ENHANCEMENT OF 3RD-ORDER OPTICAL NONLINEARITIES OF SOLUBLE VANADYL PHTHALOCYANINES IN DOPED POLYMER-FILMS

The third-order optical susceptibilities chi-1111(3)(-3-omega; omega, omega, omega)s of a soluble vanadyl phthalocyanine derivative ((t-Bu)1.1 VOPc) are studied for thin films and doped polymethylmethacrylate films by optical third-harmonic generation measurements at wavelengths of 1543 nm and 1907 nm. The chi-(3) values are enhanced by a factor of 2-7 at resonant and nonresonant wavelengths, concurrent with an absorption change induced by exposure to solvent vapor. The red-shifted phase (phase II), obtained by the treatment, has larger chi-(3) values than the as-prepared phase (phase I). The enhancement of third-order optical nonlinear susceptibilities in phthalocyanine thin films is discussed in terms of electronic transition and molecular packing.