Crystalline and optical quality of proton exchanged waveguides

In this paper we demonstrate the possibility of obtaining high-quality proton-exchanged (PE) lithium niobate guides by performing the exchange at high temperatures (300°C) in benzoic acid diluted with lithium benzoate. Rutherford backscattering studies suggest that the higher exchange temperatures avoid the production of niobium dislocations, and, IR absorption measurements suggest that the use of lithium benzoate diluted melts prevents the creation of interstitial hydrogen.