Although the verse in Exodus (20:22) doesn't specify the type of metal used to cut the mizbeach, the verse in Deuteronomy (27:5) writes specifically that iron is prohibited. This is similarly implied by the verse in I Kings (6:7) "When the Temple was being built it was built of complete quarried stone; hammers, chisels, or any iron utensils were not heard in the temple when it was being built." The Mishna in Middos (3:4) and Rambam (SHM neg. 79, Hil. Beis Hab'chira 1:15) too only write that the prohibition includes iron implements. This implies that lasers would be permitted.
The Mishna (there) states that the reason for the prohibition is that it is inappropriate for iron which was created to shorten man's life to be used on the mizbeeach which was created to extend man's life. Although similar reasoning might debatably be used regarding laser tools, especially laser weapons, they don't seem to have have been included in the prohibition.