The nonlinear optical properties of fluorescein-doped boric acid glass films have been investigated with sub-nanosecond laser pulses. With the use of degenerate four-wave mixing, large third-order susceptibilities of <i>X</i><sup>(3)</sup> ˜ 10<sup>−7</sup> esu have been measured, connected to the relatively fast decay of the singlet state <i>S</i><sub>1</sub> (Τ = 2.4 ± 0.6 ns). This particular system has a long-lived lowest-lying triplet state (0.1–1 s), and the transient nonlinear-optical and fluorescence properties show a marked dependence on the laser-pulse repetition rate in this time regime.
© 1992 Optical Society of America
Colette Maloney and Werner Blau, "Transient nonlinear optical behavior of fluorescein-doped boric acid glass," J. Opt. Soc. Am. B 9, 2225-2229 (1992)