The Collaborative International Dictionary of English v.0.48:

lase \lase\ (l[=a]z) v. i. [imp. & p. p. lased (l[=a]zd); p.
   pr. & vb. n. lasing.] [by back-formation from laser. See
   laser.]
   To give off a beam of coherent light; -- of a laser.
   [PJC]