Reverse saturable absorption and optical limiting in C-60 solution in the near-infrared

We report observation of reverse saturable absorption in C-60 toluene solution for 10 ns duration laser pulses in the wavelength region 710-740 nm, for which the photon energy is less than the energy of the lowest excited singlet state. The observed nonlinear absorption appears to be due to excitation of molecules to the more absorbing lowest triplet state by direct absorption from the ground state. Our results imply that a C-60 based optical limiter can operate over a broad spectral range extending into the near-infrared. (C) 1997 American Institute of Physics.