Enhancement of /spl chi//sup (3)/ of squarylium dye j-aggregates in infrared region by two-photon resonance

Third-order nonlinear optical coefficient (/spl chi//sup (3)/) of organic J-aggregate film was measured in infrared region using Z-scan technique. Enhancement of /spl chi//sup (3)/ due to two-photon resonance was clearly observed, demonstrating the possibility of operation at telecommunication wavelength.