There are thousands of different chromophores and most of them are bi-phasic. This means that they are reactive to more than one color and exist in two distinct states. One state is when they are armed with an electron to give off and one is when they are disarmed or devoid of electrons to give.
We use the original pulse of light in PAWS to get the chromophore to give off its electron to the underlying biology. Then, where typically there is a slow multi step redox reaction to get the chromophore to re-arm itself, we use a second and different wavelength of light to instantaneously re-arm the chromophore with a new electron.
This shortens the refractory period of the chromophore and allows more light initiated information to be driven to the organism.
Because the reactions of the organism are photo-chemical reactions that happen in the order of femtoseconds, it is not necessary to deliver light to plants or animals with on off cycles that mimic the sun. Instead, these signals are given as a function of ratios of near-red, far-red and blue wavelengths hundreds of thousands of times per second. This is what drives day length and seasonality information to the organism.