Study of ferroelectric domain switching by domain wall induced light scattering

The 90°-light scattering on domain walls was probed in various strontium barium niobate (SBN) crystals for studies of the ferroelectric switching under pulsed fields. The validity of this optical method is proved by a good agreement of the switching parameters deduced from optical scattering data with those obtained with electric methods. Scanning of the scattering over the crystal bulk revealed local specialities of the switching, particularly, a marked distribution of the domain wall density D along the polar axis with a maximum close to the negative electrode. In compliance with these in situ observations, the electro-optic coefficient r c reveals a position dependence in all SBN crystals poled in the ferroelectric phase, r c decreasing from the positive to negative electrode. This regularity is interpreted in terms of the domain density distribution D ( z ) and accounted for by an asymmetry of the domain nucleation.