Self-focusing of ultrashort pulses above the threshold for catastrophic collapse

Summary form only given. Understanding the propagation of high-power femtosecond laser pulses in optically transparent solids is important for a wide range of intense-field interactions including plasma formation, laser damage, and frequency conversion. Self-focusing is perhaps the most fundamental nonlinear optical process that occurs when a high power pulse propagates through a material. The dynamics of self-focusing in the femtosecond regime is substantially more complicated than in the long-pulse regime, due to the effects of dispersion which strongly couple the spatial and temporal degrees of freedom of the pulse. By analyzing the pulse splitting dynamics that occur as the pulse self-focuses, recent experimental and theoretical results indicate that the slowly-varying envelope approximation breaks down even for pulses that are initially much longer than a single optical cycle.