Structure and properties of proton exchange waveguides on Z cut of lithium niobate crystal fabricated in molten benzoic acid with the addition of lithium benzoate

Methods of chemical etching, non-contact profilometry, X-ray analysis and mode spectroscopy enabled to find out that proton exchange channel waveguides formed on Z cut of lithium niobate crystal in the molten benzoic acid with the addition of 3 mol.% of lithium benzoate at the temperature of 225°C were composed of κ
₂
-phase and a thin layer of α-phase. Proton exchange on +Z and -Z faces of the lithium niobate crystal in benzoic acid (with or without the addition of lithium benzoate) occurs at the same rate.