以径向偏振圆对称Airy光束为例,基于Rayleigh-Sommerfeld矢量衍射理论,探讨了矢量圆对称Airy光束的传输特性。随着光束波长增大其自聚焦焦距减小,光束等效数值孔径增大。与傍轴理论计算结果比较后发现,当等效数值孔径大于0.09时,傍轴理论不再适用,因为此时傍轴理论低估了光波的衍射效应和矢量性。

In this paper,the vector propagation dynamics of the radially circular Airy beams have been studied based on Rayleigh-Sommerfeld integration.With the increase of the wavelength the focal length of self-focusing will decrease and the equivalent numerical aperture will increase.It is found that the paraxial theory is valid when the equivalent numerical aperture is less than 0.09 by comparing with the calculation results of Rayleigh-Sommerfeld integration.The paraxial theory under estimates the diffraction effect and the vector property of light waves.Thus,paraxial theory can’t be used for tightly focused systems.