Nonlinear absorption behaviors of filled and unfilled d shell metal complexes of 5, 10, 15, 20-tetrakis(4-hydroxyphenyl)porphyrin

► Nonlinear absorption of THPP with Zn2+, Ni2+, Co2+, and Fe3+ were studied. ► The nonlinear absorption behaviors depend on the metal ion and pulse duration. ► The observed nonlinearities were explained using excited-state lifetimes.