Phase properties of odd and even circular states

Phase properties of the even and odd circular states are studied within the Hermitian phase formalism of Pegg and Barnett. Exact analytical formulas for the distribution function and the variance of the phase operator are obtained and used to examine whether or not the even and odd circular states exhibit photon-number squeezing and phase squeezing.     

C60掺杂向列相液晶薄膜的激光诱导自衍射现象研究

利用Kirchhoff-Fraunhofer衍射积分原理研究了实验中观察到的C60掺杂垂直排列向列相液晶(5CB)液晶薄膜的远场衍射图样.模拟计算结果表明:实验中观察到的衍射圆环是不同实验参数的结果,并给出了确定衍射圆环结构的主要参数C1和C2.当C1和C2的符号相同时,远场会出现中心强度最大,向外逐渐减弱,分布尺度较小的细衍射环;当C1和C2的符号相反时,远场会出现中央较暗,向外逐渐增强,分布尺度较大的粗衍射环.衍射圆环的产生可由高斯光束通过非线性样品是引起附加相位的自相位调制现象来解释.将使液晶材料应用于光限幅等光子学领域.     

Generalization and propagation of spiraling Bessel beams with a helical axicon

A generalized type of spiral Bessel beam has been demonstrated by using a spatially displaced helical axicon (HA). The topological charge of the spiraling Bessel beams is determined by the order of the input Laguerre-Gaussian (LG) beam and the topological charge of the HA. The obtained spiraling Bessel beams have an LG type of modulation along their propagation direction and exhibit annihilation-reconstruction properties. Theoretical analysis is presented, including that of the stability, propagation distance, topological charge, and spiraling dynamic characteristics. The mathematical and numerical results show that the propagation distance and helical revolution of the spiraling Bessel beams can be controlled through choosing appropriate radius of the HA.     

线性正则变换中的泰伯效应

提出了在一定的条件下,周期函数经过线性正则变换,结果仍然是周期函数,即利用线性正则变换可以产生泰伯效应,并从理论上给出了证明,得出了产生泰伯效应的条件。推导了特殊形式的线性正则变换(菲涅耳衍射、分数傅里叶变换和Gyrator变换)产生泰伯效应的条件,通过数值模拟验证了Gyrator变换的自成像条件,证明了该理论的正确性,从而将泰伯效应推广到了线性正则变换域。     

复杂红外背景中运动小目标快速跟踪技术

在地面、海面、天空复杂背景下对红外小目标稳定跟踪是亟需解决的难题.为兼顾鲁棒性和实时性,以判别尺度空间跟踪算法为基础,应用可有效表征目标区域灰度突变特性和目标形状信息的广义结构张量算法作为特征提取方法.改进后的算法更适用于红外图像快速处理,能提高跟踪鲁棒性,且计算量小、效率高,目标特征维度低.为提高跟踪稳定性,依据置信...     

Propagation factor of electromagnetic concentric rings Schell-model beams in non-Kolmogorov turbulence

We derive an analytical expression for the propagation factor(known as M2-factor) of electromagnetic concentric rings Schell-model(EM CRSM) beams in non-Kolmogorov turbulence by utilizing the extended Huygens–Fresnel diffraction integral formula and the second-order moments of the Wigner distribution function(WDF). Our results show that the EM CRSM beam has advantage over the scalar CRSM beam for reducing the turbulence-induced degradation under suitable conditions. The EM CRSM beam with multi-rings far-fields in free space is less affected by the turbulence than the one with dark-hollow far-fields or the electromagnetic Gaussian Schell-model(EGSM) beam. The dependence of the M2-factor on the beam parameters and the turbulence are investigated in detail.