研究了在X切铌酸锂基底上制作沿Y方向传输光的电光长周期波导光栅的理论模型。利用有效折射率法和射线法进行理论分析获取波导的各项参数。针对所建议的波导光栅结构，将调谐电极置于波导两侧，无需跨过波导就可获得最大的电光调制。该结构的电极间距小(小于10μm)，使得在较小的驱动电压(1.6V)下就可以实现阻带幅度高达28dB的长周期波导光栅。对该光栅模型的研究为开发低驱动电压的高速电光长周期光栅提供了理论依据。

The theoretical model of electrooptic (EO) longperiod waveguide grating (LPWG) fabricated on Xcut Ypropagation LiNbO3 was investigated. The parameters of LiNbO3 waveguides were obtained from theoretical analysis with the methods of effective refractive index and ray. For the suggested LPWG, the maximum EO modulation could be obtained by putting the tunable electrode on the sides of the waveguide core. With such an arrangement, very small electrode spacing (<10μm)could be designed, thus the LPWG which had a 28dB rejection band could be realized with a very low driving voltage (1.6V) . The investigation for such a grating structure is advantageous for the development of the low voltage highspeed electrooptic LPWG.