Measurement of Wavelength Dependence of Electro-Optic Coefficients r22 of Non-doped and 5% MgO-doped Congruent LiNbO3 Crystals and 1.8% MgO-doped Quasi-stoichiometric LiNbO3 Crystal by Multiple Reflection Interference Method

The electro-optic coefficient r ₂₂ in the wavelength range from 409 to 1580 nm was measured for non-doped and 5% MgO-doped congruent LiNbO₃ crystals and 1.8% MgO-doped quasi-stoichiometric LiNbO₃ crystals in a simple optical system using a multiple reflection interference method capable of producing high-precision results without the application of antireflection film to the end faces of the crystal. The influence of the manufacturing errors of the electrooptic crystals was discussed on the measurement of the r ₂₂ coefficient. The experimental errors are less than approximately 0.5% in the wavelength range from 409 to 1064 nm and approximately 1% from 1340 to 1580 nm. It was further shown that polarizing of the laser along X axis resulted in highly accurate measurement of the r ₂₂ of LiNbO₃ crystals.