The nonlinear optical characterization of meso-substituted porphyrin dyes

Nine structurally related porphyrins are studied and it is shown how the material parameters that control the optical limiting depend on the molecular structure. Optical limiting measurements at 532 nm on the metal-free, zinc and lead analogues of tetraphenyl porphyrin (TPP), tetra(trimethylsilyethynyl) porphyrin (TTMSAP) and tetra(4-n-butylphenylethynyl) porphyrin (TNBBAP) reveal a strong dependence on the metal atom and peripheral substitution. A double pump/cw probe technique is used to measure the material parameters that control the optical limiting and the results give a strong insight into how the molecular structure influences the individual parameters. These measurements revealed that one of the materials TTMSAP(Pb) has sigma (ex)/sigma (gr) ratio of similar to 45 at 532 nm, which is one of the largest values ever reported. Finally, broadband measurements with a picosecond white-light source show that the position and strength of the excited state absorption features also depend strongly on the porphyrin design.