MULTIPHOTON EFFECTS IN THE POLYDIACETYLENE POLY BIS(P-TOLUENE SULFONATE) OF 2,4-HEXADIYNE-1,6-DIOL (PTS)

Multiphoton absorption was investigated in single crystals of the polymer poly bis(p-toluene sulfonate) of 2,4-hexadiyne-1,6-diol (PTS). Using modified growth and polymerization techniques, high optical quality crystals were grown and their linear absorption spectrum measured. Very large four-photon absorption was measured using Z-scan with a value of alpha(4) = 0.3 cm(5)/GW(3) obtained at 1600 nm. From the known one and two-photon absorption spcctra, the three- and four-photon spectra are predicted to overlap. This leads to three-photon enhanced, four-photon absorption which is interpreted as the mechanism responsible for such large four-photon absorption.