Z-scan studies on porphyrin derivative

The nonlinear optical properties of a porphyrin derivative (T 3,4, BCEMPP) doped in boric acid glass were probed using the Z-scan technique at different argon-ion laser wavelengths. The nonlinear transmission characteristics exhibit saturable absorption at 457.9 nm and 476.5 nm while they are dominated by excited state absorption at 488.0 nm. The experimental observations are explained by using the four-level saturable absorber model. Saturation intensity, excited-state absorption cross-section, light-induced changes in the absorption and the refractive index along with its sign were determined at these argon-ion laser wavelengths. Further, optical limiting characteristics of this sample were studied. The observed limiting action is consistent with the Z-scan studies.