利用部分相干效应获得局域空心光束

Generation of Partially Coherent Bottle Beam with Variable Size by Partially Coherent Effect

研究一种特殊的部分相干光束经透镜聚焦后,在几何焦点附近的三维光强分布.结果表明,几何焦点附近的聚焦光强分布不仅依赖于入射部分相干光的光强分布,还依赖于入射光的空间相干度.据此,可以通过选择合适的空间相干度,产生部分相干局域空心光束.此外,还研究入射部分相干光束的相干度和菲涅耳数对局域空心光束的影响.结果显示,对于相干度一定的部分相干光束,当菲涅耳数小到一定程度时,部分相干局域空心光束的现象将消失.

In this paper, we have investigated a particular class of partially coherent beam focused by a lens. The three-dimensional intensity distribution near geometrical focus is investigatcd. It is shown that the focused intensity distribution near the geometrical focus is dependent not only on the intensity distribution of the incident partially coherent beam, but also on the degree of coherence. A partially cohercnt bottle beam can be generated by choosing appropriate degree of spatial coherence. The influence of the Fresnel number and the dcgree of coherence of the incident partially coherent beam on thc partially cohercnt beam is studied. We find that, for a ccrtain dcgrec of spatial coherence, the partially coherent bottle beam disappcars if the Fresnel number is too small.