为了研究具有精细结构的圆对称爱里光束的传输特性, 通过减小与光斑宽度相关的参数 w, 使初始光场具有与波长相近的精细结构。在此特定情况下, 用瑞利. 索末菲衍射理论对圆对称爱里光束的传输特性进行数值计算。研究结果表明: 随着参数 w的减小, 圆对称爱里光束的精细结构增加, 使得代表高频成分的离轴光场影响逐渐增大并参与聚焦行为, 焦点光强峰值增大, 焦点主光斑的半高全宽减小, 突然自聚焦能力得到显著提升; 当 w减小到某一阈值后, 由于持续增加的高频分量进入到倏逝波, 焦点光强峰值减小, 焦点主光斑的半高全宽增大, 突然自聚焦性能下降。

The circular Airy beam is a type of autofocusing waves. The unique property of the circular Airy beam is that this beam can maintain quite low intensity profiles before the focal point and the maximum intensity of the beam can abruptly increase by orders of magnitude just at the focal point. The fine structures of the beam can be obtained by decreasing w. In this paper, firstly, the Fresnel, the Fresnel-Kirchhoff and the Rayleigh-Sommerfeld diffraction theories were compared. It found that the Rayleigh-Sommerfeld diffraction theory was the most suitable method. Then, the propagation characteristics of the circular Airy beam with fine structures were studied in detail by using the Rayleigh-Sommerfeld diffraction theory. The results showed that the nonparaxial components of the field would increase as w decreases. At beginning, the increasing nonparaxial components enhanced the autofocus, resulting in an enhancement of the peak intensity and a decreasing of the full width at half-maximum at the focus. However, as w further decrease and beyond a certain value, more and more nonparaxial components became evanescent wave, and could not propagate to far field. The peak intensity at the focus decreased sharply.