PHONON-RETENTION EFFECTS ON STIMULATED BRILLOUIN-SCATTERING FROM MICROMETER-SIZED DROPLETS ILLUMINATED WITH MULTIPLE SHORT LASER-PULSES

When micrometer-sized CS2 and CCl4 droplets are illuminated with multiple 100-ps-duration green laser pulses, which are separated by 13.2 or 171.6 ns, the first few scattered green pulses are weaker than the subsequent pulses. Our data indicate that the Brillouin amplification during a given input-laser pulse is affected by the retention of acoustic phonon amplitude that is generated by the preceding input-laser pulses. Our results suggest the retention of long-lived acoustic phonons generated by the near-forward stimulated Brillouin scattering in droplets.