With the amplitude, time, wavelength/frequency, phase, and polarization/spin parameter dimensions of the light wave/photon almost fully utilized in both classical and quantum photonic information systems, orbital angular momentum (OAM) carried by optical vortex modes is regarded as a new modal parameter dimension for further boosting the capacity and performance of the systems. To exploit the OAM mode space for such systems, stringent performance requirements on a pair of OAM mode multiplexer and demultiplexer (also known as mode sorters) must be met. In this work, we implement a newly discovered optical spiral transformation to achieve a low-cross-talk, wide-optical-bandwidth, polarization-insensitive, compact, and robust OAM mode sorter that realizes the desired bidirectional conversion between seven co-axial OAM modes carried by a ring-core fiber and seven linearly displaced Gaussian-like modes in parallel single-mode fiber channels. We further apply the device to successfully demonstrate high-spectral-efficiency and high-capacity data transmission in a 50-km OAM fiber communication link for the first time, in which a multi-dimensional multiplexing scheme multiplexes eight orbital-spin vortex mode channels with each mode channel simultaneously carrying 10 wavelength-division multiplexing channels, demonstrating the promising potential of both the OAM mode sorter and the multi-dimensional multiplexed OAM fiber systems enabled by the device. Our results pave the way for future OAM-based multi-dimensional communication systems.

中文翻译：

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紧凑和高性能的涡旋模式分选器，用于多维复用光纤通信系统

由于经典和量子光子信息系统几乎都充分利用了光波/光子的振幅，时间，波长/频率，相位和偏振/自旋参数尺寸，因此，光学涡旋模式所携带的轨道角动量（OAM）被认为是一个新的模态参数尺寸，可以进一步提高系统的容量和性能。为了为此类系统开发OAM模式空间，必须满足一对OAM模式复用器和解复用器（也称为模式分类器）的严格性能要求。在这项工作中，我们实施了新发现的光学螺旋变换，以实现低串扰，宽带宽，对偏振不敏感，紧凑，强大的OAM模式分选器，可在环形单芯光纤所承载的七个同轴OAM模式与并行单模光纤通道中的七个线性位移高斯型模式之间实现所需的双向转换。我们进一步应用该设备首次成功地演示了在50公里OAM光纤通信链路中的高光谱效率和高容量数据传输，其中多维复用方案将八个轨道自旋涡旋模式信道与每个模式信道同时承载10个波分复用信道，展示了该设备支持的OAM模式分类器和多维复用OAM光纤系统的潜力。我们的结果为未来基于OAM的多维通信系统铺平了道路。