OPTICAL LIMITING MECHANISMS IN C-60 SOLUTIONS

We report on optical limiting mechanisms in C-60/toluene solutions over a wide range of laser fluences. Nonlinear absorption in C-60 can be modeled by reverse saturable absorption. However, our optical limiting experiments are sensitive to additional optical loss mechanisms. We observe thermally induced beam distortions, luminescence, and photo-decomposition. At high fluences many materials form plasmas and exhibit very strong optical limiting. However, C-60/toluene does not form a plasma even for incident energies 40 times the plasma threshold in pure toluene. At these high incident energies, 5 mJ, we do see a laser induced reaction of the solution with the Pyrex cuvette, etching of the Pyrex, and numerous organic products.