设计具有宽带性能的偏振无关1×3光功分器,采用离子辅助沉积方法调节三明治结构芯层SiN_x的折射率,使得正交偏振模的拍长相等而实现偏振无关;梯形多模干涉波导与锥形波导的组合可实现器件宽带宽、低损耗及良好的分光均匀性。运用有限时域差分法进行建模仿真及参数优化,结果表明:器件的多模干涉波导长度仅为13.2 μm,附加损耗低于0.07 dB,不均匀度低于0.03 dB,0.5 dB带宽高达255 nm,可覆盖S、C、L、U以及部分E波段,在未来集成光学系统中具有较高的应用价值。

We proposed a polarization-insensitive 1×3 optical power splitter with broadband performance. Ion assisted deposition was used to change the refractive index of the core SiN_x in a sandwiched structure, so that the beat lengths of the orthogonal polarization modes were equal and thus polarization insensitivity was achieved. A combined structure of trapezoidal multimode interference waveguide and tapered waveguide was introduced to realize broad bandwidth, low loss, and good beam splitting uniformity. Furthermore, a finite-difference time-domain method was applied to simulation and optimization, and the results demonstrate that the length of the multimode interference waveguide is only 13.2 μm; the excess loss and imbalance of the splitter are lower than 0.07 dB and 0.03 dB, respectively. In addition, the 0.5 dB-loss bandwidth is as high as 255 nm, which can cover S, C, L, U, and part of E bands. Therefore, the proposed splitter has potential application value in the future integrated optical systems.