Optical dynamics of aminophenoxy substituted phthalocyanines and the covalent attachments to cadmium telluride quantum dots for picosecond pulse trains

Abstract

Optical interaction of aminophenoxy substituted phthalocyanines with picosecond pulse trains were studied in this work. Additionally, the covalent attachments of phthalocyanines to glutathione (GSH) functionalized cadmium telluride quantum dots (CdTe QDs) were also discussed. A five-level model was applied to simplify the materials. The pulse train has 50 subpulses with 100 ps width for each one and 12 ns spacing. We simulated the dynamical interaction by solving two-dimensional paraxial filed equation coupled with the rate equations based on Crank–Nicholson numerical method. The two-step two-photon absorption (TPA) is the fundamental channel of optical absorption for long pulse trains. Our results indicated that the covalent attachments of phthalocyanines to CdTe QDs show better optical limiting effects than phthalocyanines at the same densities. The cross-sections of one-photon absorption and lifetimes of lowest triplet state as well as the intersystem crossing play important roles in optical limiting effects.