The relations between the far-field intensity distribution and the corresponding modal power distribution resulting from differential excitation are employed to determine the index profile of a multimode fiber. The modal propagation constant and the modal time delay are determined from the far-field distribution, eliminating the need for ultrafast sources and detectors, required in the direct time-delay measurements. The temporal impulse response is reconstructed numerically from the modal time-delay distribution for specific excitation conditions.
© 1983 Optical Society of America
Haim Kobrinski and Gerald J. Herskowitz, "Characterization of optical fibers by a differential excitation technique," Appl. Opt. 22, 3880-3886 (1983)