OPTICAL LIMITING EFFECT IN A 2-PHOTON ABSORPTION DYE-DOPED SOLID-MATRIX

We recently reported a new lasing dye, trans-4-[p-(N-ethyl-N-hydroxylethylamino)styryl]-N-methylpyridinium tetraphenylborate (ASPT), which has also been shown to possess a strong two-photon absorption (TPA) and subsequent frequency upconversion fluorescence behavior when excited with near infrared laser radiation. Based on the TPA mechanism, a highly efficient optical limiting performance has been demonstrated in a 2 cm long ASPT-doped epoxy rod pumped with 1.06 mu m Q-switched laser pulses at 50-250 MW/cm(2) intensity levels. The measured nonlinear absorption coefficient reached 6 cm/GW for the tested sample of dopant concentration d(0)=4 x 10(-3) M/L. The molecular TPA cross section of ASPT in the epoxy matrix is estimated as sigma(2) = 2.5 x 10(-18) cm(4)/GW or sigma'(2) = 4.7 x 10(-46) cm(4)/photon/s, respectively. Two-photon pumped cavity lasing is also observed in an ASPT-doped polymer rod. (C) American Institute of Physics.