According to Wikipedia most carbon fibers consist mostly of carbon (>99%) with some impurities. If we assume the impurities are from the precursor polymer then it matters what the precursor is. It seems that halogenated products are not used as precursors, so it should be safe.
The ease in cutting a material using a laser depends on the ability of the material to absorb the frequency of the radiation and on the material’s heat conductivity. Doing an internet search shows that carbon fiber requires way more than 45W from a CO2 laser in order to cut. So the GF laser cannot cope with cutting carbon fibers you can buy today. As Dan pointed out, for the GF to cut carbon fiber, it’s going to take a specially formulated carbon fiber. And of course in that case it will be laser safe.