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We are modeling the propagation of high intensity laser pulses through nonlinear optical materials including interactions of two-photon absorption, excited-state absorption and nonlinear refraction including thermal refraction. We have developed a preliminary code written in C++ applicable to Pentium-based PC's that is currently running and being tested against known results over a large range of input parameters. In particular, this code is being used to model optical limiting devices for sensor protection applications. While agreement is excellent for most nonlinearities at relatively low input energies, at high inputs, where transmittance values can drop to low levels, deviations are observed. It is thought that acoustic effects arising from thermal transients may be responsible. This is currently under investigation. We have recently developed an approximate solution for these photoacoustic nonlinearities that is computationally much faster than our previous code which was so computationally intensive that practical problems were prohibitive. This code is now being tested to verify its range of validity.