Polarization rotator-splitters (PRSs) are crucial components for controlling the polarization states of light in classical and quantum communication systems. We design and experimentally demonstrate a broadband PRS based on the lithium niobate on insulator (LNOI) platform. Both the rotator and splitter sections are based on adiabatically tapered waveguide structures, and the whole device only requires a single etching step. We show efficient PRS operation over an experimentally measured bandwidth of 130 nm at telecom wavelengths, potentially as wide as 500 nm according to simulation prediction, with relatively low polarization crosstalks of $\sim -10\mathrm{dB}$. Our PRS is highly compatible with the design constraints and fabrication processes of common LNOI photonic devices, and it could become an important element in future LNOI photonic integrated circuits.

中文翻译：

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基于铌酸锂绝缘体平台的宽带绝热极化旋转分路器

偏振旋转分束器 (PRS) 是控制经典和量子通信系统中光偏振态的关键组件。我们设计并实验证明了一种基于绝缘体上铌酸锂 (LNOI) 平台的宽带 PRS。旋转器和分路器部分都基于绝热锥形波导结构，整个设备只需要一个蚀刻步骤。我们在电信波长的 130 nm 实验测量带宽上展示了有效的 PRS 操作，根据模拟预测可能高达 500 nm，具有相对较低的偏振串扰$\sim -10\mathrm{D\; b}$. 我们的 PRS 与常见 LNOI 光子器件的设计约束和制造工艺高度兼容，它可能成为未来 LNOI 光子集成电路的重要元素。