No abstract

Two-dimensional periodic microstructures, including both microholes and micro-orbicular platforms, have been fabricated on the surface of silica glass by a single shot of three interfered femtosecond laser pulses. The three-dimensional structure of a fabricated hexagonal lattice can be revealed by atomic force microscopy. The formation of the microstructure and the dynamic process of the interaction between the femtosecond laser and the silica glass have been discussed.

The rotational motions of the optically trapped microscopic particles by the vortex femtosecond laser beam are investigated in this paper. Black particles can be trapped and rotated by a vortex femtosecond laser beam very effectively because the vortex beam carries orbital angular momentum due to the helical wave-front structure in assoication with the central phase singularity. Trapped black particles rotate in the vortex beam due to the absorption of the angular momentum transferred from the vortex beam. The rotating directions of the trapped particles can be modulated by reversing the topological charge of the optical vortex in the vortex femtosecond beam. And the rotating speeds of the trapped microscopic particles greatly depend on the topological charges of the vortex tweezer and the used pulse energies.

When linearly polarized light illuminates a plasmonic lens, it is challenging to realize centrally symmetric focal spot in the near field since there is mismatch between the symmetries of the plasmonic structures and the polarization spatial distribution of the incident light. In this paper, we propose a plasmonic lens that can focus surface plasmon to a centrally symmetric field when illuminated by light with linear polarization. Remarkably, the intensity distribution of the focal field is insensitive to the polarization direction, which makes it more reliable in optical applications. Numerical simulations are used to check the performance of the proposed structure. Comparisons with two conventional plasmonic lenses are made to demonstrate its unique superiority in polarization-insensitive focusing.