A compact and broadband polarization beam splitter (PBS) is proposed based on an asymmetric directional coupler consisting of a hybrid plasmonic waveguide and a ridge waveguide on lithium-niobate-on-insulator. Due to the surface plasma polariton (SPP) effect, the phase-matching condition is satisfied for transverse electric polarization, whereas the transverse magnetic polarization has a significant phase mismatch by choosing reasonable widths of both waveguides. A short ( ∼ 28 μm long) PBS is designed while the gap width is chosen to be 200 nm to make it easy to fabricate. Numerical simulations show that the designed PBS has a broad bandwidth (>130 nm) for an extinction ratio of >15 dB and a large fabrication tolerance for the variation of the waveguide width (over ± 50 nm).

中文翻译：

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使用混合等离子体波导的铌酸锂绝缘体上的紧凑型宽带偏振分束器

基于由混合等离子体波导和铌酸锂绝缘体上的脊波导组成的非对称定向耦合器，提出了一种紧凑型宽带偏振分束器 (PBS)。由于表面等离子体极化子（SPP）效应，横向电极化满足相位匹配条件，而横向磁极化通过选择合理的两个波导宽度具有显着的相位失配。设计了一个短的（~ 28 μm 长）PBS，同时选择间隙宽度为 200 nm 以使其易于制造。数值模拟表明，设计的 PBS 具有较宽的带宽 (>130 nm)，消光比 >15 dB，并且对波导宽度的变化（超过 ± 50 nm）具有较大的制造公差。