We put forward a type of receiver for coherent detection of the photon orbital angular momentum (OAM). A coherent array receiver, consisting of multiple subapertures, with each subaperture coupled to a single-mode fiber, maps the complex optical field in the image plane. Using digital samplers connected to each array element, the local electrical signals resulting from the detection process can be measured coherently, moving the complexity of the full OAM measurement from the optical domain to the digital domain. By computer processing the coherent electrical patterns obtained, one can retrieve full information (amplitude and phase) of the different OAM components that constitute any incoming beam.
© 2013 Optical Society of America
Lasers and Laser Optics
Original Manuscript: November 15, 2012
Revised Manuscript: December 19, 2012
Manuscript Accepted: December 19, 2012
Published: January 15, 2013
Aniceto Belmonte and Juan P. Torres, "Digital coherent receiver for orbital angular momentum demultiplexing," Opt. Lett. 38, 241-243 (2013)