A simple technique for determining the topological charge of supercontinuum optical vortices is presented. The spatial dispersion inherent to generating broadband vortices with a single forked grating is compensated with a double-pass arrangement from a single spatial light modulator. The vortex charge is determined by inspecting the diffraction pattern through a triangular aperture. It is shown that the topological charge is constant, and can be consistently measured, across a wide range of colors.
© 2012 Optical Society of America
Diffraction and Gratings
Original Manuscript: February 8, 2012
Revised Manuscript: June 13, 2012
Manuscript Accepted: June 16, 2012
Published: July 16, 2012
Matthew E. Anderson, Heath Bigman, Luís E. E. de Araujo, and Jan L. Chaloupka, "Measuring the topological charge of ultrabroadband, optical-vortex beams with a triangular aperture," J. Opt. Soc. Am. B 29, 1968-1976 (2012)