EXCITED-STATE ABSORPTION-ENHANCED THERMAL OPTICAL LIMITING IN C-60

We report on optical limiting of Q-switched Nd:YAG radiation at 532 nm in an f/5 defocusing geometry using liquid solutions of C60 in 1-chlo ronaphthalene. The nonlinear optical-limiting mechanism is C60 excited -state absorption and enhanced thermal lensing in the solvent. A limit ing threshold energy of 65 nJ, corresponding to an incident fluence of approximately 0.3 J/cm2 at the focus in the solution, was observed wi th a device absorption of 25%.