Have you watched any of Russ Sadler videos on the basics of a fiber laser?
This will get you started if you haven’t…
This is also pretty good basics if you prefer to read…
This is a ‘guide’ to it use with various materials… It’s also based a MOPA laser.
I picked a MOPA type as it’s more flexible from what I have learned… haven’t been able to afford one yet… 
Many people here have these… maybe a better answer will come along.
