Tunable autofocusing and optical trapping with symmetric butterfly Gaussian beams
Phys. Rev. A 111, 063516 – Published 18 June, 2025
DOI: https://doi.org/10.1103/tfs1-gy3h
Abstract
We propose an autofocusing beam, named the symmetric butterfly Gaussian beam (SBGB). Its analytical expression in free space is derived, and its transmission characteristics are systematically analyzed. Compared to the symmetric Airy Gaussian beam and symmetric Pearcey Gaussian beam, the SBGB exhibits superior abruptly autofocusing capabilities and enhanced particle trapping abilities. By adjusting the distribution factors, the SBGB can generate a bifocal structure. Interestingly, introducing a second-order chirp factor enables the two focal spots to evolve into orthogonal needlelike structures. The focal size, focal position, and intensity of the SBGB can be flexibly adjusted by tuning the second-order chirp factor. Moreover, we theoretically analyze the trapping properties of the SBGB and explore the trapping force distributions in its focal regions. Experimental results verify that the dual needlelike focal points can stably trap and manipulate multiple silica particles. With outstanding autofocusing performance and unique focal structures, the SBGB holds great potential for applications in optical manipulation, biomedical research, and laser processing.
