I didn't have any maple, but ran some tests with cherry and white oak.

The white oak has the grain changes so softer areas burned deeper than the harder areas, leaving a striped appearance.

Test is freeform shape (butterfly) and letter outline, single laser beam width lines.
Two letter examples with the center filled.


There is about 1/64" depth here, blew out the soot with compressed air.


Cherry with the tighter grain did much better



These were both bare wood, sanded to 220.

An option is to use masking tape to cover the wood before burning, then fill the cuts with paint.


I've fill this with white, it'll be dry before too long and I'll post what came out.