I built a couple of laser diode heads for my desktop mini-mill. One uses a 3 watt 445 nm multi-mode blue laser. The other uses a 0.7 watt (driven at 0.5 watts max) 405 nm single-mode near-ultaviolet laser. Single mode lasers can be focused to a smaller spot than multi-mode lasers. My main application is cutting solder paste stencils.
Here is a Tweakie Bike cut from 0.032" bassword (0.063" balsa cuts the same) using the 405 nm laser. Cutting was at 8"/minute. Two passes were used to assure that the bits fell out... otherwise residual fibers can cause them to hang and punching them out can break things (particularly in balsa) due to the tiny features.
I converted Tweakies g-code to DXF and then converted the DXF to Mach3 gcode to control my laser. Laser power is set via the "S" spindle speed word. Spindle power mcodes control the laser power supply and coolant mcodes control the co-axial assist air (via a small 12V diaphragm pump).
The features in the DXF are 1mm wide. After cutting, the features measured 0.98mm... works out to a kerf width of 0.0005" ! The laser lens is 4" from the cutting surface. With a shorter throw, the spot can supposedly be focused to 0.01mm