This small Matlab library contains functions for finding and plotting all the LP modes of a step-index fibre under the weakly guided approximation. The function find_LP_modes numerically solves the eigenvalue equation:
where is a Bessel function of the first kind of order , is a Bessel function of the second kind of order and
where is the fibre V number and is the parameter to be solved.
The images below are example amplitude and intensity plots of an LP mode.