Two-photon induced amplified spontaneous emission from needlelike triphenylamine-containing derivative crystals with low threshold

Two-photon induced amplified spontaneous emission (ASE) characteristics of a needlelike crystal were studied. Under two-photon excitation, the upconverted light emission was confined within the crystal and self-waveguided along the needle axis then radiated from the needle tips. The full width at half maximum of the two-photon excited fluorescence reaches 6.5 nm and ASE threshold is as low as 0.29 mJ pulse(-1) cm(-2) for the N-(4-(4-(4-(diphenylamino)styryl)styryl)phenyl)-N-phenylbenzene amine crystal, comparable with those achieved by single-photon pumping. The needlelike crystal is shown to be a promising candidate for frequency up-converted organic semiconductor microlasers.