Enhanced abrupt autofocusing and depth-of-focus of circular Airy derivative beams via controlled asymmetry

We demonstrate enhanced abrupt autofocusing and depth-of-focus (DOF) in circular Airy derivative beams through controlled asymmetry. The controlled asymmetry enables multiple discrete autofocusing events to merge into a single continuous elongated focal region with improved energy confinement, thereby enhancing both the abrupt autofocusing and the DOF. The DOF is extended by up to 400% with a 32% improvement in abrupt autofocusing and a ∼32 μm focal spot size, whereas the abrupt autofocusing can be further enhanced by up to 193% with a ∼56 μm focal spot size while maintaining nearly the same DOF. This reveals a trade-off between the DOF and abrupt autofocusing ability. Experimental results show good agreement with numerical simulations. The resulting asymmetric circular Airy derivative beams, combining strong abrupt autofocusing with extreme DOF, offer promising applications in optical trapping, optical communications, microfabrication, and biomedical imaging.