Efficient multistage SBS amplifier

A two-stage weak-signal SBS amplifier scheme with an independent pumping of both amplification stages is proposed and implemented. This scheme is devoid of the disadvantages inherent in a single-stage amplifier because the competitive influence of pump-correlated noise components is suppressed in it due to their amlification either only in the first stage or only in the second one. It is experimentally shown that this system allows amplifying weak signals by a factor of 10⁶ – 10⁹ for a bandwidth determined by the type of SBS-active material involved and its gain increment (10^-2 – 10^-4 cm^-1). The gain of ~10⁸ is obtained with retention of the spatial characteristics of the signal being amplified.