Cr4+在MgCaBa-铝酸盐玻璃中的发射及光学增益

研究了四价铬离子掺杂的MgCaBa-铝酸盐玻璃在近红外区的发射光谱,既有源于¹E—³A₂跃迁,位于1.18μm处的窄带,又有源于³T₂—³A₂范围在1.1～1.4 μm内的宽带,利用ASE(Amplified Spontaneous Emission)方法研究了其增益特性,测量了在 632.8nm激发下不同激发长度下的发射光谱,得到其光学增益系数在1.18μm和1.24 μm处分别为B_E=(0.7±0.04)mm^-1和B_T=(0.05±0.005)mm^-1,并根据这种材料的光谱性质,对其作为近红外可调谐激光介质的可能作出评估。     

J/ψ→Σ~0 “非汉字符号”~0 衰变研究(英文)

利用北京正负电子对撞机 (BEPC)上的北京谱仪 (BES)收集的 7 8× 1 0 6 个J ψ事例 ,研究了J ψ→Σ0 Σ0 衰变 .其衰变分支比为BR(J ψ→Σ0 Σ0 ) =( 0 97±0 0 4± 0 2 4 )× 1 0 - 3,角分布具有 dNdcosθ=N0 ( 1 +αcos2 θ)的形式 ,α值等于 -0 2 1± 0 2 7± 0 1 3 .     

在φ→3γ衰变末态分析中的运用

介绍了介子工厂 (DAΦNE)KLOE组的数据分析中运动学拟合程序TELESIS的运用 .利用KLOE 2 0 0 0年在e+e- 对撞能量Ecm =1 0 2 0MeV获取的部分数据开展→γη→ 3γ和→γπ0 → 3γ的分析 ,得到介子的产生截面σe+ e- →=( 4.0 4± 0 .0 4± 0 .2 4 ) μb ,以及→γπ0 → 3γ的分截面σ→γπ0 →3γ=( 5.3± 0 .3± 0 .6)nb .这些结果与理论预言以及俄国新西伯利亚的VEPP(CMD 2 ,SND ,ND各探测器 )的相应结果一致 .     

1.3μm偏振无关半导体光放大器单片集成模斑变换器

用金属有机化学气相外延生长并制作了 1.3μm脊型波导偏振无关半导体光放大器集成模斑变换器 ,器件有源区为同时采用压应变量子阱和张应变量子阱的混合应变量子阱结构以获得TE和TM偏振模式的增益平衡 ,模斑变换器采用一种新型脊型侧向锥形波导结构 ;集成模斑变换器的半导体光放大器远场发散角为 12°× 15° ,接近圆形光斑 ,与平头标准单模光纤耦合损耗为 - 2 .6dB ,在水平和垂直方向上的 - 1dB耦合对准容差分别为± 2 .3μm和± 1.6 μm ;在 2 0 0mA偏置电流下 ,半导体光放大器小信号增益近 2 4dB ,在 12 80～ 1340nm波长范围内偏振灵敏度小于 0 .6dB。     

NO分子A2Σ→X2Π双光子激光感生荧光光谱

以Nd∶YAG激光器抽运光学参变振荡器 /光学参变放大器做为激发源 ,得到了NO分子在 2 2 0～ 35 0nm波长范围内的双光子激光诱导荧光光谱 ,并将其归属于A2 Σ(ν′ =0 )→X2 Π(ν″ =1～ 8)跃迁 ,用最小二乘法拟合获得NO分子X2 Π态振动常量″ωe =(190 4 .7± 7.3)cm-1,″ωe ″xe =(14 .2± 1.2 )cm-1,″ωe″ye=- (0 .0 2 18± 0 .0 0 91)cm-1,及平衡位置的力常量k =(1.5 99± 0 .0 12 )× 10 3 N·m-1。计算了所得跃迁谱带的弗兰克康登因子及相对荧光强度 ,结果与实验观测值相符。这可为用激光诱导荧光光谱技术探测大气污染物NO分子提供理论及实验参考     

胶束增溶光度法测定土豆中微量铝

采用 Al( ) - CAS- CTMAB- OP胶束增溶分光光度法测定了土豆中的铝。实验表明 ,在 p H=6 .5的HAc- Na Ac缓冲溶液中 ,λmax=6 2 0 nm处 ,Al3 在 0— 0 .2 4 μg/ m L范围遵守朗伯 -比耳定律 ,回归方程、相关系数、回收率和 RSD分别为 :A=4 .773C- 0 .0 1 3、r=0 .9995 (n=4 )、98.8%— 1 0 2 %和 0 .5 3%。不同产地土豆样品中 Al含量为 :1号样品 1 6 8.8μg/ g,2号样品 1 6 7.0 μg/ g     

反相高效液相色谱法测定1-(4-硝基苯)-3-(5-溴-2-吡啶)-三氮烯

ZORBAX Eclipse XDB- C8(4.6× 1 5 0 mm,5 μm)色谱柱 ,乙腈流动相 ,流速 0 .6 0 m L/min,检测波长4 2 0 nm,反相高效液相色谱法测定 1 - (4-硝基苯 ) - 3- (5 -溴 - 2 -吡啶 ) -三氮烯。该法的线性范围为 1—1 0 .0 μg/m L,线性回归方程为 A=5 .91 5 4 .4 37C,相关系数 0 .9989,相对标准偏差为 0 .8973%(C=7.2 0 μg/m L,n=5 ) ,检出限为 0 .0 2 872 μg/m L,平均回收率在 93.2 %— 1 0 2 .2 %之间。     

J/ψ→π~03(π~+π~-)分支比的测定

用BESⅠ的 7.8× 1 0 6 J/ ψ数据更为精确地测定了J/ ψ→π0 3 (π+π- )和J/ ψ→ω2 (π+π- )的分支比 (Br(J/ ψ→π0 3 (π+π- ) ) =( 2 .52± 0 .0 6± 0 .4 3 ) % ,Br(J/ ψ→ω2 (π+π- ) ) =( 1 .3 1± 0 .0 9± 0 .2 1 ) % .同时对 4π不变质量谱和ωππ不变质量谱进行研究分析 ,试图观察是否存在有兴趣的信号 .     

高效液相色谱法测定2-苯基-4-对甲苯基-1,5-苯并硫氮杂-α-(丁二酰亚胺基)-β-内酰胺

本文采用 Hypersil- ODS2 (4 .6mm× 2 5 0 mm,5μm)色谱柱 ,乙腈 -水 (70∶ 30 )流动相 ,2 4 2 nm测定波长 ,建立了测定 2 -苯基 4 -对甲苯基 - 1,5 -苯并硫氮杂 艹卓 -α- (丁二酰亚胺基 ) -β-内酰胺高效液相色谱法。该法线性范围为 0— 0 .1mg/ m L,回归方程 A=2 .11× 10 8C- 3.10× 10 5,相关系数 r=0 .9995 ,相对标准偏差为0 .2 4 % (C=0 .0 6mg/ m L,n=5 ) ,检出限为 0 .0 5 μg/ m L。平均回收率在 97.1%— 10 2 .4 %之间。该法重现性好、灵敏度高、简单、快速、准确     

高效液相色谱法测定2-对甲氧基苯基-4-苯基-1,5-苯并硫氮杂-α-(丁二酰亚胺基)-β-内酰胺

应用高效液相色谱外标定量法对 2 -对甲氧基苯基 - 4 -苯基 - 1,5 -苯并硫氮杂 艹卓 -α- (丁二酰亚胺基 ) -β-内酰胺进行了测定。采用 Hypersil- ODS2 ( 4 .6mm× 2 5 0 mm,5 μm)柱 ,乙腈与水按 70∶ 30 ( V/ V)组成流动相 ,测定波长为 2 4 2 nm,该方法线性范围为 0— 0 .1mg/ m L ,回归方程 A=1.91× 10 8C- 3.82× 10 5,相关系数 r=0 .9994 ,相对标准偏差为 0 .72 %,检出限为 0 .0 5μg/ m L,平均回收率在 98.4 %— 10 1.8%之间。该法重现性好、灵敏度高、简单、快速。     

Theoretical analysis and simulation of conjugate heights for dual-conjugate AO system in lidar

A multi-conjugate adaptive optics （MCAO） can offer a possibility of widening field of view （FOV） characterized by the isoplanatic angle, and the choose of conjugate height becomes a basic problem for MCAO, which influences the size of iosplanatic angle. Considering the application of lidar, the isoplanatic angle＇s expressions of two deformable mirrors （DMs） MCAO for uplink and downlink are deduced. The effects of conjugate heights for dual-conjugate AO are thoughtfully discussed, and the isoplanatic angles are further analyzed. The results show that the isopanatic angle varies with the conjugate height and reaches the maximum as the conjugate height is at the optimal altitude. Moreover, the optimal conjugate height changes with the propagation distance.     

Quick single-photon detector with many avalanche photo diodes working on the time division

Due to the limit of response speed of the present single-photon detector, the code rate is still too low to come into practical use for the present quantum key distribution (QKD) system.A new idea is put up to design a quick single-photon detector.This quick single-photon detector is composed of a multi-port optic-fiber splitter and many avalanche photo diodes (APDs).Au of the ports with APDs work on the time division and cooperate with a logic discriminating and deciding unit driven by the clock signal.The operation frequency lies on the number N of ports, and can reach N times of the conventional single-photon detector.The single-photon prompt detection can come true for high repetition-rate pulses.The applying of this detector will largely raise the code rate of the QKD, and boost the commercial use.     

Characterization of PolyA and PolyC mismatches by Raman spectroscopy

A.C mismatches are studied by Raman spectral characterization of PolyA, PolyC, and their equimolar complex in solution of 0.14 mol/L Na ,pH7.0.Experimental results show that A·C mismatches occur to be A/B (mainly A) conformers, and unlike Watson-Crick base pairing, this kind of mismatches is stabilized by only one hydrogen bond involving cytosine N4H2 and adenine N7.The formation of A·C complex makes the base stacking interactions much stronger, and conformation of the backbone more ordered, which leads to obvious Raman hypochromic effect with some shifts in corresponding bands.     

Improvement of four-wave mixing-based wavelength conversion efficiency in dispersion shifted fiber by 40-GHz clock pumping

40-GHz clock modulated signal as a pump to improve the efficiency of four-wave mixing (FWM)-based wavelength conversion in a 26.5-km dispersion shifted fiber (DSF) is investigated. The experimental results demonstrate that the conjugated FWM component has higher intensity with the clock pumping than that with the continuous-wave (CW) light pumping. The improvement of FWM-based wavelength conversion efficiency is negligible when the pump power is less than Brillouin threshold. But when the pump power is greater than Brillouin threshold, the improvement becomes significant and increases with the increment of pump power. The improvement can increase up to 9 dB if pump power reaches 17 dBm.     

Multi-pulse operation of a Kerr-lens mode-locked femtosecond laser

Our experimental results show that the presence of a proper amount of negative group velocity dispersion is essential to multi-pulse operation of a Kerr-lens mode-locked femtosecond laser. We demonstrate that the pulse separations and the number of pulses contained within a cavity round trip are strongly dependent on the initial perturbations. The results allow us to get a better understanding on the influences of the convoluted self-phase modulation and intra-cavity dispersions on the stable multi-pulse oscillation in a Kerr-lens mode-locked femtosecond laser.     

Propagation of Helmholtz-Gauss beams in weak turbulent atmosphere

Based on the Rytov approximation of light propagation in weak turbulent atmosphere,the closed-form expressions of field and average irradiance of each one of the four fundamental families of Helmholtz-Gauss (HzG)beams:cosine-Gauss beams,stationary Mathieu-Gauss beams,stationary parabolic-Gauss beams,and Bessel-Gauss beams,which are propagating in weak turbulent atmosphere,are obtained.The results show that the field and average irradiance can be written as the product of four factors:complex amplitude depending on the z-coordinate only,a Ganssian beam.a factor of complex phase perturbation induced by atmospheric turbulence,and a complex scaled version of the transverse shape of the non-diffracting beam.The effect of weak atmospheric turbulence on irradiance distribution of the HzG beam can be ignored.     

An effective method for reducing speckle noise in digital holography

An effective method for reducing the speckle noise in digital holography is proposed in this paper.Different from the methods based on classical filtering technique,it utilizes the multiple holograms which are generated by rotating the illuminating light continuously.The intensity images reconstructed by a series of holograms generated by rotating the illuminating light possess different speckle patterns.Hence by properly averaging the reconstructed intensity fields,the speckle noises can be reduced greatly.Experimental results show that the proposed method is simple and effective to reduce speckle noise in digital holography.     

Influence of purity of HfO2 on reflectance of ultraviolet multilayer

The impurities in two kinds of HfO2 materials and in their corresponding single layer thin films were determined through glow discharge mass spectrum technology and secondary ion mass spectrometry(SIMS) equipment respectively.It was found that ZrO2 was the main impurity in the two kinds of HfO2 either in the original HfO2 materials or in the electron beam deposited films.In addition,the difference of Zr content in the two kinds of HfO2 single laver films was much laxger than that of the other impurities such as Ti and Fe.which showed that it was just ZrO2 that made the difference between the optical performance of the film products including the two kinds of HfO2.With these two kinds of HfO2 and the same kind of SiO2.we deposited HfO2/SiO2 multilayer reflective coatings at the wavelength of 266 nm.Experimental results showed that the reflectances of these two mirrors were about 99.85% and 99.15% respectively,which agreed well with the designed results what were based on the optical constants obtained from the corresponding single layer thin films.     

Speech enhancement by array crosstalk resistant ANC and spectrum subtraction

Microphone array-based speech enhancement has great importance for speech communications and speech recognition. To reduce the aperture of the microphone array and to increase the effect of the speech enhancement will greatly broaden the application areas of the microphone array. An array crosstalk resistant adaptive noise cancellation method is therefore presented. And then an improved spectral subtraction algorithm is further cascaded to obtain better enhancement results. Theoretic analysis and experiments indicate that the proposed scheme needs only a very small microphone array while it simultaneously achieves a higher SNR improvement. Besides, the proposed scheme can be used in many noisy environments and is easy for real-time implementation.