Pulse compression by SBS. Explain qualitatively why the Stokes radiation excited by SBS in the backward direction can be considerable shorter in duration than the exciting radiation. How must the physical length of the interaction region be related to the duration of the laser pulse in order to observe this effect? Write down the coupled-amplitude equations that are needed to describe this effect and, if you wish, solve these equations numerically by computer. What determines the minimum value of the duration of the output pulse