# Bent Single Mode Fiber¶

In this tutorial project we compute the fundamental propagation mode of a bent single mode fiber.

The fiber cross section has the same geometry as in the example without bent. E.g, the core has a relative permittivity and a diameter and the cladding has a relative permittivity and a diameter .

Due to the bent of the fiber, the assumption of vanishing tangential components of the magnetic field on the outer boundary no longer holds. This requires a slight change to the boundary definition of the fiber in the layout.jcm:

Boundary {
Class=Transparent
}


The bent is specified by setting AxisPositionX = -0.005 in the project.jcmp (cf. AxisPositionX for the definition and details).

The computation is restricted to the modes of interest by a SelectionCriterion in the project.jcmp file

 1 2 3 4 5 6  SelectionCriterion { NearGuess { Guess = 1.4513 NumberEigenvalues = 1 } } 

The figure below shows the intensity distribution of the computed eigenmodes. On the left the intensity is shown on a linear scale, on the right on a logarithmic scale. The computed mode is mostly y polarized. . The corresponding eigenvalues are stored in the file eigenvalues.jcm.