THRESHOLD REDUCTION OF STIMULATED BRILLOUIN SCATTERING BY ENHANCING INITIAL BRILLOUIN ULTRASOUNDS

We propose reducing the threshold of stimulated Brillouin Scattering by enhancing the initial Brillouin ultrasounds, since the high threshold results from the low intensity of the sounds that exist in thermal noises. Theoretical analysis shows that the threshold can be reduced by at least one order through introducing comparatively weak Brillouin ultrasounds. Schemes for enhancing the initial ultrasounds are also proposed, including stimulation by transducers, by electroacoustic media or by direct radiation of microwaves.