The features of the proton exchange process during the formation of planar waveguides on lithium niobate crystals in the presence of thermogravitational convection

The experimental work has studied the effect of thermogravitational convection on the depth and phase composition of planar waveguides formed on crystals of lithium niobate during proton exchange. The properties of the waveguides were determined using structural and optical methods. The impact of hydrodynamic flows was assessed by counting the number of protons penetrating into the crystal. It has been experimentally demonstrated that the presence of convective flows positively affects the rate of proton exchange. The reduction in the thickness of the layer with an increased concentration of lithium ions, which forms in the acid melt at the surface of the crystal, may be one of the proposed reasons for the observed effect.