High performance InP-based polarization beam splitters (PBSs) with a symmetrical Mach–Zehnder interferometer (MZI) are theoretically and experimentally demonstrated. The p-i-n waveguide is exploited to employ the phase shifters in the two arms of the MZI. Injection current and reverse bias inducing electro-optic (EO) effects in each of the MZI arms are analysed in detail when the waveguides are aligned along both the [011] and $[ {01\bar{1}} ]$ directions. Results indicate that the birefringence from reverse bias help to realize the PBS combining with the polarization-independent carrier-induced refractive index change from the injection current. Theoretical prediction shows that the polarization extinction ratio (PER) is over 35 dB at 1550 nm for the PBSs with the waveguides aligned along both directions. Furthermore, the PBS with the waveguides aligned along the [011] direction can be adjusted more easily to work at the best operating point and get the higher birefringence which requires lower reverse bias exhibiting better performance across the C-band compared with the $[ {01\bar{1}} ]$ direction. The fabricated PBSs exhibit a PER over 19 dB (14 dB) in the wavelength range from 1525 to 1570 nm with one arm injected of 2.88 mA (0.2 mA) current and the other arm reversed biased at 5.63 V (7.89 V) when the waveguides aligned along the [011] ($[ {01\bar{1}} ]$) direction. The PER of both PBSs is expected to be 20 dB across the C-band with the help of a birefringence contribution arising from inserting waveguide arms of different widths.

中文翻译：

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具有反向偏置和注入电流的高性能基于 InP 的偏振分束器

具有对称 Mach-Zehnder 干涉仪 (MZI) 的高性能基于 InP 的偏振分束器 (PBS) 在理论上和实验上得到了证明。针式波导用于在 MZI 的两个臂中使用移相器。当波导沿 [011] 和$[ {01\bar{1}} ]$方向。结果表明，反向偏压产生的双折射有助于实现 PBS 与偏振无关的载流子引起的注入电流引起的折射率变化相结合。理论预测表明，波导沿两个方向对齐的 PBS 在 1550 nm 处的偏振消光比 (PER) 超过 35 dB。此外，波导沿 [011] 方向对齐的 PBS 可以更容易地调整以在最佳工作点工作并获得更高的双折射，这需要更低的反向偏置，与 C 波段相比表现出更好的性能$[ {01\bar{1}} ]$方向。制造的 PBS 在 1525 至 1570 nm 的波长范围内表现出超过 19 dB (14 dB) 的 PER，其中一个臂注入 2.88 mA (0.2 mA) 电流，另一臂在波导时反向偏置为 5.63 V (7.89 V)沿 [011] ($[ {01\bar{1}} ]$） 方向。在插入不同宽度的波导臂所产生的双折射贡献的帮助下，两个 PBS 的 PER 在 C 波段上预计为 20 dB。