A systematic study of the chemical etching process on periodically poled lithium niobate structures

A systematic analysis on the dynamics of the chemical etching of periodically poled lithium niobate (PPLN) structures grown by off-center Czochralski technique was carried out on crystals prepared under different experimental growth conditions. The etched depth reaches values close to 600 nm and it does not further increase even after long etching times. However, the lateral etching cannot be neglected when the etching times are higher than 5 min. The estimation of the domain widths distribution can be affected by artifacts if the etching conditions are not properly chosen. The best structures are obtained for erbium oxide doping level of 0.3 mol% into the starting melt and the period depends on the pulling and rotational rates instead of on the growing rate. This results support the role of the thermoelectric field in the domain formation at the Curie isotherm.