变耦合率法测量化学激光器小信号增益

为了评价化学激光器增益发生器模块的性能,采用变耦合率法对化学激光器的小信号增益系数进行了研究。实验中采用的稳定光学谐振腔由2块全反射平面镜、1块全反射凹面镜及1块输出耦合镜组成。将测量结果中存在的饱和光强、非输出损耗和小信号增益的三元拟合问题转化为二元数值问题。通过数值拟合得到了满足工程需求的数据结果,并对该结果进行了误差分析。应用数学方差分析发现平均值二对应的拟合曲线与实验测量结果符合得更好,化学激光器的输出功率存在极大值。

改进的变耦合率测增益法

本文建立的改进的变耦合率测增益法是建立在变耦合率测增益法（简称PT法）基础上的更为简化的测增益法，是一种适合于大功率且无适当探测光源的激光介质的小信号增益的测量。用改进的变耦合率测增益法，我们拟合得到了超音速运转COIL的小信号增益（约8×10-3／cm）；；这一结果同美国采用直接测量法的结果基本一致．

非链式脉冲DF激光器增益分布特性

为了研究非链式脉冲DF激光器的增益分布特性,在考虑谱线碰撞加宽和多普勒加宽对增益系数影响的基础上,运用变耦合率法给出了计算增益系数的简便公式。利用光阑移动扫描采样法,实验测量了不同输出镜透过率条件下DF激光器增益区横截面上各采样点的激光输出功率。对于每个采样点,计算得到两个独立的增益系数,其标准差小于3%。激光平均增益系数为2.594 3 m-1,非输出损耗系数为1.243 5 m-1。对各采样点的增益系数进行二维插值,结果显示在激光增益区横截面上增益系数呈现中央高、边缘低的超高斯分布。研究成果可为非链式脉冲DF激光器谐振腔和电极结构设计提供依据,并可为该激光器的气体放电均匀性分析提供参考。

测均匀激光器增益的新方法

在变耦合率测激光器增益方法的基础上，通过测定最佳输出耦合率和适当的数字变换，得到确定激光介质小信号增益的新方法。该方法避免了变耦合率方程拟合法所存在的问题，

Analysis of Decadal Climate Variability in the Tropical Pacific by Coupled GCM

This study presents the spatial and temporal structures of the decadal variability of the Pacific from an extended control run of a coupled global climate model (GCM).The GCM used was version-g2.0 of the Flexible Global Ocean Atmosphere Land System (FGOALS-g2.0) developed at LASG/IAP.The GCM FGOALS-g2.0 re-produces similar spatial-temporal structures of sea surface temperature (SST) as observed in the Pacific decadal os-cillation (PDO) with a significant period of approximately 14 years.Correspondingly,the PDO signals were closely related to the decadal change both in the upper-ocean temperature anomalies and in the atmospheric circulation.The present results suggest that warm SST anomalies along the equator relax the trade winds,causing the SSTs to warm even more in the eastern equatorial Pacific,which is a positive feedback.Meanwhile,warm SST anomalies along the equator force characteristic off-equa-torial wind stress curl anomalies,inducing much more poleward transport of heat,which is a negative feedback.The upper-ocean meridional heat transport,which is asso-ciated with the PDO phase transition,links the equatorial to the off-equatorial Pacific Ocean,acting as a major mechanism responsible for the tropical Pacific decadal variations.Therefore,the positive and negative feedbacks working together eventually result in the decadal oscilla-tion in the Pacific.

Dual-Band Coupled-Line Bandpass Filter with Independently Tunable Bandwidths

This paper reports a novel dual-band coupled-line bandpass filter.Comprising a quadruple-mode coupled-line resonator,this proposed filter could filter signals on two frequency bands.After introducing two varactors,one of the four resonances could be continuously altered by changing the capacitance of the varactors,thus the two frequency bandwidths could be independently tunned.In this paper,the detailed explanation for its operation is given,and the agreement between the expected and practical performance sufficiently confirms the robustness and effectiveness of this proposed filter.

ENSO Variability Simulated by a Coupled General Circulation Model:ECHAM5/MPI-OM

The accurate simulation of the equatorial sea surlhce temperature （SST） variability is crucial for a proper representation or prediction of the El Nino-Southern Os- cillation （ENSO）. This paper describes the tropical variability simulated by the Max Planck Institute （MPI） forr meteorology coupled atmosphere-ocean general circulation model （CGCM）. A control simulation with pre-industrial greenhouse gases is analyzed, and the simulation of key oceanic features, such as SST, is compared with observa- tions. Results from the 400-yr control simulation show that the model＇s ENSO variability is quite realistic in terms of structure, strength, and period. Also, two related features （the annual cycle of SST and the-phase locking of ENSO events）, which are significant in determining the model＇s performance of realistic ENSO prediction, are further validated to be well reproduced by the MPI cli mate model, which is an atmospheric model ECHAM5 （which fuses the EC tbr European Center and HAM for Hamburg） coupled to an MPI ocean model （MPI-OM）, ECHAMS/MPI-OM.

Continuous-Variable Entanglement Generation from a Four-State Atom under Raman Excitation

We investigate the generation and the evolution of continuous-variable(CV) entanglement from a laserdriven four-state atom inside a doubly resonant cavity under Raman excitation.Two transitions in the four-state atom independently interact with the two cavity modes,while two other transitions are driven by coupling laser fields.By including the atomic relaxation as well as cavity losses,we show that the CV entanglement with large mean number of photons can be generated in our scheme.We also show that the intensity of the coupling laser fields can influence effectively the entanglement period of the cavity field.Different from the conventional resonant excitation scheme where zero one-photon detuning are required,it is found that the intensity and period of entanglement between the two cavity modes as well as the total mean photon number of the cavity field can be adjusted by properly modulating the frequency detuning.

Transfer efficiency optimal control of magnetic resonance coupled system of wireless power transfer based on frequency control

In order to suppress the fast decrease of the transfer efficiency of magnetic resonance coupled wireless power transfer system(MRCWPTS) with distance increase,this paper investigates the impact factors of the system transfer efficiency and is,then formulates a new efficiency optimal control method based on frequency control.Based upon this control method two optimal control schemes are designed to achieve transfer efficiency control of the system.Simulations and experiments show that the proposed efficiency optimal control method can effectively stabilize the system transfer efficiency in a certain range so as to successfully solve the subtle issue of transfer efficiency variation with distance.