It is known that in proton-exchanged wave-guides in lithium niobate,1 the crystal structure is modified. We demonstrate that proton-exchanged regions on the c+-face can be etched away selectively using a mixture of HF and HNO3. In this way it is possible to form, for example, a groove with a smooth bottom surface. The unexchanged c+-face of lithium niobate is only very slowly etched by this acid.
© 1991 Optical Society of AmericaPDF Article