Effect of technological parameters on optical performance of fiber coupler

To find out the influence of technological parameters on optical performance of fused optical fiber device, the fiber coupler was served as subject investigated by using the fused biconical taper machining as experimental setup. Fused fiber coupler＇s optical performances such as insertion loss, excess loss, directivity and uniformity were tested with the optical test system that was constituted of tunable laser and optical spectrum analyzer. Especially the relationship between optical performance and drawing speed was investigated. The experimental results show that the optical performance is closely related to process conditions. At fused temperature of 1 200℃, there exists a drawing speed of 150μm/s, which makes the device＇s performance optimum. Out of this speed region, the optical performance drops quickly. At drawing speed of 200μm/s, the excess loss is relatively small when the fused temperature is above 1 200 ℃. So the technological parameters have close relationship with optical performance of the coupler, and the good performance coupler can＇t get until the drawing speed and fused temperature match accurately.     

Novel manufacturing method of optical fiber coupler

Based on the coupling mode theory that the coupling ratio of fiber coupler changes periodically with center distance of two optical fibers, a novel manufacturing method of optical fiber couplers was developed with fused biconical taper experimental system. Its fabrication process is that the fiber is fused but not stretched when light begins to split, and the reduction of diameter of fiber is dependent on the theological characteristic of the fused fiberglass. The performance of the coupler was tested. The results show that the performance of the novel optical fiber coupler meets the performance expectations, and its diameter of coupling region （about 30 μm） is twice as long as that of classical fused biconical taper coupler （about 16 μm）, so the default, that is, the device is easy to fracture, is restrained and the reliability is greatly improved.     

Relationship between rheological manufacturing process and optical performance of optical fiber coupler

Through theoretical analysis and experiments, the viscoelastic mechanical model of optical fiber coupler in the process of fused biconical taper was established, and the numerical analysis in non-uniform temperature field was made. The results show that the rheological parameters, such as drawing speed and fused temperature, have a tremendous influence on stress distribution and performance of optical fiber coupler, especially the influence of fused temperature. The change of fused temperature by 5 ℃ can lead to the change of the maximum stress by 30% and stress difference by 20% in the same cross section. The change of temperature gradient by 3% can result in the change of stress difference by 90%. In the present condition of rheological technology, rheological defects such as crystallizations and microcracks are easy to generate in the optical fiber coupler.     

Experimental measurement and numerical analysis of fused taper shape for optical fiber coupler

To find out the effect of the shape of fused taper region on the optical fiber coupler, the fiber couplers were fabricated at different drawing speeds with a six-axes fiber coupler machine. The results, which were obtained fi＇om the shape of fused taper region measured with microscope, show that there is a close correlation between the cone angle and optical performance of fiber coupler. High-performance fiber coupler cannot be obtained until rheological shape is controlled accurately. The numerical analysis model, which was built based on generalized Maxwell viscoelastic theory, is resolved with ANSYS software. The calculated results accord with the experimental data. It can apply a theoretic basis for forecasting the shape of fiber coupler fabricated under the conditions of different technological parameters.     

Structure analysis of optical fiber coupler with infrared spectrometry

To obtain excellent performance optical fiber couplers, the structural difference of SiO2 in couplers with different manufacturing techniques was investigated. With 740-FT-IR infrared spectrometric analyzer, the infrared absorption spectrum of SiO2 in couplers at different drawing velocities was measured, and two characteristic peaks in the wavenumber range of 650 - 2000 cm^-1 were observed. One characteristic peak is at about 943 cm^-1 , which is attributed to Si--O Si bond asymmetric stretching vibration, the other is at about 773 cm^-1 , which is attributed to Si--O--Si bond symmetric stretching vibration. From the infrared spectrum, it is found that the intensity and wavenumber of the characteristic peaks are related to the manufacturing technique of couplers. The characteristic peak atabout 943 cm^-1 becomes steeper when increasing the drawing velocity. At the drawing velocity of 150μm/s, the distance between the two characteristic peaks is maximum, and then the optical fiber coupler has excellent performance, indicating that the performance of the optical fiber coupler has a close relationship with the wavenumber of the two characteristic peaks.     

Different Synthesis Methods for Ordered Mesoporous Silicas And Their Characteristics Comparison

1　IntroductionInorganicmesoporousmaterialshaveahighpotentialforapplicationsinthefieldsofcatalysis,adsorption ,sepa rationprocesses,biologymaterials,novelopticalmaterialsetc.Mesoporousmaterialshaverapidlyattractedresearchinterestsinthefieldofphysics,chemistryandmaterialssince 1 990s.Oneofthemostrepresentativemesoporousmaterialsismesoporoussilicapreparedbyusingalkylquaternaryammoniumcationicsurfactantsastemplate[1 3 ].Recently ,themesoporoussilicahasbecomeoneofthemostactivefieldsofhost guestass…     

Strength and elastic properties of sandstone under different testing conditions

A laboratory experimental program performed on Wuhan sandstones was presented under monotonic loading, partial cyclic loading during loading path and sine wave cyclic loading with different strain rates to compare uniaxial compression strength and elastic properties （elastic modulus and Poisson ratio） under different conditions and influence of pore fluid on them. When the loading strain rates are 10^-5, 10^-4 and 10^-3/s, uniaxial compression strengths of dry sandstones are 82.3, 126.6 and 141.6 MPa, respectively, and that of water saturated sandstones are 70.5, 108.3 and 124.1 MPa, respectively. The above results show that the uniaxial compression strength increases with the increase of strain rate, however, variation of softening coefficient is insignificant. Under monotonic loading condition, tangent modulus increases with an increment of stress （strain） to a maximum value at a certain stress level, beyond which it starts to decline. Under the partial cyclic loading during loading path condition, unloading or reloading modulus is larger than loading modulus, and unloading and reloading moduli are almost constants with respect to stress level, especially unloading modulus. Under the sine wave cyclic loading condition, tangent modulus and Poisson ratio display asymmetric ‘X＇ shape with various strain, and the average unloading modulus is larger than the average loading modulus.     

A study on the bonding structure of CaO−SiO2 slag by means of molecular dynamics simulation

The investigation results of the bonding structure of CaO−SiO₂ slag by means of molecular dynamics simulation are presented. The characteristics of partial radial distribution functiong _ij(r) are in good agreement with the measurement of X-ray diffraction, and the variation ofQ _n with different SiO₄ tetrahedra following the change ofX _CaO is consistent with the results of Raman spectroscopy. The partial vibrational density of states Γ_Si(ω) shows that two bands appear in the range of 636–737 cm⁻¹ and 800–1200 cm⁻¹ respectively which are also consistent with Raman spectroscopy. Project supported by Shanghai Natural Science Foundation.     

Catalytic wave of cobalt and its analytical application in rapid determination of trace cobalt in complex zinc electrolyte solution

Ｂｅｃａｕｓｅｉｔｓｍｅｃｈａｎｉｓｍｉｓｒａｔｈｅｒｃｏｍｐｌｅｘ,ｔｈｅｐｏｌａｒｏｇｒａｐｈｉｃｗａｖｅｏｆｃｏｂａｌｔ(Ⅱ)ｄｉａｃｅｔｙｌｄｉｏｘｉｍｅ(ＤＭＧ)ｓｙｓｔｅｍｈａｓｂｅｅｎｅｘｐｌａｉｎｅｄａｓｃａｔａｌｙｔｉｃｈｙｄｒｏｇｅｎ[1～3],ｉｒｒｅｖｅｒｓｉｂｌｅｃｏｍｐｌｅｘａｄｓｏｒｐｔｉｏｎ[4,5],ｐａｒａｌｌｅｌｃａｔａｌｙｓｉｓ[6]ｗａｖｅｓａｎｄｓｏｏｎ[7].Ｂａｓｅｄｏｎｔｈｅｃａｔａｌｙｔｉｃｗａｖｅｏｆｔｈｅｓｙｓｔｅｍ,ｓｏｍｅｈｉｇｈｌｙｓｅｎｓｉｔｉｖｅｐｏｌａ…     

Synthesis and photophysical and electrochemical properties of new cyclometalated platinum complex containing oxadiazole ligand

A new cyclometalated platinum complex containing 2, 5-bis（naphthalene-1-yl）-1,3,4-oxadiazole ligand was synthesized and characterized. The UV-Vis absorptions and photoluminescent properties of the ligand and its platinum complex were investigated A characteristic metal-ligand charge transfer absorption peak at 439 nm in the UV spectrum and a strong emission peak at 625 nm in the photoluminescence spectrum were observed for this complex in dichloromethane. Cyclic voltammtry （CV） analysis shows that the EHOMO （energy level of the highest occupied molecular orbital） and ELUMO （energy level of the lowest unoccupied molecular orbital） of the platinum complex are about -5.69 and -3.25 eV, respectively, indicating that the oxadiazole-based platinum complex has a potential application in electrophosphorescent devices used as a red-emitting material.     

Electrochemical kinetics of gold dissolving in alkaline thiourea solution

1 INTRODUCTIONEssentially , determination of electrode reac-tion mechanism is just the determination of thecourse of electrode reaction and the rate-determi-ning step[1 5]. Based on the previous results[6 11],gold dissolution mechanism undergoes the follow-ing courses in alkaline thiourea solution: adsorp-tion of thiourea on active points of electrode sur-face and formation of Au[SC(NH2)2]ads; chargetransfer fromactive gold atomto thiourea moleculeand formation of Au[SC(NH2)2]a+ds; Au-…     

Sorption Behavior and Mechanism of Indium（ Ⅲ ） onto Amino Methylene Phosphonic Acid Resin

The sorption behavior of amino methylene phosphonic acid resin (APAR) for In(III) was investigated. Experimental results show that In(III) adsorbed on APAR can be eluted with 2mol·L⁻¹ HCl. The apparent rate constant is k₂₉₈=1.50×10⁻⁵s⁻¹. The sorption behavior of APAR for In(III) obeys the Freundlich isotherm. The thermodynamic parameters of sorption, enthalpy change ΔH, free energy change ΔG and entropy change ΔS of sorption (APAR) for In(III) are 24.1kJ·mol⁻¹, −35.1kJ·mol⁻¹ and 200J·mol⁻¹·K⁻¹, respectively. The coordination molar ratio of the functional group of APAR to In(III) is 2∶1. The sorption mechanism of APAR for In(III) was examined by IR spectrometry. XIONG Chun-hua: Born in 1959 0 This project was supported by Foundation of Zhejiang Provincial Education Bureau(No.20010677) and Lishui Science and Technology Bureau(No.2001012).     

Preparation of Mg-Ti System Alloy and FGM with Density Gradient by Spark Plasma Sintering Technique

A new kind of functionally graded materials (FGM) with density gradient has come to show great potentials as flier-plates for creating quasi- isotropic compression waves. In order to meet the demand of lower density in the front face for such flier-plate, Mg with a low density of 1.74g/cm^3 is selected to make a Mg-Ti FGM. Mg- Ti alloys with various weight ratios were siatered by spark plasma sintering ( SPS ) technique at relative low temperatures, and the processing of densification is mainly investigated. It is found that, up to 75wt% Ti , the Mg- Ti alloys can be fully densified at 560℃ due to the conglutinnation of Mg and the formation of a small amount of Mg- Ti solid solution. Finally, the Mg- Ti FGM with a density gradient from 1.74g/cm^3 to 3.23 g/cm^3 is successfully fabricated.     

Investigation on the surface active sites variation of mineral dusts

Ｔｈｅｇｒｏｕｐｏｆｎａｔｕｒａｌｍｉｎｅｒａｌｄｕｓｔｓｒｅｌａｔｅｓｔｏｔｈｅｉｒｂｉｏｌｏｇｉｃａｌａｃｔｉｖｉｔｙａｎｄｃｏｎｔｒｏｌｓｔｈｅｉｒｆｅａｔｕｒｅａｎｄｃｏｎｔｒｉｂｕｔｉｏｎｏｆｓｕｒｆａｃｅａｃｔｉｖｅｓｉｔｅｓａｎｄｉｎｆｌｕ ｅｎｃｅｓｏｎｔｈｅｐｒｏｃｅｓｓｏｆｔｈｅｉｒｓｕｒｆａｃｅ/ｃｅｌｌｐｈｙｃｏ ｃｈｅｍｉｓｔｒｙ[1] .1　ＥｘｐｅｒｉｍｅｎｔａｌＴｈｅｓａｍｐｌｅｓｕｓｅｄｉｎｅｘｐｅｒｉｍｅｎｔａｌｗｅｒｅｆｉ ｂｒｏｕｓｂｒｕｃｉｔｅｆｒｏｍｔｈｅｓｏｕ…     

Electrochemical behavior of diverse vanadium ions at modified graphite felt electrode in sulphuric solution

PAN-based graphite felt (PGF) treated in 98% sulphuric acid for 5 h and then kept at 450 ℃ for 2 h was evaluated for their electrochemical performance as electrodes of vanadium redox battery (VRB). Structure and characteristic of treated PAN-based graphite felt (TPGF) were determined by means of Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy, Brunauer-Emmett-Teller surface area analysis and VRB test system. The results show that the acid and heat synergistic effect increase the number of —COOH functional groups on the PGF surface, and the PGF is eroded by sulphuric acid oxidation, resulting in the surface area increases from 0.31 m2/g to 0.45 m2/g. The V(Ⅱ)/V(Ⅲ) redox reaction is electrochemically reversible on the TPGF electrode, while the V(Ⅳ)/V(Ⅴ) couple is a quasi reversible process. The diffusion coefficients of the oxidation for V(Ⅳ)/V(Ⅴ) obtained from the scope of peak current Ip vs scan rate v1/2 is 4.4×10-5 cm2/s. The improvement of electrochemical activity for the electrode is mainly ascribed to the increase of the number of —COOH groups on the TPGF, which behaves as active sites catalyzing the vanadium species reactions and accelerating electron transfer reaction and oxygen transfer.     

Electrochemical behaviors of gold and its associated elements in various complex agent solutions

1　INTRODUCTIONGoldisquitestableanddifficulttodissolveinacommonmineralacid .However ,becausethereisadelectroniclayerunfilledingoldatomicstructure ,goldcanbecombinedwithmanychemicalagentstoformstablecomplexions,causingthepotentialofgoldinasolutiontodecreaseandgoldtodissolveinthesolutioneasily .Basedonthisprinciple ,cyanideisanefficientlixiviatingagentofgold ,andhasbeenwidelyusedtoextractgoldfrom primaryandsecondaryresources .However ,itisthemosttoxicandnotbeneficialtoen vironmentprotection…     

Direct rapid determination of traces of sulfide in environment samples

An improved ethylene blue method for determination of sulfide is developed. It has been adapted to a direct determination of sulfide by both common spectrophotometric method and total differential spectrophotometric method. In common spectrophotometric method, the calibration curve is A=1.69ρ+0.006 and the correlation coefficient is 0.9994.The apparent molar absorptivity is 5.42×104 L*mol-1*cm-1 and calibration curve is liner when ρ is in the range of 0-0.9 mg*L-1. In total differential spectrophotometric method, the calibration curve is A=9.25ρ+0.004 and the correlation coefficient is 0.9996. The apparent molar absorptivity is 2.96×105 L*mol-1*cm-1and calibration curve is liner when ρ is in the range of 0-0.10 mg*L-1. The sensitivity of this method is increased significantly compared with the former ethylene blue method. The speed of reaction is also faster than the former one. The limit of detection is found to be 1.0 ng*mL-1 by both common spectrophotometric method and total differential spectrophotometric method. Ten replicate analyses of a sample solution containing 100 ng*mL-1sulfide give a relative standard deviation of 1.8%. The effects of various cations and anions on the determination of sulfide are studied and procedures for removal of interference is described. The method is used for the determination of sulfide in environment samples with satisfactory results.     

Microstructural Probing of （1-x） GeS2- x Ga2S3 System Glasses By Raman Scattering

Roman scattering measurement of （ 1 - x ） GeS2-x Ga2S3 system glasses was conducted in order to understand the microstructural change caused by the addition of Ga2S3 . According to the change of Raman spectra with the addition of Ga2S3, two main structural transformations were deduced ： the gradual enhancement of ethane- like structural units S3 Ge- GeS3 （ 250 cm ^- 1） and S3 Ga- GaS3 （270 cm ^- 1 ） and the appearance of charge imbalanced units [ Ga2 S2 （ S1/2 ）4 ]^2- and [Ga（ S1/2 ）4 ]^- . And this change of structural aspect seems to give as a clue to understanding the cause of the increased rare-earth solubility.     

光纤熔融拉锥中拉力控制方法与电磁力仿真

针对保偏光纤耦合器熔融拉锥制造过程中拉力控制问题,提出一种新的计算机在线拉力控制方法.拉力控制系统由计算机、拉伸机构、圆光栅及控制电路组成,通过检测光纤支架的旋转角度、改变线圈中的电流,控制永磁铁与线圈间的电磁力,实现对拉伸力的实时控制.分析电磁力和拉力的关系,建立永磁铁和线圈的三维有限元模型,确定永磁铁的运动轨迹,并对通电线圈的磁场分布和电磁力进行仿真,得到线圈中的电流、支架旋转角度和拉力的关系式.仿真结果表明拉力控制良好,控制误差约为1.03%.     

Surface modification of magnesium hydroxide by γ-aminopropyltriethoxysilane

Magnesium hydroxide（MH）,which is commonly used as a halogen-free flame retardant filler in composite materials,was modified by silanization reaction with γ-aminopropyltriethoxysilane （γ-APS） in aqueous solution at different pH values （pH range from 8.0 to 12.0）. The surface properties of grafted γ-APS on MH surface as a function of solution pH value were studied using elemental analysis,Fourier transform infrared spectroscopy and zeta potential measurement. The results show that hydrolysis and condensation of γ-APS are activated in alkaline solution and lead to multilayer adsorption of γ-APS molecules on the surface of MH. The type of adsorption orientation of γ-APS on MH surface is a function of coverage density that is altered by changing solution pH value. At low coverage density （e.g. 55 nm^-2）,γ-APS molecules are preferentially adsorbed to the surface with the silicon moiety towards the surface,and increasing coverage density （e.g. 90 nm^-2） leads to parallel orientation. At an even higher coverage density （e.g. 115 nm^-2）,γ-APS molecules bond to the surface with the amino moiety towards the surface.