Determination of SBS-induced damage limits in large fused silica optics for intense, time-varying laser pulses

The propagation of intense 3rd harmonic light (0351 μm) through large optical components of the Nova laser results in fracture damage of the center of the component. This damage is caused by an intense acoustical wave brought to focus in the center by reflecting off the circular edge of the optic. The source of this wave is light generated by transverse stimulated Brillouin scattering (SBS). By taking into account the transient gain characteristics of the SBS, we can correctly predict the pulse energy that would cause damage for any time variation in intensity in the pump beam, and predict the relative intensity of the Brillouin light. Our model is based on the transient behavior of a first order linear system.