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. (optical waveguides and fibres)