Nonlinear effects in aspect ratio based far-field characterization of single-mode trapezoidal index fibers

We investigate the effect of Kerr nonlinearity on the angle of beam divergence of single-mode trapezoidal index fibers from its linear and nonlinear values. From comparison of angle of beam divergence in presence and absence of Kerr nonlinearity, the nonlinear effect for each aspect ratio is observed to be more profound in lower values of normalized frequency. Moreover, the triangular index profile supersedes the other index profiles in respect of relative change of angle of beam divergence. It should give the system users and developers a much better control over far-field related calculations and can be widely used for experiments in presence of optical nonlinearity.