How big is a MICRON ?
Basically human hair size is approximately 100 micron but the size of both multimode and singlemode core size is 50 micron or 62.5 micron and 9 micron respectively.
One can conclude that human hair size is thicker than the size of fiber optics core !!!
I have been in the field of fiber optics since early 1990s. I gained fiber optics skills and knowledge via my working experience as end-user, main contractor and sub-contractor and finally as an optical fiber enterpreneur.