Abruptly autofocusing property of blocked circular Airy beams.

We theoretically and experimentally study the propagation characteristics of the circular Airy beam (CAB) when its first few light rings are blocked. It is shown that the focus position of the blocked CAB will remain the same, and its abruptly autofocusing property will be enhanced. Since the maximum focal intensity almost remains the same when the first ring is blocked, a better result of abruptly autofocusing property can be obtained when only the first ring is eliminated. Compared with the common CAB with a same hollow region, the intensity of the blocked CAB will focus at a different position and the intensity will be increased much larger than the common CAB.