Way back in 2014 I posted the simple solution I use for controlling my laser output power using the Mach3 generated PWM signal.
https://www.machsupport.com/forum/index.php?topic=12444.msg194200#msg194200That method, although just fine for me, is not suitable for lasers which use an Active High TTL input so an alternative was investigated.
Although it is a little more complicated because a 5 Volt power source is required, using a basic logic IC the Mach3 generated PWM can easily be gated ON / OFF using the M11 / M10 command set thus controlling laser output power.
I have attached schematics for both TTL(High) and TTL(Low) versions of the same concept.
By referring to the truth table you can see that condition C would be used for laser OFF with condition D used for laser ON (at the designated PWM) and condition F would be used with 100% PWM for full power laser output.
Food for thought perhaps ?