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Taking phase error, turbulent atmosphere, jitter, vacancy factor and tilt error into consideration, we propose a general propagation formula for both coherent and incoherent combined beams with different kinds of aberrations. Comparative study on the propagation performance of coherent and incoherent combined beams is presented. Beam propagation factor (BPF) defined as laser output power in a specified far-field bucket divided by the total output power radiating from the effective near-field exit aperture of the laser beam is introduced as the beam quality factor to give a quantitative study. It is revealed that the coherent combined beam has great advantage when propagating in free-space compared with the incoherent combined beams. However, the coherent combined beam is more sensitive to the environmental aberrations, and the beam quality degrades faster with an increase in the aberrations’ intensity. Scintillation index as the high moments of the combined intensity field is also studied. It is revealed that both coherent and incoherent combined beams exhibit less scintillations compared with a single-aperture beam, and the incoherent combined beam demonstrates better scintillations reducing the performance. Our methodology offers an all-round performance evaluation on the two kinds of laser systems. 相似文献
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基于Braunstein与Kimble的连续变量量子隐形传态方案,通过调节输出端位移因子可以优化单模压缩相干态和单模压缩真空态量子隐形传态的保真度;分析了单模压缩态的压缩参数对保真度的影响。 相似文献
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We present the numerical results of the photorefractive two-wave mixing in the presence of an incoherent beam by considering
the influence of the ratios of the intensities and the light-excitation cross sections of the incoherent beam to the coherent
beams on the space-charge field and the effective coupling coefficient. The results show that the incoherent beam can control
the intensity of the coherent beams effectively. The experimental results agree with the theory well. One application is demonstrated
to obtain the positive and negative coherent replicas of an incoherent image. The coherent images have a resolution of 80.6 line
pairs/mm.
Received: 2 March 1999 / Revised version: 26 July 1999 / Published online: 20 October 1999 相似文献
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ZHANG Liangmin ZHANG Jingwen SHAO Zongshu MU Xiaodong CHEN Huanchu JIANG Minhua 《Chinese Journal of Lasers》1996,5(6):526-534
MechanismforPhaseConjugationReflectionsofTwoMutuallyCoherentBeamsfromPotassiumSodiumStrontiumBariumNiobate¥ZHANGLiangmin;ZHAN... 相似文献
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基于高斯谢尔光束的相干模式分解理论和波动光学,建立了部分相干同步辐射硬X射线光束通过光学器件的传播模型。模拟了微聚焦X射线光束照射下光栅的分数塔尔博特效应,得到了聚焦光束的光强分布和相干特性变化,并分析了散焦光束入射下的光栅自成像。然后通过模拟准直光束入射下的光栅塔尔博特效应,得到了不同传播距离处自成像条纹的变化情况,分析了影响光栅自成像条纹形状的因素。通过光栅衍射条纹测量同步辐射相干度,发现对矩形相位光栅来说,应该对衍射图样进行傅里叶分解,求出各级傅里叶系数随传播距离的变化曲线,从而得到入射光束相干特性。 相似文献
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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
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Wenbo Du Xiaolin Wang Yanxing Ma Jiajian Zhu Xiaolin Dong Pu Zhou Xiaojun Xu Bohong Shu 《Optics & Laser Technology》2012,44(1):247-250
Seeding high power fiber amplifier employing multi-tone fiber laser is an effective approach to suppress stimulated Brillouin scattering (SBS). In this paper, a two-stage 1064 nm high power fiber amplification system was set up. Single-, two- and three-tone fiber lasers were employed. SBS threshold powers and maximum output powers of the multi-tone cases are enhanced compared with the single-tone case. The multi-tone amplifiers also show comparable optical-to-optical efficiency to the single-tone amplifier. To demonstrate and validate coherence property of the two multi-tone fiber amplifiers, the output laser beams of the amplifiers were self-interfered in our self-made coherent beam combining system. The laser beams of the multi-tone cases showed good coherence property comparable to the single-tone case, which implied that the high power output laser light of the multi-tone fiber amplifiers could be used for coherent beam combining. 相似文献
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In view of second-order coherence theory, the generalized diffractive axicon illuminated by partially coherent Gaussian Schell-model (GSM) beams is analyzed. An analytical equation for focal depth of axicon without aperture illuminated by spatial partially coherent GSM beam is derived. We showed that the off-axis images can be evaluated by using the method of stationary phase at any correlation state, hence we demonstrated that the intensity distribution of diffracted beam is a superposition of Bessel Beams of various orders. We also showed that the diffracted beam is nondiffractive only on the boundaries of the focal depth. 相似文献
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Suye Lü 《Optics Communications》2007,279(1):150-158
Based on the theory of optical coherence, the spatial coherence properties and directionality of partially coherent cosh-Gaussian (ChG) beams are studied. It is shown that unlike Gaussian Schell-model (GSM) beams, in the strict sense there do not exist partially coherent ChG beams which may produce the same far-field radiant intensity distribution as a fully coherent laser beam. However, under certain conditions it is possible to find partially coherent ChG beams with the same far-field radiant intensity distribution as a fully coherent laser beam. 相似文献
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Xiaoqing Li 《Optics Communications》2009,282(1):7-1239
The influence of atmospheric turbulence on the propagation of superimposed partially coherent Hermite-Gaussian (H-G) beams is studied in detail. The closed-form propagation equation of superimposed partially coherent H-G beams through atmospheric turbulence is derived. It is shown that the turbulence accelerates the evolution of three stages which superimposed partially coherent H-G beams undergo. The turbulence results in a beam spreading and a decrease of the maximum intensity. However, the larger the beam number M, the beam order m, the separate distance xd, and the smaller the beam correlation length σ0 are, the less the power focusability of superimposed partially coherent H-G beams is affected by the turbulence. Specially, superimposed partially coherent H-G beams are less sensitive to turbulence than superimposed fully ones, and than partially coherent H-G beams if the beam power focusability and the maximum intensity are taken as beam criterions. However, the maximum intensity of superimposed partially coherent H-G beams is less sensitive or more sensitive to turbulence than that of superimposed Gaussian Schell-model (GSM) beams depending on σ0. 相似文献
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相较于相干光束,部分相干光束经过湍流大气传输能够有效地抑制湍流引起的光束展宽、光斑漂移及光强闪烁等扰动效应,在自由空间光通信、激光雷达和激光遥感等方面有重要的应用前景.近年来,部分相干光束湍流大气传输研究受到越来越多学者的关注.本文回顾了部分相干光束在湍流大气中传输特性研究的发展历程、理论基础及常用的理论方法,介绍了处理光束经过湍流大气传输的相位屏数值模拟方法,以及如何把该方法运用到处理部分相干光束传输. 相似文献
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Numerical Simulation for Coherent and Partially Coherent Beam Propagation through Atmospheric Turbulence 下载免费PDF全文
Propagation properties of coherent and partially coherent beams in atmospheric turbulence are investigated respectively by using numerical simulation It is found that a partially coherent beam has a spreading larger than a coherent beam. However, from the point view of relative beam spreading and intensity scintillation, a partially coherent beam is less affected than the corresponding coherent beam, which may be the most important virtue of partially coherent beams that could be utilized to improve the performance of laser engineering. The beam wandering is almost independent of the degree of the source coherence. More aperture averaging occurs when beam becomes more coherent. 相似文献
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Guoquan Zhou 《Optics & Laser Technology》2010,42(3):489-1064
Based on the method of truncated second-order moments, the analytical expressions of the generalized beam propagation factor for truncated partially coherent cosine-Gaussian and cosh-Gaussian beams are derived. The beam propagation factors of the truncated partially coherent cosine-Gaussian and cosh-Gaussian beams depend on the acentric parameter, the truncation parameter, and the coherent parameter. According to the derived expressions, the beam propagation factors are illustrated and analyzed with numerical examples, and the influences of the different parameters on the beam propagation factors are also discussed in detail. 相似文献
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考虑原子间偶极相互作用,求出好腔中的Bell态原子与纠缠相干态光场相互作用系统的保真度。结果表明,对于理想腔,若原子初始时刻处于相干保持态,系统保真度始终等于1;若原子初始时刻处于其余Bell态之一,腔场初态的平均光子数很小,系统保真度在0~1之间作周期性振荡,随着腔场初态的平均光子数的增加,系统保真度的振荡频率增大,振幅减小。对于好腔,若原子初始时刻处于相干保持态,系统保真度呈指数单调衰减;若原子初始时刻处于其余Bell态之一,系统保真度呈指数振荡衰减,且随着腔场初态的平均光子数的增加,系统保真度的振荡频率增大,振幅减小。 相似文献
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好腔中的Bell态原子与纠缠相干态光场相互作用系统的保真度 总被引:2,自引:2,他引:0
考虑原子间偶极相互作用,求出好腔中的Bell态原子与纠缠相干态光场相互作用系统的保真度.结果表明,对于理想腔,若原子初始时刻处于相干保持态,系统保真度始终等于1;若原子初始时刻处于其余Bell态之一.腔场初态的平均光子数很小,系统保真度在0~1之间作周期性振荡,随着腔场初态的平均光子数的增加,系统保真度的振荡频率增大,振幅减小.对于好腔,若原子初始时刻处于相干保持态,系统保真度呈指数单调衰减;若原子初始时刻处于其余Bell态之一,系统保真度呈指数振荡衰减,且随着腔场初态的平均光子数的增加,系统保真度的振荡频率增大,振幅减小. 相似文献
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Suye Lü 《Optics Communications》2008,281(13):3514-3521
Taking the partially coherent cosh-Gaussian beam (ChG) as an illustrative example, the far-field divergence angle and directionality of partially coherent beams are studied. There are three competing physical mechanisms, i.e., the spatial coherence, diffraction and decentration, which affect the far-field divergence angle of partially coherent ChG beams. Two partially coherent ChG beams may generate the same far-field divergence angle, and partially coherent ChG beams may also have the same far-field divergence angle as a fully coherent ChG beam or as a fully coherent Gaussian laser beam if the three physical mechanisms are appropriately balanced. The consistency of the directionality of partially coherent beams expressed in terms of the far-field divergence angle and in terms of the far-field radiant intensity distribution is examined. Generally, two partially coherent beams with the same far-field divergence angle have not certainly the same far-field radiant intensity distribution. However, under certain conditions, it is possible to achieve the consistency of the directionality expressed in terms of the far-field divergence angle and of the normalized far-field radiant intensity distribution. 相似文献
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