通过束传播方法(BPM)模拟了SiO₂基掩埋式波导结构多模干涉(MMI)型分束器的反射性能，模拟结果表明，MMI工作在分束模式时存在最优的多模干涉长度实现最大输出和最小反射，而在合束模式下实现最大输出时反射也达到最大，这是由自映象原理决定的。SiO₂基掩埋式波导结构MMI分束器对反射具有良好的抑制作用，其最大反射功率为－60dB。分析表明，多模干涉区末端的界面反射率决定了器件的反射强弱，SiO₂基掩埋式波导的界面反射率非常低，这是其低反射的原因。

The BPM method was adopted to simulate the reflection of the silica based buried waveguide MMI. The simulation results indicated that the transmitted and reflected intensity amounted to optimum value at the same length of multimode region when MMI worked as a splitter,however,when MMI worked as a combiner,the reflected and transmitted intensity amounted to the maximum value at the same length of multimode region,which is due to self-image principle. The silica based buried MMI suppressed reflection perfectly,the most reflection intensity of which was-60dB. The further analysis show that the reflection of the interface at the end of the multimode region is the deterrnining factor to the reflection property of the whole device. The less reflection of the interface at the end of multimode region in the silica based buried MMI is the source of its low reflection.