There are probably open source packages that can do this. There have been several large open source updates recently but I am not a user of laser/plasma machines.
If the operational needs of laser/plasma are similar have a look at a very inexpensive product suite called "SimplyCam". It includes modules for SimplyLaser and SimplyTurn as well as the standard router module. Modules are called by name from the same software package. You can download it and try full features without a licence to see if it can do what your need before deciding if you want a license (about $50.00).
The only limits of the unregistered version is you can't save a drawing and it will only generate about a 100 lines of G-code but other than that it is fully functional.
You can have a look at the following web site: MR-Soft Nc Software Tools
I am not affiliated with them except for being a very happy customer for many years :-)
Let us know if it is useful. One day I'll get a laser machine...