The concept of the laser may be attributed to a number of scientists beginning with Tolman and ending with Townes, Basov and Prokorov. Who, actually, could be credited with having a clear enough conception of the physics involved to allow the implementation of the principle could be argued ad infinitum. There is no argument about the first demonstration of the laser by Maiman in 1959. The subsequent explosion in this technology and its associated physics is a matter of record.
William C. Eppers,
"The Role Of The Military In Laser Research And Development", Proc. SPIE 0041, Developments in Laser Technology II, (1 March 1974); doi: 10.1117/12.953832; https://doi.org/10.1117/12.953832