Optical limiting performances of asymmetric pentaazadentate porphyrin-likecadmium complexes

The optical limiting performances of seven asymmetric pentaazadentate porph yrin-like cadmium complexes have been measured at 532 nm with nanosecond pu lses. In a f/38 geometry, with sample transmission of 0.51-0.80 in a 2 mm c ell, the limiting thresholds for these complexes were 1.4-3.0 mJ/cm(2). The throughputs of these complexes were limited to 0.31-1.13 J/cm(2) for incid ent fluences as high as 3.5 J/cm(2). The limiting throughput was strongly i nfluenced by the nature of the ligand. Lower bounds for the ratio of triple r excited-state to ground-state absorption cross sections have been estimat ed at 3.4-5.7. The lower limiting thresholds, lower limiting throughputs, a s well as the ease of modification of the ligands, make these complexes pro mising candidates for optical power limiters. (C) 1998 American Institute o f Physics.