Shaping autofocusing Airy beams through the modification of Fourier spectrum.

A new type of Airy beam arisen from the modification of Fourier spectrum is introduced numerically and experimentally. The autofocusing Airy beam (AAB) exhibits the features of off-axis autofocusing and transverse self-accelerating, producing a needle-like focus in the longitudinal direction and a tiny focal spot at the focusing plane. Furthermore, the focusing properties such as focusing position, focal spot size, focusing intensity and depth of focus can be adjusted by modulating parameters of the AAB. Experimental demonstrations of particle trapping and manipulation with the AAB are also presented. The number of trapped particles can be controlled by changing the focal spot size at the autofocusing plane. Our results offer practical applications in particle manipulation, fluorescent imaging technology, laser spectroscopy and so on.