Two-photon induced fluorescence behavior of DEANST organic crystal

Temporal, spectral, and intensity-dependence behaviors of two-phonon induced fluorescence emission in the DEANST [4-(N,N-diethylamino)-β- nitrostyrene] organic crystal have been investigated by using 1.06 μm pump pulses from a Q-switched Nd:YAG laser. Both the response-retardation time and the tail-decay time of the two-photon induced flourescence signal are less than 1.5 ns, the temporal resolution of our measurement system, with respect to a given pump laser pulse. The fluorescence signal exhibits a square-low dependence of the pump intensity. At the highest pump intensity determined by the sample damage, the two-photon pumped fluorescence intensity is much higher than the corresponding one-photon pumped fluorescence intensity. Also at the highest pump intensity level, the two-photon induced fluorescence intensity from a 1.2 mm thick DEANST crystal is 7.7 times stronger than that from a 1 mm thick liquid cell filled with Rhodamine-6G methanol solution of ≈ 2 × 10^-3 M concentration. Thus, a high quality DEANST crystal is quite a promising organic crystal for two-photon pumped laser devices or frequency upconversion detection.