Mode coupling in multimode step-index plastic-clad silica fibers with corrugated surfaces

The state of mode coupling in step-index plastic-clad silica fibers with corrugated surfaces is investigated in this article using the power flow equation. The coupling coefficient in this equation was obtained using our previously reported method. This enabled us to obtain the length of the corrugated piece of the fiber at which equilibrium mode distribution is achieved as well as the length at which a steady state distribution is established. It was found that the plastic-clad silica fibers with corrugated surfaces showed much stronger mode coupling than plastic-clad silica fibers without corrugated surfaces. Consequently, the equilibrium as well as steady state mode distributions were achieved at shorter fiber lengths in plastic-clad silica fibers with corrugated surfaces than in the same type of optical fibers without corrugated surfaces.