Making waveguide frequency converters in lithium niobate robust for handling high-light powers by tailoring the electrical conductivity: theoretical considerations

Making the plus and minus c faces of a periodically-poled waveguide of lithium niobate conductive by suitable doping or by covering with films of sufficient conductivity may short-circuit light-induced space charge fields originating from the bulk photovoltaic effect. We estimate that this should be possible without sacrificing low propagation losses. Hence unwanted light-induced refractive index changes can be prevented, helping to increase the light powers up to which the devices can handle light and frequency conversion happens.