2-PHOTON ABSORPTION-SPECTRUM OF ORIENTED TRANSPOLYACETYLENE

The two-photon absorption spectrum of oriented trans-polyacetylene was measured from 0.55 to 0.96 eV using nonlinear photothermal deflection spectroscopy. The major two-photon absorption resonance is at 0.55 eV; at the peak, Im(chi parallel to)((3)) (-omega; omega, -omega, omega) = 1.6 X 10(-7) esu where Im(chi parallel to)((3)) is the imaginary part of the third order nonlinear optical susceptibility for pump fields along the chain axis. There is an additional two-photon absorption resonance (narrower and weaker) at 0.8 eV. Although Im(chi parallel to)((3)) limits the use of polyacetylene in serial optical computer architectures, a parallel architecture with short optical pathlengths can be used with considerable advantage.