A simple optical system for the self-homodyne detection of the orbital angular momentum (OAM) carried by optical
beams is introduced. We propose two different schemes based on the use of optical hybrids, which could detect the
OAM mode number, even when the input beam might be slightly distorted. A balanced receiver is used to perform a
self-homodyne measure of the optical signal from two different locations at the beam wavefront.
Belmonte, A., Juan P. Torres. Self-homodyne detection of the light orbital angular momentum. "Optics letters", 15 Juliol 2012, vol. 37, núm. 14, p. 2940-2942.