We propose a method for generating focal beams with special intensity distributions using radially polarized vortex beams in a 4Pi configuration. A spherical dark-hollow beam and hollow beam array can be obtained by vortex beams with topological charge of . A dark channel can be generated using vortex beams with topological charge of . The length of the well-defined hollow beam array and the dark channel is about . These interesting beams are useful in optical trapping and manipulation.
© 2012 Optical Society of America
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