Abstract

A phase conjugate mirror with excellent fidelity and high reflectivity of >50% was obtained from disodium fluorescein doped in boric acid glass by degenerate four wave mixing, by using a cw Ar⁺ laser at 488 nm. The third order nonlinear susceptibility was estimated to be of the order of ~10 esu. The nonlinear mechanism accountable for the grating formation was found to be the resonant enhancement by the excited singlet and triplet states. Nine samples of different dye concentrations in the glass were pre pared. The grating decay times by degenerate four wave mixing and holographic process using a He-Ne laser as a reading beam were found to be concentration independent. The grating decay curves from the above mentioned techniques as well as the phosphorescence decays were found each to have two decay times of the order 0.1 and 0.03 s, 0.3 and 0.07 s, and 0.7 and 0.2 s, respectively. Spectroscopic studies of the sample at room and liquid nitrogen temperatures revealed the reasons for the presence of two decay times for each curve to be phosphorescence and delayed fluorescence. The discrepancies between the decay times for each process above will be discussed.

© 1992 Optical Society of America