Prepulse technique for preserving the pulse shape of the stimulated Brillouin scattering

Abstract

We have found that it is possible to preserve the temporal waveform of the reflected wave generated from stimulated Brillouin scattering (SBS) by using a prepulse technique. In this work, the fundamental research has been carried out to preserve the deformed pulse shape reflected from SBS medium. It is well known that the reflected SBS wave has a steep rising edge. If one employs SBS cells in series, the rising edge of the pulse shape becomes steeper every time it reflects at every SBS cell. This deformation of the SBS wave can cause the undesirable effects when we employ several SBS cells in series, such as an optical breakdown in the optical components and the lower reflectivity and lower fidelity of the phase conjugated wave in the SBS medium. A prepulse energy of 5 mJ and a time delay of 5 ns have been measured to be the optimum values under this experimental condition. This prepulse method is useful in developing a multistage system employing several SBS cells in series for high-power laser applications.