波导耦合器是组成光纤传感系统和光纤通信系统光收发组件及模块的重要元器件，是实现光收发模块一体化光电集成的基础。给出了一种用光纤陀螺系统的X型四端口波导耦合器的工作原理，采用有效折射率法和BPM(Beam propagation method)法建立了耦合器的数学模型，计算并分析了耦合器尺寸在尽可能小的情况下和在满足单模传输的条件下耦合器的耦合系数、有效耦合长度、分光比以及回波损耗等参数之间的关系，并对其关键技术进行了系统的研究。仿真结果表明，所设计的波导耦合器在低损耗情况下分光比可达到50%∶50%，耦合器全长为33．5mm，输入输出波导间距为410μm，芯层截面积为6μm×6μm。

Waveguide coupler is an important element of optical integrated transceiver module,making up of the optical fiber sensor systems and optical communication systems. It is the basic realizing one-chip hybridly integrated optical transceiver module. An optical waveguide coupler,specially used for FOG and its principle are presented. Based on effective index method (EIM) and beam propagation method(BPM),the mathematic model of waveguide coupler is established. Under the conditions of possible miniaturization and single-mode optical beam transmitting of waveguide coupler,coupling ratio,effective coupling length,returning loss and their relationships are calculated and analyzed. Its key technology is systematically investigated. On the basis of analysis of emulating results,the size of optical waveguide coupler with division radio 50%:50% and low loss can achieve 33.5 ×0.41mm² ,and the size of the core is 6×6μm².