Ferroelectric domain imaging by defect-luminescence microscopy

In order to study the role of defects within the domain inversion process in ferroelectric LiNbO3 crystals, we investigated the optical properties of intentionally introduced Er3+ defect complexes across a 180° domain wall produced at room temperature by electric-field poling. Using site-selective excitation-emission spectroscopy for well chosen excitation energies, we found drastic differences in the Er3+ emission, which are due to a rearrangement of the defect complexes. We used these changes in a confocal luminescence microscope to image ferroelectric-domain structures. This powerful imaging method with a 700 nm, 50 ms spatial and temporal resolution can be used to study real-time dynamics of domain walls.