Increased optical damage resistance in lithium niobate

We have confirmed greatly improved resistance to photorefractive damage in compositions of lithium niobate containing 4.5 at. % MgO or more. Holographic diffraction measurements of photorefraction demonstrated that the improved performance is due to a hundredfold increase in the photoconductivity, rather than a decrease in the Glass current. The diffraction efficiency shows an Arrhenius dependence on temperature, with an activation energy of 0.1 eV for the damage‐resistant compositions, compared with 0.5 eV for undoped or low‐magnesium compositions. The damage‐resistant compositions are distinguished by a 2.83‐μm absorption line instead of the usual 2.87‐μm line due to the OH‐stretch vibration.