Nonlinear Optics (The Lebedev Physics Institute Series)

In this paper we investigated the dynamics of the processes occurring in a Q-switched laser. This work was stimulated by the lack of data on the spatial and temporal development of generation, despite the obvious importance of such data in the use of giant light pulses in in­ vestigations of the nonlinear interaction of radiation and matter. From a systematic con­ sideration of a relatively simple model of a Q-switched laser we analytically investigated two main phases of development of the giant pulse - the phase of linear development of generation, which begins with amplification of the spontaneous emission in the modes, and the phase of nonlinear transverse development, during which the giant light pulse proper is emitted. In ad­ dition, fo r a thorough inve stigation of the picture of development of the pulse as a whole the equations were numerically integrated. ' Subsequent experiments [26, 27] confirmed the occurrence of transverse development of the giant pulse, while recent experiments on nonlinear amplification [28] have shown the sig­ nificance of this effect in the propagation of the giant pulse in a nonlinear medium. A know­ ledge of the transverse development of the giant pulse would appear to be essential for the exact determination of the true strength of the light field in experiments on multi photon pro­ cesses [29]. The developed theory also leads to recommendations for the design of lasers to generate giant light pulses of minimum length and minimum divergence of emission.