摘要
In this paper,an effective method to garner sub-wavelength longitudinally polarized multi-segment optical needle sequence by using a specially designed hybrid filter(HF) in a high numerical aperture(NA) objective focusing system is proposed.The HF is coupled by a binary phase transmission function and a multi-segment modulation function,and the binary phase filter is designed by the particle swarm optimization(PSO) algorithm and acts on the radially polarized Bessel Gaussian(RPBG) beam to obtain a longitudinally polarized optical needle with long depth of focus(DOF,6λ) and a sub-wavelength transverse spot size(0.430λ).The optical needle is with high uniformity of 98% and high beam quality of 96%,and the negligible sidelobe is 15%.On this basis,the multi-segment optical needle sequence with tunable spacing or number can be realized by the multi-segment modulation function.It is found that the HF makes the generation of multi-segment optical needle sequence more flexible and reliable.This research has broad application prospects in material processing,particle acceleration,particle capture and other fields.
基金
supported by the ‘111’ Project by the State Administration of Foreign Experts Affairs
the 2020 Mobility Programme of the Sino-German Center for Research Promotion (M-0396)
the Ministry of Education of China (No.B07014)
the National Natural Science Foundation of China (Nos.11974258 and 11604236)
the Key Research and Development (R&D) Projects of Shanxi Province (No.201903D121127)。
