为了对飞秒激光加工微纳米尺度波导器件的可行性进行分析，采用有限差分光束传输法对余弦型Y波导合波器的耦合夹角大小对合路光场的影响进行了仿真模拟，分析了光场强度、分支角度以及损耗等之间的关系，得到当耦合夹角为0.6rad时，输入光场相互隔离，附加损耗低至0.45dB，传输效率接近90%的结果。结果表明，在石英玻璃这种高损伤阈值的材料中利用飞秒激光直写制备光合波器件时，预先对加工的微纳器件进行仿真模拟，在微纳光子集成及微纳米光波导中具有很重要的意义。

In order to analyze the feasibility of machining micro- or nanophotonic devices using femtosecond laser, effect of the coupling angles on the coupled beam field of cosine style of Y combiners was simulated based on the optical beam propagation equation solved by finite difference iterative, and the relationship among field intensity, coupling angle and transmission loss was analyzed. The results show that when the coupling angle is 0.6rad and the incident fields are completely isolated, the transmission loss is as low as 0.45dB, and the transmission efficiency is as high as 90%. The numerical simulation provides a basic preanalysis for fabricating opto-combiners in fused silica with high damage threshold by femtosecond laser. Furthermore, it has great significance for micromaching micro- or nanophotonic and waveguide-based devices using femtosecond laser.