Focusing pattern of axisymmetric Bessel-Gaussian beam with helical polarization under triangular modulation.

Based on the theory of vector diffraction and the principle of triangular modulation, the focusing characteristics and patterns of an axisymmetric Bessel-Gaussian beam with helical polarization with quadratic radial correlation are studied. The results show that both the beam parameters mu and the triangular modulation parameters n can significantly change the intensity distribution of the focusing region. Under the same spiral parameter C, obvious lateral changes of the focusing pattern can be observed by changing either of the above two parameters. The focusing pattern can be changed from focusing ring to two parallel focal spots extending horizontally, and moreover, some parameters have obvious "self-reduction" characteristics, which is of certain significance for the application of Bessel-Gaussian beams in the field of optical micromanipulation. (C) 2020 Optical Society of America