Ah, I don't mean that the laser outputs only two photons, but that it (might) be designed around 2-photon interactions, so if you have two very-high-intensity IR lasers and the beams meet at a point in space, that crossing point could locally ionize the air as though it consisted of a beam of photons with higher energy.
https://en.wikipedia.org/wiki/Two-photon_physics
https://en.wikipedia.org/wiki/Nonlinear_optics