We studied nonlinear absorption of three kinds of porphyrin covalently functionalized SWNTs using Z-scan technique
with nanosecond pulses at 440 nm, 460nm, 480nm, 500nm, and 532nm. The large enhancement of nonlinear absorption
in porphyrin covalently functionalized SWNTs were found at 532 nm. This nonlinear behavior of SWNTs has been
shown to arise from strong nonlinear scattering, and porphyrin exhibits strong reverse saturable absorption at 532 nm.
The porphyrins covalently functionalized SWNTs offer superior performance to the individual SWNTs and porphyrins
by combination of nonlinear mechanism and the photoinduced electron or energy transfer between porphyrin moiety and