A novel compact polarization beam splitter (PBS) based on a triple-waveguide directional coupler is presented. Among these three waveguides, the middle one is regarded as an input where the contrast of effective refractive index between fundamental modes is enhanced with dielectric-loaded waveguide. Confined into the waveguides with coupling lengths of $8.3~\mu \text{m}$ (TM) and $9.9~\mu $ m (TE) on both sides, the two fundamental modes are separately coupled. In virtue of the separated coupling structure, a high polarization extinction ratio (PER) of 45.6 dB together with a low insertion loss (< 0.3 dB) for TE mode, and meanwhile a moderate PER of 20.0 dB with an insertion loss of (< 0.1 dB) for TM mode are achieved at around $1.55~\mu \text{m}$ . Furthermore, the operation bandwidth of this PBS, during which the PER is higher than 40 dB, is up to 80 nm for TE mode.

中文翻译：

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分离耦合实现的高消光比偏振分束器

提出了一种基于三波导定向耦合器的新型紧凑型偏振分束器 (PBS)。在这三个波导中，中间的一个被认为是输入，其中基模之间的有效折射率对比度通过介电加载波导增强。被限制在耦合长度为 $8.3~\mu \text{m}$ (TM) 和 $9.9~\mu $ m (TE) 两侧，两个基模分别耦合。凭借分离耦合结构，TE 模式具有 45.6 dB 的高偏振消光比 (PER) 和低插入损耗 (< 0.3 dB)，同时具有 20.0 dB 的中等 PER，插入损耗 (< 0.1 dB) 对于 TM 模式在大约 $1.55~\mu \text{m}$ . 此外，该 PBS 的操作带宽在 PER 高于 40 dB 期间，对于 TE 模式高达 80 nm。