Optical Field propagation with Birefringence

I am trying to simulate the propagation of a optical field in an optical fiber. I used the fourier split step algorithm described in the Agrawal book Nonlinear Fiber optics.

Currently, I am trying to extend the algorithm to include polarization effects. Birefringence and PMD.

I am using as a reference the paper: "A Time-Domain Optical Transmission System simulation package accounting for nonlinear and polarization-related effects in fiber" IEEE Journal on selected areas in communications vol 15 no 4 may 1997.

Question:

1) Does anyone knows where can I find more references / info / code etc. on how to extend my algorithm.

I am using Matlab but any help will do.

2) If anyone is interested, I was thinking of creating a group, under sourceforge, with aim to create a free-tool for fiber optic transmission simulation. All the tools I know r commercial and therefore forbidden for me!

3) is there a free(!) toolbox in matlab that does this?

thank you in advance.

PS: A source for the (single polarisation) fourier split step algorithm: