Introduction to multimode (MMF) and slightly multimode (FMF) optical fibers
Multimode, few-mode or multicore optical fibers

As we saw earlier, the modal content of an optical fiber, at a given wavelength, is fixed by the normalized frequency, $V,$ which in turn depends on the guide's opto-geometric properties. Unlike a single-mode optical fibre, which, at the wavelength of use, only allows propagation of the ${\mathit{LP}}_{01},$ multimode fibers, on the other hand, typically support from two to ten groups of modes (in the case of FMFs) up to several dozen or even several...