020年第3期10卷 275-282页

作者： yuefeng qi Mingjun WANG Fengxian JIANG Xin ZHANG Bitong CONG Yanyan LIU School of Information Science and Engineering Yanshan UniversityQinhuangdao 066004China The Key Laboratory for Special Fiber and Fiber Sensor of Hebei Province Qinhuangdao 066004China Li Ren College of Yanshan University Qinhuangdao 066004China

Based on the transverse electro-optic effect of lithium niobate crystal,combined with polarizers and Faraday rotator,this paper presents a collinear closed-loop fiber optic current transformer with spatial non-reciprocity modulation method,and the feasibility of the scheme is verified by both the theoretical and experimental *** detection scheme avoids the limitation of the transition time of the sensing fiber coil on the phase modulation frequency,improves the sensitivity and stability of the system,and reduces the volume and cost of fiber optic current *** sawtooth wave modulation scheme is adopted to realize phase bias modulation and feedback modulation through phase shift of sawtooth wave to achieve closed-loop detection effect,which enhances the signal to noise ratio and simplifies demodulation *** experimental results show that the current ratio errors measured at room temperature range from 1%to 120%of rated current meet the requirements of national standard GB/T 20840.8-2007 and reach the accuracy level of *** temperature stability of the current transformer is also tested,and the ratio error measured at the rated current does not exceed±0.2%in the range of-30℃to 50℃.

关键词： Fiber optic current transformer spatial phase modulation closed-loop detection current ratio error temperature stability

Brazing of 5A01 aluminum alloy using Al-Cu-Si-Ni filler metal

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China Welding 2018年第4期27卷 41-45页

作者： Yuan Linlin Shi Xiumei Liu Xu qi yuefeng Huang Xiaomeng Non-ferrous Metals and Rare Earth Research Institute Beijing Beijing Engineering Research Center of New Brazing Materials for Electronic Information

The vacuum brazing of 5 A01 aluminum alloy using Al-Cu-Si-Ni filler metal was investigated at 550 ℃ and 560 ℃,respectively. Microstructure and properties of brazed 5 A01 alloy joints were investigated by tensile-shear tests and scanning electron microscopy analysis. The effects of brazing temperature and holding time on the shear strength and microstructure of the joints were studied. The results show that the different intermetallic compounds such as Al-Cu-Ni and Mg_2 Si formed in the bonding area. Shear strength increased with holding time and brazing temperature. The average shear strengths increased from 42. 3 MPa brazed at 550 ℃for 5 min to 68 MPa brazed at 560 ℃ for 15 min. Discontinuous cracks were found in the joint brazed at 550 ℃ for 5 min,and the joint showed poor shear strength. high shear strength were obtained in the joints brazed at 560 ℃ for 15 min.

关键词： aluminum brazing microstructure mechanical properties

Performance analysis of 5A05 alloy brazed in vacuum with AlCuAg series filler metal

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China Welding 2020年第3期29卷 59-64页

作者： Huang Xiaomeng qi yuefeng Zhang Guoqing Liu Xu Chen Xiaoyu Beijing Non-ferrous Metal and Rare Earth Research Institute Beijing 100012China Beijing Engineering Technology Research Center of New Brazing Materials for Electronic Information Beijing 100012China

A multi-component alloy grade with liquidus temperature lower than 500℃was obtained by adding Ge and Mg elements on the basis of Al-Cu-Ag alloy,and the melting characteristics,as cast structure,tensile strength and section morphology of the alloy solder were *** results show that the solidus-liquidus temperature of the new designed Al-Cu-Ag-Ge-Mg solder is 468-491℃;in the vacuum environment,when heated to 530℃for 5 minutes,the surface of 5A05 aluminum alloy has a good wetting spread *** the same conditions,the tensile strength of the joint obtained by brazing is more than 50 MPa by tensile test at room temperature;combined with the observation and analysis of section *** addition of Ge can effectively reduce the solidus liquidus temperature of solder,and exist in the as cast structure and soldering seam with AlGe and *** presence of Ge element can inhibit the effect of other elements of the solder and Mg in the base metal,and alleviate the corrosion phenomenon between the solder and the base metal.

关键词： Al-Ag-Cu-Ge-Mg 5A05 Aluminum alloy melting characteristics

Microstructure and properties of the joints of ZrO2 ceramic/ stainless steel brazed in vacuum with AgCuTi active filler metal

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China Welding 2018年第2期27卷 52-56页

作者： Liu Xu Huang Xiaomeng Ma Huibin Shi Xiumei qi yuefeng Non-ferrous Metals and Rare Earth Research Institute Beijing 100012 China Engineering Research Center of New Brazing Materials for Electronic Information Beijing 100012 China

The ZrO2 ceranfic was successfully jointed to stainless steel by vacuum brazing with active filler metal. The AgCuTi active filler metal was used and the joining was performed at a temperature of 850 ℃ for 10 rain. The microstructures of the joints were characterized by metallographic microscopy, scanning electron microscopy （SEM）, and energy dispersive spectroscopy （EDS）. Metallographic microscopy analysis shows that the morphology of the cross section was a sandwich structure and the TiO is observed in the surface of ZrO2/ stainless steel. The diffusion and enrichment of the elements are the key roles in the brazing of ZrO2 ceramic and stainless steel. The formation of TiCu compounds inhibited the further diffusion of titanium into stainless steel or the ZrO2 ceramic to form TiO compound. In the experimental conditions, the average tensile strength is 80MPa for the joint of ZrO2 ceramic / AgCuTi/ stainless steel systems. A complete joint is formed between the ZrO2 ceramic and stainless steel with the leakage rate at the degree of 10 ^-12 Pa · m^3/s.

关键词： ZrO2 ceramic AgCuTi active filler metal vacuum active brazing technique