Combined excitation emission spectroscopy of defects for site-selective probing of ferroelectric domain inversion in lithium niobate

We review our detailed optical characterization of Er and Cr defects in LiNbO3 and utilize the obtained knowledge for the investigation of ferroelectric domain inversion. We present a novel method for imaging of ferroelectric domain walls that is based on spectroscopic changes of the defects and allows noninvasive study of the domain inversion process and its dependence on defect/domain wall interaction with high spatial and spectral resolution. We find that defect dipoles and their relative orientation are influenced within a region of 20 μm around the domain wall. The location of the Er ion on Li-site is modified from its position in the bulk within a region of 4 μm of the domain wall.