OPTICAL LIMITING PROPERTIES OF A ZINC PORPHYRIN POLYMER AND ITS DIMERAND MONOMER MODEL COMPOUNDS

We report on the strong decrease in laser light transmission with incr easing excitation intensity observed in thin films of a zinc porphyrin polymer and its dimer and monomer model compounds. Nonlinear transmis sion measurements performed at 532 nm using 500 ps laser pulses show d ecreases of 40%, 60% and 65% at input fluences of 0.01 J/cm(2) for the monomer, dimer and polymer thin films, respectively. Its application as an optical limiting device for the protection of the eyes and optic al sensors from high-fluence laser pulses is assessed. Additional pump -probe measurements performed at 595 nm using 0.8 ps excitation allow us to discuss the strong response in terms of a six-level model of the electronic structure. (C) 1998 Elsevier Science B.V. All rights reser ved.