Let me know if people find it too impenetrable and/or dumbed-down.
Very good work. You are also right that population inversion "is a necessary step in the workings of a laser", and that the it could be placed under laser science. And perhaps it is actually better to have a long article explaining all you need to know about lasers. But just keep writing - we can alway reorganize it afterwards. --css
Ok, it's now pretty clear most of this should go in laser science. I'll do so after clarifiying a few more points.