Figure 1. Reference refractive index profile of real fiber sample LOMF Corning OM2+/OM3: (a) full profile; (b) local profile fragment around core center

From

Design of Refractive Index Profile for Multimode Optical Fibers with Low Differential Mode Delay

Anton V. Bourdine

Journal of Optoelectronics Engineering. 2013, 1(1), 5-13 doi:10.12691/joe-1-1-2