Transient phase conjugation using stimulated Brillouin scattering (a numerical study)

Summary form only given. Phase conjugation by stimulated Brillouin scattering has motivated many experimental and theoretical investigations of the SBS process. The transient regime of SBS is important because it affects the fidelity and reflectivity of SBS both when the pulse duration is comparable to the phonon lifetime of the SBS material and whenever there are sharp increases in the pump field or stochastic fluctuations in the Stokes field. Although experiments on the transient fidelity of SBS have been reported, there is only an incomplete theoretical and numerical understanding of the phenomena involved, especially in the cases of short coherence length pulses, where a broad band of temporal modes are involved, and of other nonlinear effects such as self focusing, breakdown and thermal lensing. Furthermore, most current models of SBS (to the best of our knowledge) use either one dimensional, steady state, undepleted or non-focusing geometry of SBS. To improve our understanding of these phenomena we have formulated a new efficient and compact numerical approach to develop a transient three-dimensional model of SBS initiated from noise and including focusing geometry. The model has the capability of dealing with any number of spatial modes in the pump and Stokes pulses (restricted by the computing time) and enables us to study the phase conjugation of aberrated beams.