Optimisation of the proton-exchange technology for fabricating channel waveguides in lithium niobate crystals

We have studied the effect of process parameters on the mode profile in lithium niobate channel waveguides produced by low-temperature proton exchange. A model has been proposed for the processes underlying waveguide formation, and has been used to numerically calculate the mode profile for various fabrication parameters. We have identified low-temperature proton exchange conditions which ensure high electro-optical performance of the waveguides and stability towards fabrication errors. The obtained results may be helpful in optimising integrated optical devices and matching them to various types of optical fibres.