| Lithium niobate crystal has many excellent electrooptical properties, and people usethis property to develop all kinds of electro-optic devices, such as phase modulator,electro-optic switch and electro-optic waveguide grating, etc. Rare-earth dopedlithium niobate crystals could be used in researching and developing varieties ofactive optical waveguide devices, including the devices based on the electro-opticeffect. And co-doping Mg can effectively inhibit the photorefractive effect.This paperuse Mach-Zed interference measurement system to study the changing rule of theelectro-optic coefficient on different components, rare-earth doped and Mg-Erco-doped lithium niobate crystal.And give a reasonable explanation use the crystaldefect model.The main work includes:(1) Build M-Z interference system to measure the electro-optic coefficient of thesamples. And by comparing the experimental value and theoretical value of congruentsamples to verify the measuring system.(2) Measure about the electro-optic coefficient of different components lithiumniobate crystal. And we found that the electro-optic coefficient is reduced in richcrystal, while in the Li-poor crystal is increased.(3) Measure about the electro-optic coefficient of different rare-earth-dopedconcentrations lithium niobate crystal. And we found that rare-earth ions has no effecton electro-optical coefficient,which is different from others’ results.(4) Measure about the electro-optic coefficient of different Er-Mg co-dopingconcentrations lithium niobate crystal. And we found that with the increase of Mgdoping concentration, the chang of electro-optic coefficient is not monotone. Similarwith the changing of lithium vacancy concentration in the Mg-doped lithium niobatecrystal.(5) Studied the intrinsic defects and extrinsic defect structure of lithium niobatecrystal structure theoretically. We draw the conclusion：electro-optic coefficient isclosely related to the concentration of the lithium vacancy in crystal. |
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