Enhanced Nonlinear Absorption and Optical Limiting Properties of Organic Material ZnTBP-CA-PhR in a DA-ET System

Nonlinear absorption of the organic material Zn-tetrabenzoporphin-crotonicacid-phenoxy resin (ZnTBP-CA-PhR) in the donor-acceptor energy-transfer (DA-ET) system is investigated by the irradiation of Ar⁺ laser on its solid film. A reverse saturable absorption and an enhanced second reverse saturable absorption called the re-reverse saturable absorption are observed in a visible wavelength range. The high performance of optical limiting of the sample possessing low input threshold and an over 95% linear transmission ratio are observed. The physical mechanism of re-reverse saturable absorption is analysed by a five-level rate-equation simulating. According to the Huygens wave diffraction principle and the combination of Kerr effect, thermo-optic effect and optical absorption variation, a mathematical model for the optical limiting of ZnTBP-CA-PhR film limiter is established and the theoretical simulating gives a good agreement with the experimental results.