Femtosecond time resolved impulsive stimulated Raman scattering in KDP-type Ferroelectrics

Abstract

Femtosecond time resolved impulsive stimulated Raman scattering has been applied to the low lying B2 mode of KH2P04 and KD2P04. The time dependent signals of both crystals show an exponential decay, meaning that both modes are relaxational in nature. The crossing angle of the exciting beams was varied to study the wavenumber dependence of the excited mode. The relaxation time of the individual dipoles of the relaxational mode was calculated to be T = 0.131 ps for KH2P04 and 1 . 0 6~s for KD2P04. Here T~ is the relaxation time of individual dipoles which is given in the equation of the relaxation time T = T~T o / ( T -TO).