Nature of delayed luminescence and optical nonlinearity in rhodamine 6G doped boric acid glass

The triplet state relaxation dynamics in R6G doped in boric acid glass have been probed using luminescence and transient grating studies. The measured transient grating and luminescence decay signal profiles are explained by excited state relaxation mainly through triplet-triplet annihilation. The observed delayed emission is identified as P-type delayed fluorescence. Our findings support saturable absorption as the mechanism for optical nonlinearity.