Optical limiting properties of optically active phthalocyanine derivatives

The optical limiting properties of four optically active phthalocyanine der ivatives in chloroform solutions and epoxy resin thin plates were measured at 532 nm with 10 ns pulses. The excited state absorption cross-section sig ma (ex) and refractive-index cross-section sigma (r) were determined with t he Z-scan technique. These chromophores possess larger sigma (ex) than the ground state absorption cross-section a(0), indicating that they are the po tential materials for reverse saturable absorption (RSA). The negative sigm a (r) values of these chromophores add to the thermal contribution, produci ng a larger defocusing effect, which may be helpful in further enhancing th eir optical limiting performance. The optical limiting responses of the thi n plate samples are stronger than those of the chloroform solutions. (C) 20 01 Published by Elsevier Science B.V.