Impulsive Stimulated Brillouin Scattering Study on the Relaxation of the Polarization Fluctuation in Ferroelectric TGS

The quasi c 33 acoustic mode of ferroelectric TGS is observed by impulsive stimulated Brillouin scattering. The mode is excited by picosecond laser pulses at 500 MHz and 2.0 GHz and its vibrational behavior is probed in real time. The temperature dependence of the velocity of the mode shows an anomaly through a piezoelectric coupling with the fluctuating polarization below the transition temperature T c . The relaxation time τ 0 of the order of 10 -10 s· deg is obtained which is longer than these reported in the previous Brillouin scattering and the ultrasonic studies.