Abstract 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 $\beta$, amplitude ratio $\eta$, waist width ratio $\xi$, or off-axis distance ratio $\mu$. The net topological charge lnet is not always equal to the sum lsum 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.
Received: 03 July 2007
Revised: 09 September 2007
Accepted manuscript online:
PACS:
42.25.-p
(Wave optics)
Fund: Project supported by
the National Natural Science Foundation of China (Grant
No 10574097).
Cite this article:
Cheng Ke(程科), Liu Pu-Sheng(刘普生), and Lü Bai-Da(吕百达) Composite optical vortices in noncollinear Laguerre--Gaussian beams and their propagation in free space 2008 Chin. Phys. B 17 1743
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