基于非线性材料二次谐波与混频特性非逻辑门运算的全光实现

Optics has already been proved as a successful candidate for conducting parallel logic, arithmetic and algebraic operations. Several all-optical data processors were proposed since last few decades. To implement these systems, different data encoding decoding techniques such as polarization encoding, tristate, quartenary state, multivalued state, symbolic substitution technique etc. have already been proposed. All these are done to use optics in a suitable platform. We propose here a new concept of encoding data by adopting frequencies variation technique for conducting a inversion operation successfully.     

掺锗硅基高非线性光纤超连续光源研究

利用非线性偏振旋转锁模掺铒光纤激光器和1100m长的掺锗硅基高非线性光纤制作了超连续光源,获得了从1150～1750nm的超宽带输出光谱,其中1150～1350nm波段光谱起伏小于3dB,1600～1700nm波段平坦度优于1dB,并有很好的向长波延展空间。光谱展宽的机理为孤子分裂与受激拉曼散射,而四波混频使光谱进一步展宽。     

杨氏双缝干涉实验的光谱变化

从理论和实验上研究了当部分相干光照射在双缝上时,杨氏双缝干涉实验干涉场中的光谱变化.指出干涉场中的归一化光谱在某些空间点处出现了蓝移,在另外一些空间点处出现了红移,而在这些空间点的中间,光谱分裂为等值的两条,出现了光谱开关现象.发现当观察点从轴上向轴外移动的过程中,在很多空间观察点处都出现了光谱开关现象.此外,研究结果还表明光谱相干度将对光谱的移动和光谱开关现象产生重要的影响.     

概率远程制备多粒子GHZ纠缠态

利用一个(N 1)粒子部分纠缠Greenberger-Home-Zeilinger(GHZ)态作为量子通道,提出了概率远程制备N粒子GHZ态的两个方案.我们考虑了怎样远程制备一个任意的GHZ态,即两个参数α和β都是复数的情况.此外,计算了远程制备总的成功概率和需要的经典信息量.     

The semiclassical modified nonlinear Schrödinger equation I: Modulation theory and spectral analysis

We study an integrable modification of the focusing nonlinear Schrödinger equation from the point of view of semiclassical asymptotics. In particular, (i) we establish several important consequences of the mixed-type limiting quasilinear system including the existence of maps that embed the limiting forms of both the focusing and defocusing nonlinear Schrödinger equations into the framework of a single limiting system for the modified equation, (ii) we obtain bounds for the location of the discrete spectrum for the associated spectral problem that are particularly suited to the semiclassical limit and that generalize known results for the spectrum of the nonselfadjoint Zakharov-Shabat spectral problem, and (iii) we present a multiparameter family of initial data for which we solve the associated spectral problem in terms of special functions for all values of the semiclassical scaling parameter. We view our results as part of a broader project to analyze the semiclassical limit of the modified nonlinear Schrödinger equation via the noncommutative steepest descent procedure of Deift and Zhou, and we also present a selfcontained development of a Riemann-Hilbert problem of inverse scattering that differs from those given in the literature and that is well adapted to semiclassical asymptotics.     

Steady state statistics of driven diffusions

We consider overdamped diffusion processes driven out of thermal equilibrium and we analyze their dynamical steady fluctuations. We discuss the thermodynamic interpretation of the joint fluctuations of occupation times and currents; they incorporate respectively the time-symmetric and the time-antisymmetric sector of the fluctuations. We highlight the canonical structure of the joint fluctuations. The novel concept of traffic complements the entropy production for the study of the occupation statistics. We explain how the occupation and current fluctuations get mutually coupled out of equilibrium. Their decoupling close-to-equilibrium explains the validity of entropy production principles.     

脉冲幅度均匀化的有理谐波锁模光纤激光器

提出并实现了一种脉冲幅度可均匀化的有理谐波锁模光纤激光器。该激光器采用主动有理谐波锁模机制,可获得重复频率为整数倍调制频率的锁模脉冲信号。通过在光纤激光器谐振腔中添加非线性光纤放大环镜,并利用其反射率对输入信号强度的开关特性,实现对锁模脉冲信号的整幅。在1 GHz的调制频率下,分别获得了4 GHz和5 GHz重复频率的锁模脉冲信号输出,并且在一定的980 nm抽运功率下,可通过调节电光调制器的直流偏置电压大小以及调制信号的调制深度,使得脉冲幅度具有较好的均匀性。     

基于无约束非线性优化算法的光强自相关函数拟合

在光子相关光谱(PCS)颗粒测量技术中非线性累积反演方法是一种重要的算法。采用无约束非线性优化算法对反演过程中相关曲线的拟合问题进行了分析和研究, 实现了从任意初始值开始获取最优非线性拟合解, 并给出了算法的实现步骤。采用此方法对50 nm, 100 nm, 200 nm和500 nm的标准聚苯乙烯乳胶颗粒的实测光强自相关函数数据进行了拟合, 并反演了颗粒粒径, 与其他曲线拟合算法相比, 本算法不但对初始值的依赖性小, 而且得到的颗粒粒径更接近乳胶颗粒的标称直径, 测量误差更小。     

连续光条件下对LiNbO3∶Fe∶Mn晶体全息存储性能的理论研究

以双中心模型为基础,在低光强连续光条件下研究了LiNbO3∶Fe∶Mn晶体在稳态情况下的非挥发双光双步全息存储性能。采用数值方法,通过比较双中心模型中深(Mn2+/Mn3+)、浅(Fe2+/Fe3+)能级之间所有可能的电子交换过程,发现由隧穿效应引起的深浅能级之间直接电子交换过程对LiNbO3∶Fe∶Mn晶体总的空间电荷场大小起着决定性的作用。同时,这一电子交换过程对晶体非挥发全息存储性能也起着至关重要的作用。此外,通过相同实验条件下LiNbO3∶Fe∶Mn晶体与近化学比LiNbO3∶Fe晶体总的空间电荷场的比较,显示LiNbO3∶Fe∶Mn晶体在低抽运光和高记录光光强条件下有着比近化学比LiNbO3∶Fe晶体更佳的全息存储性能。     

Li2、LiH的激发态和Li2H的基态结构与势能函数

使用“对称性匹配簇-组态相互作用”方法,对Li2分子三重态的第一激发态、LiH分子的基态、单重态的第一和第二激发态的几何构型与谐振频率进行了优化计算.利用“群操作求和”方法分别对这4个态进行单点能扫描计算,并拟合出了相应各态的Murrell-Sorbie势能函数.使用多种方法对Li2H分子的基态结构进行优化,并用优选出的密度泛函(B3P86)方法对该分子进行了进一步的频率计算.结果发现Li2H分子的基态稳态结构为C2v构型,在此基础上用多体项展式理论导出了它的解析势能函数,其等值势能图准确再现了Li2H分子的结构特征和离解能.首次报导了该分子对称伸缩振动等值势能图中存在的两个对称鞍点,对应于反应LiH Li→Li2H,活化能大约为18.7×4.184 KJ/mol.