Cui Jian, Deng Yu, Liu Zhuo, Hao Bin, Wu Chao, Tan Daiwei, Jiang Ming, Zhang Leimin, Chen Zhangyuan, He Yongqi, Li Juhao, Wan Qi
Appl Opt. 2024 May 1;63(13):3399-3405. doi: 10.1364/AO.516866.
Weakly coupled mode-division multiplexing (MDM) transmission over legacy laid multimode fiber (MMF) has great economic efficiency and can enormously enhance the capacity of short-reach optical interconnections. In order to be compatible with cost-efficient intensity-modulation/direct-detection (IM/DD) transceivers, weakly coupled mode-group demultiplexers that can simultaneously receive each mode group of MMFs are highly desired. In this paper, we propose a scalable low-modal-crosstalk mode-group demultiplexer over MMF based on multiplane light conversion (MPLC). Multiple input Hermite-Gaussian (HG) modes of MMF are first converted to bridging modes that are composed of modes distributed as a right-angle triangle in Cartesian coordinates, and then each mode belonging to a degenerate mode group is mapped to different overlapped modes with vertical orientation for simultaneous detection. With the help of bridging modes, the MPLC-based mode-group demultiplexer can efficiently demultiplex all mode groups in standard MMFs with less than 20 phase masks. A nine-mode-group demultiplexer is further designed for demonstration, and simulation results show that the MPLC-based demultiplexer achieves low modal crosstalk of lower than -22.3 at 1550 nm and lower than -17.9 over the C-band for all the nine mode groups with only 16 phase masks.
在传统铺设的多模光纤（MMF）上进行弱耦合模式分割复用（MDM）传输具有很高的经济效益，并且可以极大地提高短距离光互连的容量。为了与具有成本效益的强度调制/直接检测（IM/DD）收发器兼容，非常需要能够同时接收MMF的每个模式组的弱耦合模式组解复用器。在本文中，我们提出了一种基于多平面光转换（MPLC）的、可扩展的、低模态串扰的MMF模式组解复用器。MMF的多个输入厄米高斯（HG）模式首先被转换为桥接模式，这些桥接模式由笛卡尔坐标中呈直角三角形分布的模式组成，然后属于简并模式组的每个模式被映射到具有垂直方向的不同重叠模式以进行同时检测。借助桥接模式，基于MPLC的模式组解复用器可以用少于20个相位掩膜有效地解复用标准MMF中的所有模式组。进一步设计了一个九模式组解复用器用于演示，仿真结果表明，基于MPLC的解复用器在1550 nm处实现了低于-22.3的低模态串扰，并且在C波段上，对于所有九个模式组，仅用16个相位掩膜就实现了低于-17.9的低模态串扰。
