We demonstrate an experimental scheme that allows the elucidation of the orbital angular momentum discrete spectrum of an arbitrary light signal. The orbital angular momentum spectrum is represented in a Laguerre–Gaussian mode base, and the spectral components are resolved in the frequency domain by exploiting the Doppler frequency shift that is imparted to rotating light beams.
© 2003 Optical Society of America
(070.6020) Fourier optics and signal processing : Continuous optical signal processing
(100.2650) Image processing : Fringe analysis
(120.3180) Instrumentation, measurement, and metrology : Interferometry
M. V. Vasnetsov, J. P. Torres, D. V. Petrov, and Lluis Torner, "Observation of the orbital angular momentum spectrum of a light beam," Opt. Lett. 28, 2285-2287 (2003)