Pulse response and microbending losses of an optical glass-fibre waveguide with a bump in its index profile

It is shown that a short light pulse is split into two separate output pulses when transmitted through a graded-index fibre with a refractive-index bump in its centre. For the fibre investigated, the bump acts as a monomode waveguide. This monomode waveguide turned out to be much less sensitive to microbending than the multimode graded-index waveguide, which is in agreement with existing theories.