We propose a new solution for modal decomposition in multimode fibers, based on a spectral and spatial imaging technique. The appearance of spurious modes in the spectral and spatial processing of the images at the output of the fiber under test when it has more than two modes is demonstrated theoretically. The new method, which allows us to identify spurious modes, is more accurate, simpler, and faster than previously reported methods. For demonstration, measurements in a standard step-index multimode fiber and a small-core microstructured fiber are carried out successfully.
© 2012 Optical Society of America
Fiber Optics and Optical Communications
Original Manuscript: July 19, 2011
Revised Manuscript: November 21, 2011
Manuscript Accepted: November 23, 2011
Published: January 26, 2012
Duc Minh Nguyen, Stéphane Blin, Thanh Nam Nguyen, Sy Dat Le, Laurent Provino, Monique Thual, and Thierry Chartier, "Modal decomposition technique for multimode fibers," Appl. Opt. 51, 450-456 (2012)