Optical second harmonic generation and its photoinduced dynamics in ferroelectric semiconductor Sn$_{2}$P$_{2}$S$_{6}$

By means of optical pump–probe technique, the ultrafast dynamics of nonlinear optical response of the ferroelectric semiconductor Sn$_{2}$P$_{2}$S$_{6}$ crystal excited with a femtosecond laser pulse has been investigated. It has been shown that, under the action of femtosecond pulses, change in optical second harmonic generation occurs in the sample, which can be due to screening of existing electric polarization.