Toward the generation of broadband optical vortices: extending the spectral range of a q-plate by polarization-selective filtering

Abstract

Optical vortex beams in the visible and near-infrared spectrum over a wide spectral region are generated by a single S-waveplate polarization converter using polarization-selective filtering. A spectral coverage of 600 nm is demonstrated, with maximum efficiency at a wavelength of 530 nm. The broadband coverage is obtained using polarization filtering, which is applicable for any component based on geometric phase retardation. The efficiency of the filtering varies from 50% to 95% depending on the wavelength. This technique has potential application in stimulated emission microscopy and lithography.