Dispersion studies of optical nonlinearity and excited state dynamics in cyclo[4]naphthobipyrroles

Herein we present results from the dispersion studies of nonlinear optical (NLO) properties of three novel cyclo[4]naphthobipyrroles at wavelengths of 600 nm, 640 nm, 680 nm, and 800 nm using picosecond (ps) pulses. NLO coefficients were extracted from Z-scan measurements using ∼1.5 ps pulses. Large two-photon absorption cross sections in the range of 0.2–5.2 × 104 GM and n2 values of ∼10−16 cm2/W were recorded for these moieties. The excited state decay dynamics were investigated using degenerate pump-probe experiments with ∼70 femtosecond pulses near 600 nm. Double exponential fits of the pump-probe data suggested two decay times for all the molecules investigated.