Optical power limiting processes in C60 solutions have been measured in a double-pass geometry designed to produce high beam attenuation. Based on the concentration of C60 and measured attenuation of laser fluence, it was found that, at high intensities, more than 100 visible (532 nm) photons per C60 molecule can be absorbed during a single 7-nanosecond laser pulse. The requisite features of such efficacious attenuation mechanisms are briefly discussed and a model meeting the requirements is described.

Magnified imagery of the focal volume within a nonlinear material, following the arrival of a high power laser pulse, provides insights on the response of the material. Emitted and scattered light images are presented along with time-resolved shadowgraphs (obtained through a pump-probe scheme) showing the response from various limiting materials in both liquid and solid hosts. The different types of images taken together make it possible to determine what occurs and where it occurs within the limiting material. Often unsuspected phenomena are found to be important. Conclusions from the data and the general utility of the technique are discussed.

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