Two-photon absorption spectrum of 3-butoxycarbonylmethylurethane polydiacetylene thin films

Abstract

We report the two-photon absorption (TPA) spectrum of a film of poly[4,6-dacadiyne-1,10-diolbis(3-butoxycarbonyl-methyl-urethane)]—commonly known as poly(3-BCMU)—in the wavelength range λ=1.6–0.7 μm. We find that the TPA coefficient of the film, which was prepared by spin coating, increases from ≈2 cm/GW at 1.45 μm to 170 cm/GW at 0.8 μm. The main features of the spectrum can be accounted for by a three-level model with a two-photon state positioned at 2.8 eV.