Formation of the second-order hot image in broadband laser systems

Abstract

The phenomenon of hot image in high power lasers is closely related to the spatial uniformity of laser beams and the running safety of laser systems. Here we study the formation of the second-order hot image of phase defect in the high-power broadband laser system, special attention is payed to the role of bandwidth of incident beam in the formation of the second-order hot image. It is shown that, as the laser bandwidth increases by either increasing the positive temporal chirp or reducing the pulse duration the intensity of the second-order hot image decreases. However, as the amount of negative chirp increases, the intensity of the second-order hot image increases first but decreases after reaching a maximum value. The distance between the second-order hot image and the nonlinear medium is found to be about half that between the phase defect and the nonlinear medium. The influence of phase shift caused by the phase defect and nonlinear effect on the formation of the second-order hot image is also numerically studied.