As an aside, the Maser wikipedia article is a bit incorrect. > The laser works by the same principle as the maser, but produces higher frequency coherent radia

As an aside, the Maser wikipedia article is a bit incorrect. > The laser works by the same principle as the maser, but produces higher frequency coherent radiation at visible wavelengths. There are plenty of lasers in the non-visible spectrum, I use IR lasers all the time.