共查询到11条相似文献,搜索用时 0 毫秒
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衍射扭曲高斯-谢尔模型光束在远场的光谱移动和光谱开关 总被引:1,自引:0,他引:1
从部分相干光的传输理论出发,研究了被光阑衍射扭曲高斯-谢尔模型光束远场的光谱变化规律。结果表明,扭曲高斯-谢尔模型光束在远场也会出现光谱移动和光谱开关效应。与衍射高斯-谢尔模型光束情况相比,光谱移动和光谱开关效应不仅与光束空间相关性、截断参量和源光谱谱宽有关,光束的扭曲因子也会对衍射扭曲高斯-谢尔模型光束远场的光谱移动和光谱开关效应产生影响。通过数值计算结果详细讨论了光束扭曲因子影响衍射扭曲高斯-谢尔模型远场光谱的规律。 相似文献
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大气湍流对斜程传输准单色高斯-谢尔光束时间相干性的影响 总被引:1,自引:1,他引:1
由第一类零阶贝塞尔函数的级数展开推导出波结构函数在任意湍流条件下的近似表达式。由广义惠更斯-菲涅耳原理、随高度变化的Hufnagel-Valley湍流廓线模型以及波结构函数在任意湍流条件下的近似表达式,导出了斜程传输时准单色高斯-谢尔光束互相干函数的解析式。然后,利用表征光束时间相干性的纵向相干长度(可由互相干函数导出),研究了斜程传输时大气湍流对准单色高斯-谢尔光束时间相干性的影响。研究结果表明,准单色高斯-谢尔光束的时间相干性在整个斜程传输过程中保持不变。最后,对该结果在物理上给予了定性解释。 相似文献
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The analytic design of anamorphic optical system for transforming the coherent Gaussian beam of a He–Ne laser to a partially coherent Gaussian Schell-model beam with an anisotropic cross-section and an anisotropic degree of coherence is described. Design equations are formulated and some design examples are presented. 相似文献
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This paper presents a quantum mechanical formalism of the classical coherence theory, within which the generalized radiance function defined in the time domain is regarded as a phase space representative of a time-dependent correlation operator of a polychromatic field. The theory deals with both stationary and nonstationary fields and, for a stationary field, provides a new operator formalism of the usual theory of optical coherence developed in the space-frequency domain. New results include an operator representation of the mutual coherence function, an operator version of the Wiener-Khintchine theorem, and an operator theorem that projects the correlation operator of a polychromatic field onto a particular spectral component. As illustrative examples, the previous formulas regarding the relationship between temporal coherence and spatial coherence, and the relationship between spectral properties and coherence properties are derived from the new operator formulas. The correspondence of the present formalism to the usual formalism using Dirac notation to describe the propagation of a stationary, partially coherent, quasi-monochromatic field is also considered. 相似文献
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The problem of the approximation of the HE11 radiation pattern by a Gaussian distribution is discussed. A numerical comparison between the HE11 far-field theoretical pattern, and the Gaussian approximations derived by Abrams and by Crenn, permits and evaluation of the precision of these approximations. A new optimized HE11 Gaussian approximation is calculated: the value of ro=0.421a (or wo=0.596a) for the beam radius at the waist is demonstrated to give the best HE11 Gaussian approximation in the far-field and is very close to the result given by Crenn, while the Abrams value is less precise. The calculations are extended to the near-field. Universal curves for intensity, amplitude and power distribution are given for the HE11 radiated mode. These results are of interest for laser waveguide applications and for plasma ECRH transmission systems. 相似文献
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运用三维时域有限差分法,研究了完美/缺陷光子晶体特定参量的改变对发光二极管光抽取效率影响,得出优化参量.基于近场远场转换,进一步分析了两种不同类型的缺陷引入及其周边空气孔半径的改变对光子晶体发光二极管远场辐射特性的影响.数值研究的结果表明,通过引入缺陷以及减小缺陷周围空气孔半径能够同时提高光子晶体发光二极管的光抽取效率和远场辐射方向性. 相似文献
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The spatial correlation properties and the spectral intensity distributions of focused Gaussian Schell-model (GSM) array beams are studied in detail. The closed-form expressions for the spectral degree of coherence and the spectral intensity of focused GSM array beams are derived. It is shown that the spectral degree of coherence of focused GSM array beams is the same as that of focused GSM beams in the focal plane. On the other hand, it is found that, in the focal plane the spectral intensity distribution of focused GSM array beams is the fringe pattern when the value of the coherence length is small. However, it becomes one peak located at the center as the value of the coherence length is large enough. In the focal plane, the spectral intensity maximum increases and the width of the normalized spectral intensity distribution decreases as the beam number increases. In general, for GSM array beams, the width of the modulus of the spectral degree of coherence in the focal plane always exceeds that of the normalized spectral intensity distribution, which is different from the behavior of focused GSM beams. In addition, the power in the bucket (PIB) and the beam propagation factor (M2 factor) are also discussed. The main results are explained physically. 相似文献