I don't know about this particular technology but as a parallel all Florescent Lights operate on a similar concept. They absorb radiation at frequency X and em

I don't know about this particular technology but as a parallel all Florescent Lights operate on a similar concept. They absorb radiation at frequency X and emit in frequency Y where Y is visible light. It appears that the researchers have tuned the emission to a frequency that is not reabsorbed by the atmosphere but emitted unimpeded into space. Pretty clever engineering.