Monday, April 13, 2015

Generation of controllable rotating petal-like modes using composited Dammann vortex gratings

Junjie Yu, Changhe Zhou, Wei Jia, Jun Wu, Linwei Zhu, Yancong Lu, Changcheng Xiang, and Shubin Li

A new type of diffractive optical element, called a composited Dammann vortex grating (CDVG), is proposed for generation of multiple equal-energy controllable rotating petal-like modes extra cavity. As an example, it is shown that a petal-like mode is well generated for each nonzero diffraction order by a binary pure-phase 1×7 CDVG. Mode decomposition is digitally implemented by a programmable spatial light modulator (SLM), and the experimental results show that those generated petal-like patterns are in high mode purity (∼90%) for all six different nonzero orders. Also, controllable rotating petal-like modes are demonstrated when the CDVG is digitally implemented by the programmable SLM, which provides the possibility to quantitatively control the rotation rate of this type of optical tweezers. Furthermore, tunable petal-like modes are also demonstrated experimentally by introducing a vortex incident field with different topological charges.

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