介绍了光纤陀螺的工作原理，依据与惯性空间作相对转动导致的Sagnac效应，对光纤陀螺的关键器件即集成光学调制器进行了分析；运用导出的基本公式，对研制光纤陀螺普遍采用的铌酸锂Y分支集成电光波导调制器的驱动电压和调制带宽参数进行了计算，计算结果为该调制器的设计提供了可靠数据。关 键 词 光纤陀螺; Y分支调制器; 集成光学; 铌酸锂Abstract A fiber-optic gyro is a kind of optical fiber sensor for the angular velocity. In this paper, the fundamental principle of fiber-optic gyro based on Sagnac effect is reviewed, and the integrated optical phase modulator, which is a key device of the gyro and is our main task in the work, are analysed. According to the yielded equations, the drive voltage and frequency bandwidth in modulation of fiber-optic gyro are calculated, and the calculation results can be contributed to a design of the modulator used in fiber-optic gyro.Key words fiber-optic gyro; Y-branch modulator; integrated optics; lithium niobate