用新型非线性材料硅酸镓镧(LGS)晶体制作了电光调制器,研究了单晶硅酸镓镧晶体的电光效应。利用极值法和倍频法测定了硅酸镓镧晶体的半波电压值,计算出电光系数γ11分别为1.85 pm/V和1.90 pm/V,对比发现倍频法比极值法实用、快速、方便。测定了在0.3～0.6328 μm波长内硅酸镓镧单晶的旋光率为21.1°～2.6°/mm。利用自制的高压调制电源进行了调制实验,实验结果表明:有旋光性非线性材料硅酸镓镧晶体是一种新型电光晶体,可用作电光调制器,调制信号稳定。

A new electro-optic modulator is fabricated using langasite (LGS, La3Ga5SiO14) crystal, and the electro-optic effect of langasite single crystal is studied. The half-wave voltage and the corresponding electro-optic coefficient γ11 are determined by the extreme method as well as the double frequency method. It is shown that it is relatively easy, convenient to measure γ11 by the double frequency method compared with the extreme method. The specific optical activity of 21.1°～2.6°/mm in the range of 0.3～0.6328 μm of langasite is determined by using a new method. The electro-optic modulating experiment of langasite crystal has been completed with home-made high-voltage modulating power. The results show that langasite crystal having optical activity is a kind of new electro-optic crystal and suitable for fabricating electro-optic modulator.