Abstract
We present two liquid crystal devices specifically designed to dynamically
generate optical vortices. Two different electrode geometrical shapes have
been lithographically patterned into vertical-aligned liquid crystal cells.
First, we demonstrate a pie-shape structure with 12 slices, which can be adjusted
to produce spiral phase plates (SPP) that generate optical vortices. Moreover,
the same device can be used to generate a pseudo-radially polarized beam,
by simply adding two quarter-wave plates on each side. A second device has
been fabricated with spiral shaped electrodes, which result from the combination
of a SPP with the phase of a diffractive lens. This device acts as a spiral
diffractive lens (SDL), thus avoiding the requirement of any additional physical
external lens to provide focusing of the generated optical vortices. In both
devices, the phase modulation can be adjusted by means of the voltage applied
to the patterned electrodes, in order to change the properties of the generated
optical vortex beams. Experimental demonstrations are provided for different
wavelengths.
© 2012 Crown
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