Models for Saturable and Reverse Saturable Absorption in Materials for Optical Limiting

摘要

The systems used to protect eyes and sensors from frequency-agile laser weapons must be capable, over a relatively broad range of frequencies, of absorbing, refracting, deflecting, or scattering laser radiation of high intensity, even while affording high transmission to light of low to moderate intensity. The design of such devices begins with an accurate characterization of the nonlinear optical response of the candidate active materials. In this work, the relevant material parameters can be extracted from experimentally obtained data only by indirect means: that is, the actual experimental results are compared to the results obtained from a theoretical model employing hypothetical values of the desired parameters, and the parameters of the model are varied until the model results match the experimental data. If this procedure is to work, the model must capture all the essential features of the interaction of the material to be characterized with the laser beam propagating through it. We review the assumptions and approximations underlying the commonly used models for nonlinear absorption, paying particular to the limits of applicability that these impose.