Vectorial partially coherent flat-topped beams and their nonparaxial propagation

The concept of vectorial partially coherent flat-topped beams is proposed, and their nonparaxial propagation in free space is studied in detail. Based on the vector Rayleigh diffraction integral formulae, the analytical propagation expressions for the cross-spectral density matrix of the polarized vectorial nonparaxial partially coherent flat-topped beams are derived and applied to study the nonparaxial propagation properties of vectorial partially coherent flat-topped beams. The effect of propagation parameters on the intensity and the coherence property of the nonparaxial vectorial partially coherent flat-topped beam is illustrated and analyzed comparatively with the corresponding paraxial results.     

非傍轴双曲余弦-高斯脉冲电磁光束远场特性

利用矢量瑞利-索末菲衍射积分公式,推导出了非傍轴部分空间相干部分光谱相干双曲余弦-高斯(ChG)脉冲电磁光束在自由空间传输时交叉谱密度矩阵的远场解析公式,并用来表示脉冲电磁光束的光谱密度(光强)和偏振度。结果表明,对非傍轴远场部分空间相干部分光谱相干ChG脉冲电磁光束,其非傍轴性主要由参数f, f决定,而离心参数、脉冲宽度和时间相干长度影响其非傍轴行为。非傍轴部分空间相干部分光谱相干高斯-谢尔模型脉冲电磁光束的远场传输可作为特例处理。     

非傍轴双曲余弦-高斯脉冲电磁光束远场特性

利用矢量瑞利-索末菲衍射积分公式,推导出了非傍轴部分空间相干部分光谱相干双曲余弦-高斯(ChG)脉冲电磁光束在自由空间传输时交叉谱密度矩阵的远场解析公式,并用来表示脉冲电磁光束的光谱密度(光强)和偏振度。结果表明,对非傍轴远场部分空间相干部分光谱相干ChG脉冲电磁光束,其非傍轴性主要由参数f, f决定,而离心参数、脉冲宽度和时间相干长度影响其非傍轴行为。非傍轴部分空间相干部分光谱相干高斯-谢尔模型脉冲电磁光束的远场传输可作为特例处理。     

Partially coherent vectorial cosh-Gaussian beams beyond the paraxial approximation

The concept of partially coherent vectorial nonparaxial cosh-Gaussian (ChG) beams is introduced, and their analytical propagation expressions for the cross-spectral density matrix in free space are derived by using the generalized vectorial Rayleigh diffraction integrals. Some interesting cases, in particular, the vectorial nonparaxial Gaussian-Schell-model (GSM) beams are discussed and treated as special cases of our general expressions. It is shown that the f and f_σ parameters play a crucial role in determining the vectorial property and nonparaxiality of partially coherent ChG beams, but the decentered parameter additionally affects their behavior.     

部分相干光束通过硬边光阑的推广光束传输M2因子

给出部分相干光通过硬边光阑后的强度二阶矩的计算公式，由此可得到部分相干光通过硬边光阑后的推广光束传输M^2因子。以部分相干高斯－谢尔模型光束为例，推导出相应的M^2因子，并作了数值计算和分析讨论。     

Coherent and incoherent combinations of partially coherent beams beyond the paraxial approximation

The concept of coherent and incoherent combinations of partially coherent beams is described and interpreted physically. Taking the Gaussian Schell-model (GSM) beam as a typical example of a partially coherent beam, the analytical propagation expressions for the coherent and incoherent combinations of GSM beams beyond the paraxial approximation are derived and illustrated numerically. Some special cases of the general results are analyzed.     

Propagation of the Wigner distribution function for partially coherent nonparaxial beams

On the basis of the Rayleigh-Sommerfeld diffraction integral, a closed-form propagation expression for the Wigner distribution function of partially coherent nonparaxial beams in free space is derived for what is to our knowledge the first time. The propagation of spatially fully coherent nonparaxial beams is treated as a special case of our general result. Application of the result is illustrated with the nonparaxial propagation of partially coherent anisotropic Gaussian-Schell-model beams and TEM11-mode Hermite-Gaussian beams.     

Range of turbulence-negligible propagation of Gaussian Schell-model array beams

For linear Gaussian Schell-model (GSM) array beams, the range of turbulence-negligible propagation, in which all of the spatial and angular spreading and the beam propagation factor increasing due to turbulence can be neglected, has been investigated in detail. It is shown that this range of GSM array beams increases with decreasing turbulent parameter and coherent parameter, and depends on the beam number, the waist width, and the relative beam separation distance. This range of a GSM array beam is larger than that of a coherent Gaussian array beam, and this range of a GSM array beam with a large relative beam separation distance is larger than that of a single GSM beam, implying that a GSM array beam may be more appropriate to be used in atmospheric optical communication links than a coherent Gaussian array beam or a GSM beam.     

部分空间相干光束在非Kolmogorov湍流大气中的有效曲率半径

激光在湍流大气中的传输有重要的理论研究和实际应用意义.以高斯-谢尔模型(GSM)光束作为部分空间相干光的典型例,基于非Kolmogorov谱和广义惠更斯-菲涅耳原理, 推导出GSM光束在非Kolmogorov湍流中的有效曲率半径的解析表达式. 重点研究了湍流参数(包括广义指数α,内尺度l₀,和外尺度L₀) 和传输距离z分别对GSM光束有效曲率半径的影响.结果表明, 有效曲率半径R_x(z)随α和z增加先减小然后再增大, 随L₀的减小而增大(3.6<α< 4),随l₀的增加而增大.并对结果做了物理解释.     

部分相干矩形阵列光束在自由空间中的谱移

根据广义惠更斯-菲涅尔衍射积分方法,推导出按矩形方式排布的部分相干高斯-谢尔模型阵列光束的光谱传输公式,定量分析了部分相干高斯-谢尔模型阵列光束在自由空间传输时轴上和离轴相对谱移的变化,并详细讨论了阵列参数和子光束的空间相干参数对相对谱移的影响。结果表明,部分相干高斯-谢尔模型阵列光束通过自由空间传输后,其相对谱移与光源处的谱密度、子光束的空间相干参数以及子光束数目和子光束间距等阵列参数有关,其中,阵列参数对相对谱移的影响非常显著。     

部分相干双曲余弦-高斯光束的传输特性和空间整形

 通过加入高斯项的空间相干度，引入部分相干双曲余弦-高斯（ChG）光束，推导出部分相干ChG光束通过近轴ABCD光学系统传输的解析表达式，并用以研究其传输特性和空间整形。结果表明，部分相干ChG光束的光强分布不能保持传输不变性，其光强分布不仅与传输距离和离心参数有关，而且还与空间相干参数有关。在传输距离固定时，适当改变部分相干ChG 光束的离心参数和空间相干参数，可实现光束的空间整形。光束质量因子随空间相干性的增大和离心参数的减小而减小。高斯-谢尔模型光束和完全相干ChG光束可作为部分相干ChG光束的特例处理。     

非傍轴矢量异常空心光束的传输特性

 将Cai提出的异常空心光束的理论模型推广到非傍轴范畴,推导出非傍轴矢量异常空心光束传输的解析表达式,用以研究它在自由空间中的传输特性。研究表明,异常空心光束在传输过程中光束形状会发生变化。与高斯光束不同,非傍轴异常空心光束傍轴近似成立条件依赖于传输距离,这与异常空心光束光强分布随传输距离的变化有关。非傍轴异常空心光束远场的光束质量可用桶中功率来描述,桶中功率随f参数(波长与束腰宽度的比值)的增大而减小。     

Polarization properties of vectorial nonparaxial Gaussian beams in the far field

The polarization properties of vectorial coherent nonparaxial Gaussian beams are studied. It is shown that, when the source of a nonparaxial Gaussian beam is completely polarized, the degree of polarization of the propagation field maintains a constant value of 1. However, when the source is completely unpolarized, the degree of polarization does not maintain a constant value of 0. In the far field, vectorial nonparaxial Gaussian beams can become partially polarized, except on the propagation axis, and are spatially nonuniform across a typical cross section of the beam even though the source field is completely unpolarized.     

Tensor ABCD law for partially coherent twisted anisotropic Gaussian-Schell model beams

A 4 x 4 complex curvature tensor M>(-1) is introduced to describe partially coherent anisotropic Gaussian-Schell model (GSM) beams. An analytical propagation formula for the cross-spectral density of partially coherent anisotropic GSM beams is derived. The propagation law of M(-1) that is also derived may be called partially coherent tensor ABCD law. The analytical formulas presented here are useful in treating the propagation and transformation of partially coherent anisotropic GSM beams, which include previous results for completely coherent Gaussian beams as special cases.     

Characteristics of a partially coherent Gaussian Schell-model beam propagating in slanted atmospheric turbulence

On the basis of the extended Huygens-Fresnel principle and the model of the refractive-index structure constant in the atmospheric turbulence proposed by the International Telecommunication Union-Radio Communication Sector,the characteristics of the partially coherent Gaussian Schell-model(GSM) beams propagating in slanted atmospheric turbulence are studied.Using the cross-spectral density function(CSDF),we derive the expressions for the effective beam radius,the spreading angle,and the average intensity.The variance of the angle-of-arrival fluctuation and the wander effect of the GSM beam in the turbulence are calculated numerically.The influences of the coherence degree,the propagation distance,the propagation height,and the waist radius on the propagation characteristics of the partially coherent beams are discussed and compared with those of the fully coherent Gaussian beams.     

Partially coherent nonparaxial modified Bessel--Gauss beams

The concept of partially coherent nonparaxial modified Bessel--Gauss (MBG) beams is proposed. Based on the generalized Rayleigh-Sommerfeld diffraction integral, the analytical propagation equations of nonparaxial MBG beams in free space are derived and analysed, and some special cases are discussed. In particular, under the paraxial approximation our results reduce to the corresponding paraxial ones. Numerical calculation examples are given to illustrate the dependence of intensity and spectral degree of coherence on the beam order $m$, \textit{$\xi $} and $f$ parameters, and to compare the difference between the paraxial and nonparaxial results.     

直流固态继电器电磁脉冲失效模式实验研究

采用电流注入法对某型直流固态继电器输入端与输出端的电磁脉冲损伤机制及失效模式进行了实验研究,结果表明:输入端注入电磁脉冲信号时,输出端会产生误动作,并可造成输入电路中三极管BE节产生短路损伤,导致输入端施加控制信号时输出端无法导通;输出端注入电磁脉冲信号时,可造成输出电路中MOSFET管的栅极和漏极产生短路损伤,导致输出端短路。     

Partially coherent nonparaxial Hermite-Gaussian beams and their propagation properties

The concept of partially coherent nonparaxial Hermite-Gaussian (HG) beams is proposed. By using the generalized Rayleigh-Sommerfeld diffraction integral, the closed-form propagation equations of partially coherent nonparaxial HG beams in free space are derived. The on-axis intensity, far-field and paraxial expressions, and specifically, the free-space propagation equations of partially coherent nonparaxial Gaussian Schell-model beams are given, and treated as special cases of our results. It is found that the f and f_σ parameters play a crucial role in determining the nonparaxiality of partially coherent TEM_mn-mode HG beams. Only if the f and f_σ parameters are small enough, the paraxial approximation is applicable.     

Partially coherent beam and its applications

The recent progresses on the propagation, generation and application of partially coherent beam (PCB) are reviewed in this paper. A new tensor ABCD law for treating the propagation of partially coherent Gaussian-Schell model (GSM) beams through a paraxial optical system is derived. The focusing, spectral shift and fractional Fourier transform of the GSM beam are investigated by using the tensor method. The generation of PCB with special optical resonator is studied both theoretically and experimentally. Furthermore, the ghost imaging and superluminal propagation of the PCB is discussed. The results show clearly that the coherence of light have strong influences on the ghost imaging and superluminal propagation.      

Propagation of a twisted anisotropic Gaussian Schell-model beam beyond the paraxial approximation

With the help of a tensor method, an analytical nonparaxial propagation formula for a twisted anisotropic Gaussian Schell-model (GSM) beam in free space is derived based on the generalized Raleigh-Sommerfeld diffraction integral. The far-field nonparaxial propagation expression for a twisted anisotropic GSM beam is also derived. The paraxial approximation is dealt with as a special case of our general result. Our numerical results show that the nonparaxial propagation properties of a twisted anisotropic GSM beam are closely related to the initial beam parameters (i.e., twist factor, transverse spot width matrix, coherence width matrix and wavelength) and the propagation distance. Our formulae provide a convenient and powerful way for studying the paraxial and nonparaxial propagation of an isotropic or anisotropic GSM beam with or without twist phase in free space.