Effect of power-law nonlinearity on ${ \mathcal P }{ \mathcal T }$-symmetric optical system with fourth-order diffraction

Gaussian-type soliton solutions of the nonlinear Schrödinger (NLS) equation with fourth order dispersion, and power law nonlinearity in the novel parity-time (${ \mathcal P }{ \mathcal T }$)-symmetric quartic Gaussian potential are derived analytically and numerically. The exact analytical expressions of the solutions are obtained in the first two-dimensional (1D and 2D) power law NLS equations. By means of the linear stability analysis, the effect of power law nonlinearity on the stability of Gauss type solitons in different nonlinear media is carried out. Numerical investigations do confirm the stability of our soliton solutions in both focusing and defocusing cases, specially around the propagation parameters.     

聚芳香杂环甲烯的三阶非线性光学效应与时间分辨光克尔效应

合成了一系列聚芳香杂环甲烯,包括聚吡咯甲烯和聚噻吩甲烯.采用四波混频法研究材料的共振三阶非线性光学效应(λ＝532nm),其共振二阶超分子极化率γ三阶非线性光学系数分别达到10^-30esu和10^-8esu.选择具有良好溶解性、成膜性的聚吡咯对二甲氨基苯甲烯(PPDMAB),采用飞秒时间分辨光克尔效应方法研究材料的非共振三阶非线性光学效应(λ=790nm).实验表明,翠绿亚胺碱溶液的光克尔信号仅表现一超快响应的成分,归功于π电子云扭转产生的非共振激发.PPDMAB的非共振二阶超分子极化率γ三阶非线性光学系数分别达到γ=5.78×10^-32esu和χ⁽³⁾=1.26×10^-10esu.     

推拉型偶氮化合物的三阶非线性和光学双稳效应

本文报道从推拉型偶氮化合物中测得了非常高的三阶非线性极化率,X~(3)～6×10~(→3)esu.这对于引起光学双稳现象是至关重要的.利用波长为488nm的氩离子激光为光源,从这类材料掺杂的玻璃态聚合物薄膜的Kretschmann型态中,进一步观察到了光学双稳现象.与此同时,联系这类材料的顺反异构化反应历程,从电子吸收机制或光诱导的折射率变化机制对有关问题进行了讨论.     

0.14 THz高分辨力成像雷达信号处理

为适应0.14 THz超高分辨雷达实时成像的需求,开发了基于CPU+GPU+FPGA的硬件架构和成像处理算法,算法以距离-多普勒为原型,引入L类维格纳分布变换提高横向分辨力,用Keystone变换方法对越距离单元徙动进行校正,并开发了系统非线性补偿算法。在载频0.14 THz、带宽5 GHz雷达样机上进行了逆合成孔径雷达成像试验,获得了3 cm3 cm的成像分辨力和实时成像能力,验证了信号处理方法的有效性。     

Nonlinear optical behaviors in a silver nanoparticle array at different wavelengths

The optical nonlinearities of an Ag nanoparticle array are investigated by performing Z-scan measurements at the selected wavelengths (400, 600, 650, and 800 nm). The nonlinear refraction index in the resonant region (around 400 nm) exhibits a significant enhancement by two orders compared with that in the off-resonant region (around 800 nm)), and exhibits an sign alternation of the resonant nonlinear absorption, which results in a negligible nonlinear absorption at a certain excitation intensity. Moreover, a low degree of nonlinear absorption was measured at the edges of the resonant region (600 and 650 nm), which is attributed to the competition of the saturated absorption and the two-photon absorption processes.     

基于偏振无关分束器的两光子部分纠缠态的简化浓缩方案

经由偏振无关的光学分束器实现对未知两光子部分纠缠态的纠缠浓缩,包括利用单光子探测器的线性光学浓缩方案,和利用弱交叉Kerr非线性媒质、零拍探测的浓缩方案。两对部分纠缠的光子对中各一个信号光子同时通过偏振无关分束器后,当探测到分束器输出模中各有一个光子时,剩余的两光子将处于最大纠缠态。与以前的浓缩方案相比较,我们的浓缩方案不需要额外的Hadmard门对信号光子施加作用,所需要的光学器件较少,这增加了方案在实验实现上的可行性。     

Adomian Decomposition Method Using Integrating Factor

This paper proposes a new Adomian decomposition method by using integrating factor.Nonlinear models are solved by this method to get more reliable and efficient numerical results.It can also solve ordinary differential equations where the traditional one fails.Besides,the complete error analysis for this method is presented.     

亚皮秒级时间分辨率的光取样示波器实验样机

利用自行开发的高稳定、低抖动和重复频率可调的“σ”型被动锁模光纤激光器作为高性能光学取样源,与待测的80 Gb/s光脉冲信号同时输入到100 m高非线性光纤中,通过四波混频效应实现了对被测光信号的全光采样。然后利用自行开发的数字信号处理与计算机图形显示软件,精确地重现了被测试的基于RZ码型的80 Gb/s光脉冲信号波形图。同时,还利用该光学取样示波器实验样机系统对重复频率为10 GHz、脉宽为1.8 ps的商用半导体主动锁模激光器的输出波形进行测量,所显示的脉冲宽度值为2.0 ps。这表明开发出的实验样机系统的时间分辨率优于900 fs。     

科学级光学CCD非线性特性测试

在惯性约束聚变(ICF)实验研究中,科学级CCD常和光谱仪、条纹相机等诊断设备组合进行冲击波等物理过程的时间、空间方面的诊断研究。非线性作为CCD一个非常重要的性能参数,在实验的后处理过程中有着相当重要的作用,实验分别采取固定曝光时间,改变光源的出射功率密度、固定光源的输出功率密度和改变CCD的曝光时间两种方案对TEK 512×512DB CCD的非线性特性进行测试,计算得到两种实验方案下该CCD的非线性度分别为0.595%和0.508%,并通过对各种因素的评估得到第一种标定方案为最佳,为科学级CCD的性能参数自动测试平台的建立提供参考。