For the strongest laser pointer, is usually described as “guided wave optics” theory, the guided wave equation, simulation of coupled mode equations; but in a large core diameter, high numerical aperture of the case, can be described using the “ray optics” theory, then you can use a “ray tracing” model.
The strongest laser pointer has a different spot size and divergence angle, so it has different beam quality. It can effectively guide mode according to the refraction rate of the sequence, usually first guided modes like the Gauss beam, so it has the best beam quality, high order mode beam quality generally is getting worse.
Any strongest laser pointer beam injection, in the mathematical equivalent of decomposition to the guided mode and a series of radiation mode, radiation mode eventually disappear, leaving only the guide mode. So, if the fiber is injected into the single-mode fiber, the output beam quality will be excellent, close to the theory of Gauss beam, but because of the radiation modes disappear. There will be a loss of power.
If strongest laser pointer is injected into the super multimode fiber, even Gauss beam injection, as long as the match is not good, there will be a lot of guided modes excited, causes the output beam quality. The simulation is estimated that you say fiber multimode fiber super, this time between the input and output beam quality should have no clear relationship.