Two-photon pumped cavity lasing in novel dye doped bulk matrix rods

Trans-4-[p-(N-ethyl-N-hydroxyethylamino)styryl]-N-methylpyridinium tetraphenylborate (abbre- viated as ASPT) is a newly synthesized lasing dye that possesses a much greater two-photon absorption cross section and much stronger upconversion fluorescence emission than common organic dyes (such as rhodamine), when excited with near infrared laser radiation. Utilizing ASPT doped bulk polymer rods, two-photon pumped frequency upconverted cavity lasing has been accomplished using a Q-switched Nd:YAG laser as the pump source. The wavelength and pulse duration were ∼600 nm and 3-6 ns, respectively, for the cavity lasing; whereas the corresponding values for pump pulses were 1.06 μm and ∼10 ns, respectively. For a 7 mm long sample rod with a dopant concentration d₀=8×10^-3 M/L, the conversion efficiency from the absorbed pump energy to the cavity lasing output was ∼3.5% at a pump energy level of 1.3 mJ. The lasing lifetime, in terms of pulse numbers, was more than 4×10⁴ pulses at 2 Hz repetition rate and room temperature.