Vijayakumar A, Bhattacharya Shanti
Department of Electrical Engineering, Indian Institute of Technology Madras, Chennai 600036, India.
Appl Opt. 2012 Sep 1;51(25):6038-44. doi: 10.1364/AO.51.006038.
A compact optics configuration for the generation of donut beams for trapping atoms at the micrometer scale using a multilevel spiral-phase Fresnel zone plate (FZP) and a semiconductor laser is proposed. A FZP is designed and a multilevel spiral phase is integrated into it. A spiral-phase FZP with a radius of 1 mm and with more than 1300 half-period zones is designed with multiple angular levels for integer and fractional topological charges, and the device is fabricated using electron-beam lithography direct writing. The performance of the device is evaluated, and the generation of symmetric and asymmetric donut beams is successfully demonstrated.
