电子束泵浦KrF激光放大器增益与吸收的测量

为研制百焦耳级ＫｒＦ激光放大器，发展ＭＯＰＡ系统，我们用自探测法在百焦耳级电子束泵浦ＫｒＦ激光装置上进行了激光放大器的增益与吸收的测量。泵浦率约为０．６７ＭＷ／ｃｍ￣２，激光介质为８９．６％Ａｒ：１０％Ｋｒ：０．４％Ｆ＿２的混合气体，总气压０．２５ＭＰａ，实验测得激光放大器的小信号增益系数ｇ＿０＝６．６％ｃｍ￣（－１）、非饱和吸收系数α＿ｎ＝０．９３％ｃｍ￣（－１）、饱和光强Ｉ＿ｓ＝２．５ＭＷ／ｃｍ￣２。     

电子束泵浦KrF激光放大器增益与吸收的测量

为研制百焦耳级ＫｒＦ激光放大器，发展ＭＯＰＡ系统，我们用自探测法在百焦耳级电子束泵浦ＫｒＦ激光装置上进行了激光放大器的增益与吸收的测量。泵浦率约为０．６７ＭＷ／ｃｍ￣２，激光介质为８９．６％Ａｒ：１０％Ｋｒ：０．４％Ｆ＿２的混合气体，总气压０．２５ＭＰａ，实验测得激光放大器的小信号增益系数ｇ＿０＝６．６％ｃｍ￣（－１）、非饱和吸收系数α＿ｎ＝０．９３％ｃｍ￣（－１）、饱和光强Ｉ＿ｓ＝２．５ＭＷ／ｃｍ￣２。     

北京谱仪上J/ψ→γπ~0、γη、γη—'→3γ衰变道的分支比测量

分析Ｊ／ψ衰变终态为三个光子的衰变道，测量得到了衰变道Ｊ／ψ→γπ０和Ｊ／ψ→γη’的分支比分别为Ｂｒ（Ｊ／ψ→γπ０）＝（４．６±１．１）×１０－５和Ｂｒ（Ｊ／ψ→ッη＇）＝（４．１２±０．８２）×１０－３；相对分支比Ｆ（Ｊ／ψ→γη’）／Ｆ（Ｊ／ψ→γη）＝４．７９±０．８５，在实验误差范围内与两个理论模型的预言都能一致。     

Dye Laser-pumped Cr: LiSrAIF_6 Laser

ＤｙｅＬａｓｅｒ－ｐｕｍｐｅｄＣｒ：ＬｉＳｒＡＩＦ_６Ｌａｓｅｒ￥ＷＵＸｉｎｇ（Ｄｅｐｔ．ｏｆＰｒｅｃｉｓｉｏｎＩｎｓｔｒｕｍｅｎｔＥｎｇｉｎｅｅｒｉｎｇ，Ｔｉａｎｊｉｎ３０００７２，Ｃｈｉｎａ）Ｔ．Ｏｋａｄａ，Ｋ．Ｋａｅｄａ（Ｄｅｐｔ．ｏｆＥｌｅｃ?..     

电源输出功率与效率的定量比较

在研究电源输出功率与效率的关系时,一般只做定性分析．本文试图对电源输出功率与效率做一般性定量比较．１　电源输出功率为最大时的条件１．１　输出功率如图１所示,电路消耗在负载电阻Ｒ上的功率可用下式表示：图１Ｐ＝Ｉ２Ｒ＝［Ｅ／（Ｒ＋ｒ）］２Ｒ＝Ｅ２Ｒ／［（Ｒ－ｒ）２＋４Ｒｒ］（１）……１．２　最大输出功率时的条件从（１）式可看出,仅当Ｒ＝ｒ时,Ｐ有最大值：Ｐｍａｘ＝Ｅ２／４ｒ２　输出功率与效率２．１　最大输出功率时的效率η＝ＰＰ总×１００％Ｐ总＝ＩＥ＝［Ｅ／（Ｒ＋ｒ）］Ｅ＝Ｅ２／（Ｒ＋ｒ）　　当电源有…     

同一个非动力学r矩阵所对应的有理Ruijsenaars—Schneid …

构造了有理Ｒｕｉｊｓｅｎａａｒｓ－Ｓｃｈｎｅｉｄｅｒ模型（ｎ＝２）的新的Ｌａｘ算子,发现相应的ｒ矩阵是非动力学的,它与Ｃａｌｏｇｅｒｏ－Ｍｏｓｅｒ模型具有相同的ｒ矩阵。     

球坐标系中矢量的微分

在球坐标（ｒ，θ，）中计算矢量的变化率，例如计算质点的加速度，需要先计算基底矢量ｅｒ，ｅθ，ｅ的微分ｄｅｒ ，ｄｅθ，ｄｅ，本文给出这三个微分．     

堆泵浦^3He—Ar—Xe体系的激光原理性实验

介绍了在ＣＦＢＲ－Ⅱ脉冲堆上进行的￣３Ｈｅ─Ａｒ─Ｘｅ体系的激光演示实验。当热中子注量率６×１０￣（１４）／ｃｍ￣２·ｓ，气体组配￣３Ｈｅ：Ａｒ：Ｘｅ＝３４．７：３４．７：０．２６７（ｋＰａ）时，获得波长λ＝１．７３μｍ、脉宽（ＦＷＨＭ）平均值７３８μｓ、峰值功率为毫瓦级的激光输出。同时对测得的光信号及其特性进行了分析。     

堆泵浦~3He－Ar－Xe体系的激光原理性实验

介绍了在ＣＦＢＲ－Ⅱ脉冲堆上进行的￣３Ｈｅ─Ａｒ─Ｘｅ体系的激光演示实验。当热中子注量率６×１０￣（１４）／ｃｍ￣２·ｓ，气体组配￣３Ｈｅ：Ａｒ：Ｘｅ＝３４．７：３４．７：０．２６７（ｋＰａ）时，获得波长λ＝１．７３μｍ、脉宽（ＦＷＨＭ）平均值７３８μｓ、峰值功率为毫瓦级的激光输出。同时对测得的光信号及其特性进行了分析。     

超球坐标下Li原子基态能量的快速收敛计算

将Ｌｉ原子２Ｓ态的波函数分解为两项之积，ψ＝ＸΦ，Ｘ＝ｅｘｐ［－α（ｒ１＋ｒ２＋ｒ３）］，而Φ向以九维超球谐为投影函数而构造的Ｓ３置换群的二维不可约表示的基函数展开。Ｓｃｈｒｏｄｉｎｇｅｒ方程转化为一起球径耦合微分方程。再利用广义Ｌａｇｕｅｒｒｅ函数展开法对其求解，从而得到一广义能量本征方程，给出了库仑势及有关超球角函数在非对称九维超球谐之间矩阵元的简单解析式，可由一起几何函数４Ｆ３：（Ａ，Ｂ，Ｃ，Ｄ；Ｅ，Ｆ，Ｇ；１）的线性组合表示。取超球谐函数的子集（ｌ１＝ｌ２＝ｌ３＝０），基态１２Ｓ的本征能量在超球角方向的收敛速度加快，首次用非变分法得到了优于Ｈａｒｔｒｅｅ－Ｆｏｃｋ精度的基态能量。结果表明本文给出的方法是对直接超球谐广义Ｌａｇｕｅｒｒｅ函数展开法（ＨＨ－ＧＬＦ）的一个非常有效的改进。     

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.