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

Abstract

The quasi c₃₃ acoustic mode of ferroelectric TGS is observed byimpulsive stimulated Brillouin scattering. The mode is excited bypicosecond laser pulses at 500 MHz and 2.0 GHz and its vibrationalbehavior is probed in real time. The temperature dependence of thevelocity of the mode shows an anomaly through a piezoelectric couplingwith the fluctuating polarization below the transition temperatureT_c. The relaxation time τ ₀ of the order of 10^-10 s·deg is obtained which is longer than these reported in the previousBrillouin scattering and the ultrasonic studies.