No abstract

No abstract

No abstract

No abstract

Two-photon induced excited-state absorption and optical limiting properties in a chiral polymer Appl. Phys. Lett. 102, 043308 (2013); 10.1063/1.4790391Spectral dependence of third order nonlinear optical susceptibility of zinc phthalocyanine This work employs the Z-scan technique with 120 fs pulses to investigate the singlet excited state absorption spectra of tetrapyridyl and tetrasulfonatophenyl porphyrins. We have used a three-energy-level model to adjust Z-scan curves in order to obtain the singlet excited absorption cross section from 460 to 800 nm. Starting from these values, we determine the spectra of the ratio between excited and ground singlet state absorption cross sections, whose values are as good as the best found in the literature for reverse saturable absorbers. The results obtained point these porphyrins as good candidates for applications in optical limiting of ultrashort pulses.