@mordiev I did some reasurch a few months ago on them when I found a fiber source for cheap. The big issue I have with them is the wavelength. The wavelength most fiber lasers use is only good for cutting inorganic material, if you try to cut wood it just starts fires. That limitation is posed not by the diodes used but rather the fiber optic cable.
As a side note they usually aren’t just coupled diodes but rather amplified by the use of “pumping diodes”. They keep adding light to coils of fiber with each loop of the fiber gains optical density. It is very cool technology.