Interesting development. I saw a brute force version of this back in the 1970s. My university had a laboratory with a high-energy electric discharge carbon dioxide laser that operated in pulsed mode. For a demonstration example, the laser was focused into the open air of the lab and was discharged. It produced a plasma lightning bolt in mid-air, about a foot long and an inch in diameter (and a tremendous "boom"). It was not the photoelectric effect, because infrared photons do not have a short enough wavelength to ionize a molecule of air. But what was happening was that the focus was small enough and the electric field gradient of the coherent laser wave was high enough to exceed the ionization potential of the molecules. Thus, the plasma.

This same effect is going on, here. Shorter pulses allow the creation of the required high field gradient with shorter times and thus smaller integrated pulse energies (safer). I think you will find that you are going to create white light in every case.