We show that the intensity distribution of an optical vortex contains information of its order. Specifically, the number of dark rings in the Fourier transform of the intensity is found to be equal to the order of the vortex. Based on this property and the orthogonality of Laguerre polynomials, we demonstrate the feasibility of an experimental technique for determining the order of optical vortices. It shows the beauty of going to complementary spaces, which has been employed earlier also to find the information not available in other domains.
© 2011 Optical Society of America
Diffraction and Gratings
Original Manuscript: August 22, 2011
Revised Manuscript: October 6, 2011
Manuscript Accepted: October 8, 2011
Published: November 15, 2011
Shashi Prabhakar, Ashok Kumar, J. Banerji, and R. P. Singh, "Revealing the order of a vortex through its intensity record," Opt. Lett. 36, 4398-4400 (2011)