Third order optical nonlinearities of eight-β-octa-octyloxy-phthalocyanines

The third order nonlinear optical properties of the eight-β-octa-octyloxy-phthalocyanines in chloroform were investigated by Z-scan using ps laser at 532 nm. The excited state absorption cross section and the nonlinear refractive cross-section were determined. Eight-β-octa-octyloxy-phthalocyanine free base and eight-β-octa-octyloxy-nikle-phthalocyanine both posses large σes/σ0 ratio and positive σr, and the introduction of nikle ion reduces these values. Optical limiting performance was studied using multi-level model, the result shows that eight-β-octa-octyloxy-phthalocyanine free base has a much lower limiting threshold.