Zijing Zhang

The ability to realize autofocusing of optical beams is crucial for numerous applications. However, traditional Gaussian beams suffer from a narrow tunable range of the focal plane, an inhomogeneous intensity distribution, and a propensity to induce photodamage, which degrade their practical performance in optical manipulation. Although various structured beams have been proposed for optical tweezers to mitigate photodamage, their focal intensity distributions still exhibit insufficient tunability and uniformity. In this work, elliptical Butterfly beams (EBBs), the optical fields characterized by unique dual-focusing property, are introduced and experimentally demonstrated. We incorporate a cross-phase modulation and second order chirp factor to achieve flexible transformation between one and four needle like focal points. Notably, the EBBs are able to rotate the needle like focuses without altering the overall intensity. Furthermore, the homogeneity, intensity and length of their needle like focal points are all tunable. Experimental results demonstrate that the four needle like focal points can achieve stable manipulation of multiple silica particles. With their distinctive focusing properties, the EBBs provide enhanced optical capabilities for use in particle capture and biomedical applications.