Parameters
wx : half width of the waist in the XZ plane
wy : half width of the waist in the YZ plane
M2x : M square factor (M2) of the elliptical beam in the XZ plane
M2y : M square factor (M2) of the elliptical beam in the YZ plane
lam : wavelength
Dfo : core diameter of the multimode fiber optic
NA : numerical aperture of the multimode fiber optic
T : transmission coefficient at the entrance of the fiber optic
C : coupling ratio