Third-order nonlinear optical response in polymer thin films incorporating porphyrin derivatives

The third-order nonlinear optical properties of several porphyrin derivatives incorporated in thin films of polymethylmethacrylate have been measured by degenerate four-wave mixing at 598 nm with 1 ps pulses. Both the magnitude and dynamics of the nonlinear response are measured, with each system exhibiting both a subpicosecond response and a more slowly decaying response (10 ps-1 ns) owing to excited-state population. A copolymer of silicon phthalocyanine and methyl methacrylate exhibits a fast recovery time (15 ps) and no observable long-time (∼ns) component of its nonlinear response, as well as an absorption band twice as narrow as that of guest/host samples of the same material.