Wet etchingX-cut LiNbO3 using diluted joint proton source

By adding lithium carbonate into a mixture of benzoic and adipic acids as the proton-exchange source, the wet-etched ridge structure in x-cut LiNbO3 is successfully fabricated. Both the etched depths and profiles are demonstrated to be outperformed those of the traditional wet etching method using pure benzoic acid, which is diluted by lithium benzoate. Meanwhile, the etched surfaces are shown to be very smooth. The proposed wet etching method can be further applied to fabricate high-quality components with ridge structure in x-cut LiNbO3.