Generation of localized hollow beam based on Bi-nonlinear ZnSe crystals

A new scheme to generate localized hollow beam (LHB) reshaped by Gaussian beam with bi-nonlincar ZnSe crystals is proposed. According to Huygens-Fresnel diffraction theory, the intensity distribution and dark-spot size of generated LHB in the conditions of ZnSe crystals with different thicknesses and Gaussian beams with different waist radii arc calculated. The results show that the intensity distribution shape of LHB is a hollow ellipsoid, and the two-dimensional intensity in the propagation direction shows symmetrical distribution along the center. The aspect ratio of dark spot of generated LHB is obtained by numerical calculation, and it is found that the aspect ratio increases linearly with the increase of waist radius of the incident Gaussian beam. The parameters of generated LHB can be adjusted flexibly, and the generated LHB can be applied to the optical non-contact trapping and the manipulation of atoms and molecules, biomolecules as well as insulating particles with larger size.