基于复振幅调制的半导体激光光束整形方法

为了改善半导体激光光束质量,使其能够满足大距离高精度干涉测量的要求,使用空间光调制器对半导体激光光束进行整形,提出了一种基于复振幅调制算法的光束整形方法。利用该方法可将半导体激光光束整形为准直性好、光强分布均匀的无像散基模高斯光束。通过光束质量分析对整形后的光束进行评估,实验结果显示整形后半导体激光光束在x和y方向的M2因子均趋于1,像散接近于0,验证了该光束整形方法的有效性。将提出的半导体激光光束整形方法应用于大距离干涉测量中,在8m处进行了微米级步进位移测量,与纳米位移工作台相比,所得结果达到了亚波长的测量精度。实验结果表明整形后的光束能够满足大距离高精度干涉测量的要求,验证了提出的半导体激光光束整形方法的可行性。     

平面波经小圆环衍射轴上光强特性分析

从标量衍射理论出发,采用瑞利-索末菲衍射边界条件,通过求解第一类瑞利-索末菲衍射积分得到平面波经圆环衍射后轴上的波函数,进而分析轴上的光强特性以及光强极值数量、位置和大小与衍射圆环内外孔径的关系.比较用传统的光强定义和精确定义得到的光强公式的偏差,以及偏差与内外半径的关系.并将圆环衍射向内半径为零和外半径为无穷大两个方向进行推广,即对圆孔和圆形障碍物两种情况下的衍射情况进行讨论.     

一种结合Transformer和CNN的散斑图复原网络

近年来,深度学习已成功应用于计算成像领域,并取得了显著的成果。目前,实现激光透过散射介质后的图像复原技术成为热门的研究课题,本文提出了一种包含双编码器的深度学习网络模型Trans＿CNN,从散斑图复原目标物图像,该网络融合了来自Transformer编码器和卷积神经网络编码器的信息,并将融合的编码信息传递给解码器获得复原结果,从散斑图中最大程度地学习全局特征和局部特征,从而更好地从散斑图复原出目标图像。实验结果证明Trans＿CNN网络在复原散斑图像方面具有更好的性能和复原图像质量较好。     

Near-field characteristics of highly non-paraxial subwavelength optical fields with hybrid states of polarization

The vectorial structure of an optical field with hybrid states of polarization(So P) in the near-field is studied by using the angular spectrum method of an electromagnetic beam. Physical images of the longitudinal components of evanescent waves are illustrated and compared with those of the transverse components from the vectorial structure. Our results indicate that the relative weight integrated over the transverse plane of the evanescent wave depends strongly on the number of the polarization topological charges. The shapes of the intensity profiles of the longitudinal components are different from those of the transverse components, and it can be manipulated by changing the initial So P of the field cross-section. The longitudinal component of evanescent wave dominates the near-field region. In addition, it also leads to three-dimensional shape variations of the optical field and the optical spin angular momentum flux density distributions.     

Spatiotemporal self-similar solutions for the nonautonomous (3+1)-dimensional cubicben quintic Grossben Pitaevskii equation

With the help of similarity transformation, we obtain analytical spatiotemporal self-similar solutions of the nonautonomous (3+1)-dimensional cubic-quintic Gross-Pitaevskii equation with time-dependent diffraction, nonlinearity, harmonic potential and gain or loss when two constraints are satisfied. These constraints between the system parameters hint that self-similar solutions form and transmit stably without the distortion of shape based on the exact balance between the diffraction, nonlinearity and the gain/loss. Based on these analytical results, we investigate the dynamic behaviours in a periodic distributed amplification system.     

Spatiotemporal self-similar solutions for the nonautonomous （3＋1）-dimensional cubic-quintic Gross-Pitaevskii equation

With the help of similarity transformation,we obtain analytical spatiotemporal self-similar solutions of the nonautonomous(3+1)-dimensional cubic-quintic Gross-Pitaevskii equation with time-dependent diffraction,nonlinearity,harmonic potential and gain or loss when two constraints are satisfied.These constraints between the system parameters hint that self-similar solutions form and transmit stably without the distortion of shape based on the exact balance between the diffraction,nonlinearity and the gain/loss.Based on these analytical results,we investigate the dynamic behaviours in a periodic distributed amplification system.     

平面波经小圆孔衍射轴上传播函数的特性

从标量衍射理论出发,采用瑞利-索末菲衍射边界条件,通过求解第一类瑞利-索末菲衍射积分得到的平面波经小圆孔衍射轴上波函数的精确解,分析并总结轴上光强极值数量、极值位置和极值大小的一般规律;比较用振幅表示光强和光强的精确表示之间的差异及用振幅表示光强的条件,为研究其他衍射问题的准确性提供了一准确的判断标准;又由于角谱理论和第一类瑞利-索末菲衍射积分的一致性,同时也就得到角谱理论在处理小孔衍射时不可积积分的解析表达式,为进一步研究小孔非傍轴衍射提供了新的方法。[编者按]