%A Cheng Ke, Liu Pu-Sheng, Lü Bai-Da
%T Composite optical vortices in noncollinear Laguerre--Gaussian beams and their propagation in free space
%0 Journal Article
%D 2008
%J Chin. Phys. B
%R 10.1088/1674-1056/17/5/034
%P 1743-1751
%V 17
%N 5
%U {http://cpb.iphy.ac.cn/CN/abstract/article_23129.shtml}
%8 2008-05-20
%X Taking two Laguerre--Gaussian beams with topological charge l=±1 as an example, this paper studies the composite optical vortices
formed by two noncollinear Laguerre--Gaussian beams with different
phases, amplitudes, waist widths, off-axis distances, and their
propagation in free space. It is shown by detailed numerical
illustrative examples that the number and location of composite
vortices at the waist plane are variable by varying the relative
phase β, amplitude ratio η, waist
width ratio \textitζ, or off-axis distance ratio μ. The net topological charge l_{net} is not always equal to
the sum l_{sum} of charges of the two component beams. The
motion, creation and annihilation of composite vortices take place
in the free-space propagation, and the net charge during the
propagation remains unchanged and equals to the net charge at the
waist plane.