Hi all thanks for the add,
I have a BigtreeTech SKR 1.3 running smoothieware-edge with the GLCD 12864 display that I have connected to my diode laser.
Anything under 20% wattage, the laser does not fire and I cannot find how to increase the input and effectively make it turn on at , or under 20%.
Note : In case you aren’t aware, you might want to read http://smoothieware.org/troubleshooting#what-is-wrong-with-mks
About your problem : Not having a linear output is common in lasers, if you look at the laser module documentation you will see there is a config option to set a minimum value, that should solve your issue.