Nonlinear optical properties of fullerene-porphyrin complexes

The nonlinear optical properties, optical limitation, and second-and third-order nonlinearity in a new class of noncovalently bonded fullerene-porphyrin complexes are investigated. Quantum-chemical calculations of the optimal geometry, binding energy, electronic structure, and nonlinear optical properties of donor-acceptor fullerene-prophyrin complexes are performed. As a result of the formation of a complex, the second-order molecular polarizability is higher than in porphyrins by two to three orders of magnitude, depending on the orientation of the molecule, and the third-order molecular susceptibility two orders of magnitude higher. The nonlinear absorption in thin films and solutions of the complexes is measured. In picosecond regimes, absorption saturation at 560 nm wavelength is observed for pulse energy density above 0.01 J/cm(2). A model is proposed for the increase of the optical nonlinearity in complexes as compared with the molecular components. (C) 2010 Optical Society of America.