Tunable optical bottles and needle-like focuses of elliptical swallowtail beams

In this study, we break away from the conventional circular symmetric framework by proposing the elliptical Swallowtail beam (ESB), whose elliptical symmetry gives rise to a series of distinctive features. Notably, the ESB exhibits spontaneous dual-focusing behavior. Leveraging this property, we demonstrate that simply introducing a second-order chirp factor enables the generation of highly tunable optical bottles with adjustable numbers, lengths, and cross-sectional areas. Furthermore, needle-like focal spots form at the bottle openings, with their size and orientation precisely controllable. Optical tweezers experiments confirm the practical utility of the ESB: the needle-like focuses allow linear manipulation of silica particles, while the optical bottles stably trap mesocarbon particles in air. With its unique intrinsic properties and excellent tunability, the ESB paves the way for the design of advanced optical tweezers and versatile optical manipulation schemes.