REVERSE SATURABLE ABSORPTION AND OPTICAL LIMITING IN C-60 SOLUTION INTHE 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 low est excited singlet state. The observed nonlinear absorption appears t o be due to excitation of molecules to the more absorbing lowest tripl et state by direct absorption from the ground state. Our results imply that a C-60 based optical limiter can operate over a broad spectral r ange extending into the near-infrared. (C) 1997 American Institute of Physics.