Integrated photonics enables the miniaturization of bulk optical components for biosensing applications such as optical coherence tomography (OCT) and is therefore promising for future lab-on-chip solutions. Here, we report the design and simulation of a compact low loss broadband beam splitter with arbitrary coupling ratios on silicon nitride platform for OCT systems. The reported coupler uses asymmetric waveguide-based phase control section for 10:90, 20:80, 30:70, 40:60, and 50:50 splitting ratios and is broadband over 100 nm with the central wavelength of 850 nm. The couplers are realized for transverse electric, transverse magnetic, and fully vectorial modes, and maximum excess loss for all mode types is reported to be less than 0.19 dB. The design tolerance of waveguide width and thickness of the designed coupler is further calculated and is within fabrication limit.

集成光子技术可实现用于生物传感应用（例如光学相干断层扫描（OCT））的整体光学组件的小型化，因此有望用于未来的芯片实验室解决方案。在这里，我们报告用于OCT系统的氮化硅平台上具有任意耦合比的紧凑型低损耗宽带分束器的设计和仿真。报道的耦合器使用基于非对称波导的相位控制部分以实现10：90、20：80、30：70、40：60和50:50的分光比，并且在100 nm处具有850 nm的中心波长宽带。耦合器是针对横向电，横向磁和全矢量模式实现的，据报道，所有模式类型的最大过量损耗均小于0.19 dB。