Parameters
wo : waist radius of the incident gaussian beam
z : distance from the lens to the waist of the incident beam
lam : wavelength
fi : back focal length of the lens
wf : mode radius of the fiber optic
T : transmission coefficient at the entrance of the fiber optic
dx : lateral shift of the fiber optic along X axis
dy : lateral shift of the fiber optic along Y axis
dz : defocus of fiber optic
tiltx : tilt of the fiber optic around the X axis
tilty : tilt of the fiber optic around the Y axis
zi : distance from the lens to the waist of the refracted beam
C : coupling ratio