Multifocus autofocusing Airy beam.

We propose a multifocus autofocusing Airy beam (MAAB) by modifying the frequency spectrum of a symmetric Airy beam (SAB) with a Gaussian band elimination filter. Unlike the original SAB, there are four off-axis foci at the autofocusing plane of the MAAB. The MAAB has a better abruptly autofocusing property than the original SAB. In addition, with the increase of the normalized intensity at the first peak, the focal position (second peak) of the MAAB remains almost the same, whereas the position of the first peak shifts along the propagation direction gradually. These unique characteristics of MAAB have been demonstrated by experiment and indicate potential applications in various fields.