Comparison of Methods for Calculating Coupling Length in Step-Index Optical Fibers

A recently reported function for calculation of the coupling length at which the equilibrium mode distribution is achieved in step-index plastic optical fibers is compared to a long established calculation method and to experimental findings. The recent function, while simpler to apply as it eliminates the need to numerically solve the power flow equation repeatedly for every case, is also more accurate for high numerical aperture (0.45 to 0.5) plastic optical fibers.