Nonlinear photochemistry of polymer laser media in high-intensity light fluxes

An investigation was made of photobleaching of organic dyes in polyurethane matrices irradiated with high-intensity monochromatic light fluxes corresponding to the main absorption band. The probability of dissociation of dye molecules k, reduced to a unit dose, depended nonlinearly on the intensity of the exciting light I. In the range I > 100–150 MW/cm² the dependence k (I) reached its maximum, which depended on the structure of the dye and differed by several orders of magnitude for dyes of different classes. The observed dependences were described using a three-level model of electronic–vibrational states. Some practical recommendations were made for increasing the service life of dye-activated polymer laser elements.