I believe the point of the 8° inclined cleave is to reduce the amplitude of the backwards travelling optical fibre mode reflected from the end of the fibre. The Beam Propagation Method will not shed any light on this (no pun intended), as the BP method cannot simulate reflections. On the other hand, I don’t think the inclined facet will change the far field pattern significantly, except for the change in the direction of optical axis that could be anticipated from Snell’s law.