共查询到20条相似文献,搜索用时 31 毫秒
1.
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。 相似文献
2.
By using the generalized vectorial Rayleigh-Sommerfeld diffraction integral, the analytical expression for the spectral degree of polarization (SDP) of stochastic spatially and spectrally partially coherent electromagnetic pulsed beams (SSSPCEPB) is derived, and used to study the changes in the SDP of SSSPCEPB in the nonparaxial regime. Similar to that of continuous beams, the f parameter and fαα parameter of pulsed beams also play an important role in determining the nonparaxiality of SSSPCEPB. However, the pulse duration and temporal coherence length of the pulse can change the nonparaxiality of SSSPCEPB. The dependence of SDP on the f parameter, pulse duration and temporal coherence length is emphasized and illustrated numerically. 相似文献
3.
C. L. Ding L. Z. Pan B. Lü 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2010,59(2):329-336
Taking the stochastic electromagnetic J
0-correlated Schell-model pulsed
(JSMP) beam as a typical example of stochastic spatially and spectrally
partially coherent electromagnetic pulsed beams, the analytical expressions
for the cross-spectral density matrix, spectral density, spectral degree of
polarization and spectral degree of coherence of stochastic electromagnetic
JSMP beams propagating in free space are derived, and used to study the
changes in the spectrum, polarization, and coherence of stochastic spatially
and spectrally partially coherent electromagnetic JSMP beams. It is shown
that the on-axis spectrum is blue-shifted in free-space propagation and is
dependent on the pulse temporal coherence length and spatial correlation
parameter. The distribution of the on-axis spectral degree of polarization
depends on the frequency and spatial correlation parameter. The spectral
degree of coherence increases with increasing pulse temporal coherence
length. The results derived are interpreted physically. 相似文献
4.
The analytical expressions for the spectral degree of coherence and spectral intensity of spatially and spectrally partially coherent cosh-Gaussian pulsed (ChGP) beams propagating in free space are derived. It is shown that the spectral degree of coherence and spectral intensity of spatially and spectrally partially coherent ChGP beams depend on the spatial correlation parameter, decentered parameter and temporal coherence length. Depending on the decentered parameter, the effective width of the spectral degree of coherence can be larger than, smaller than or equal to that of the spectral intensity. The results are illustrated by numerical examples. 相似文献
5.
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 fσ 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. 相似文献
6.
7.
Dongbing Liu 《Optics Communications》2010,283(3):379-385
The analytical expression for the spectrum of spatially and spectrally partially coherent cosh-Gaussian pulsed (ChGP) beams focused by an aperture lens is derived and used to study their spectral properties at the focal plane and on the axis. The effect of the truncation parameter, spatial correlation parameter, decentered parameter and temporal coherence length on the spectral shifts and spectral switches of spatially and spectrally partially coherent ChGP beams is stressed. The results are illustrated numerically and interpreted physically. 相似文献
8.
部分相干双曲余弦-高斯光束的传输特性和空间整形 总被引:1,自引:0,他引:1
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。 相似文献
9.
10.
The concept of the degree of cross-polarization is extended from stochastic electromagnetic stationary beams to stochastic electromagnetic pulsed beams, and the propagation properties of the degree of cross-polarization of stochastic spatially and spectrally partially coherent electromagnetic pulsed beams is studied. The influence of pulse duration and temporal coherence length on the degree of cross-polarization P is emphasized. It is shown that P exhibits an oscillatory behavior in free-space propagation. An increase in the pulse duration or a decrease in the temporal coherence length can weaken the oscillation of P. The validity of the results is interpreted physically. 相似文献
11.
《Optik》2013,124(13):1523-1527
The propagation behavior of the spectral degree of polarization of stochastic spatially and spectrally partially coherent electromagnetic flat-topped pulses in free space is studied. Numerical calculation results are given to illustrate the dependence of spectral degree of polarization on the beam order, pulse frequency, temporal coherence length, pulse duration and spatial correlation length. It is shown that with increasing beam order M the position z of the on-axis spectral degree of polarization P = 0 decreases, and the distribution of spectral degree of polarization is different for different values of M. 相似文献
12.
This paper is based on the unified theory of coherence and polarization of stochastic electromagnetic beams and the extended Huygens–Fresnel principle, combined with the quadratic approximation of Rytov’s phase structure function and the generalized Stokes parameters. We have derived the novel expressions for the cross-spectral density matrix elements and the degree of cross-polarization of a class of elliptically polarized spatially and spectrally partially coherent Electromagnetic Gaussian-Schell model pulse (EGSMP) beams propagating through atmospheric turbulence along a slant path. Additionally, we calculate and analyze the effects of the turbulent intensity, the initial pulse duration, waist width of the beam, the spatial coherence length and temporal coherence length et al. on the polarization properties of fully polarized and partially coherent EGSMP beams. Finally, a comparison of the impact of those factors on the partially polarization beams is made. The results show that the influences of the turbulent intensity, the initial pulse duration, waist width of the beam, the spatial coherence length and temporal coherence length et al. on the polarization properties of fully polarized and partially coherent EGSMP beams are larger. While the effects of those parameters on the partially polarization and partially coherent EGSMP beams are smaller. It is noted that the results of this paper have established sound theoretical basis on the topic of improving performance of the laser system propagating through the atmospheric turbulence. 相似文献
13.
Starting from the Rayleigh–Sommerfeld diffraction integral, the closed-form expressions for the near- and far-field power spectra of diffracted pulsed cosh-Gaussian (ChG) beams propagating in dispersive media are derived, and the anomalous behavior of the far-field spectrum of diffracted pulsed ChG beams in dispersive media is studied. It is shown that near the phase singularities, the spectral switch may take place. The truncation parameter, decentered parameter and pulse duration of pulsed ChG beams and the dispersive property of the medium affect the behavior of the spectral switch of pulsed ChG beams. 相似文献
14.
Taking the partially coherent cosh-Gaussian (ChG) vortex beam as an illustrative example, the composite spectral Stokes singularities formed by coherent and incoherent superpositions of partially coherent vortex beams beyond the paraxial approximation are studied, where the effect of superposition scheme on composite spectral Stokes singularities is stressed. It is shown that there exist s12 (C-points), s23 and s31 composite spectral Stokes singularities, which are variable by varying a control parameter, such as the spatial correlation length, waist width, off-axis distance, or decentered parameter, as well as the propagation distance. In particular, the number, position, degree of polarization of composite spectral Stokes singularities and the critical point at which the creation–annihilation process takes place depend on the superposition scheme. A comparison with the previous work is also made. 相似文献
15.
矢量非傍轴双曲余弦-高斯光束 总被引:3,自引:3,他引:0
引入了矢量非傍轴双曲余弦-高斯(ChG)光束概念。使用矢量瑞利-索末菲衍射积分公式推导出了矢量非傍轴ChG光束在自由空间传输的解析公式。矢量非傍轴ChG光束轴上和远场的解析式以及傍轴结果作为一般传输公式的特例给出。研究表明,对矢量非傍轴ChG光束,其非傍轴性主要由f参数决定,但偏心参数会影响其横向光强剖面形状和非傍轴行为。 相似文献
16.
Taking the Gaussian Schell-model pulsed (GSMP) beam as a typical example of spatially and spectrally partially coherent pulsed beams, an analytical expression for the far-field spectrum of diffracted GSMP beams in Young’s interference experiment is derived, and used to study the spectral shifts and spectral switches of GSMP beams in the far field. Numerical calculation results are given to illustrate the dependence of spectral shifts and spectral switches on the obscuration ratio ε, temporal coherent length Tc, spatial correlation parameter β and diffraction angle α. It is shown that the critical angle αc of the first- and second-order spectral switches moves away from the z axis with increasing Tc, but αc of the third-order spectral switch moves towards the z axis with increasing Tc. The spectral transition height Δ decreases and spectral minimum Smin increases as Tc increases. αc decreases, Δ increases and Smin decreases as β increases. The potential application of spectral switches of spatially and spectrally partially coherent pulsed beams in information encoding and transmission is proposed. 相似文献
17.
Can two partially coherent cosh-Gaussian beams generate far fields with the same spectral degree of coherence? 下载免费PDF全文
Taking partially coherent cosh--Gaussian (ChG) beams as an example
of more general partially coherent beams, we have studied the
spectral degree of coherence of partially coherent ChG beams in the
far field. It is shown that, unlike Gaussian Schell-model (GSM)
beams, in the strict sense there do not exist two partially coherent
ChG beams which can generate far fields with the same spectral
degree of coherence. However, under certain conditions it is
possible to find two partially coherent ChG beams with the same
spectral degree of coherence in the far field. 相似文献
18.
对部分空间和部分光谱相干2维高斯-谢尔模型脉冲光束在自由空间传输的光谱和时间特性做了详细的数值研究。结果表明,部分空间和部分光谱相干高斯-谢尔模型脉冲光束在自由空间传输中发生了光谱移动,光谱移动与场点位置、空间相关长度和时间相干长度有关。在轴上,光谱出现蓝移,相对光谱移动随传输距离的增加而增大,随空间相关长度和时间相干长度的增加而减小,并逐渐趋于一定值。在轴外,光谱出现蓝移和红移,并与空间相关长度和时间相干长度有关。脉冲时间波形不变,对所得主要结果做了物理解释。 相似文献
19.
20.
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 fσ parameters play a crucial role in determining the nonparaxiality of partially coherent TEMmn-mode HG beams. Only if the f and fσ parameters are small enough, the paraxial approximation is applicable. 相似文献