Low-modal-crosstalk orthogonal combine reception for degenerate modes in IM/DD MDM transmission

• Published in: Optics express Vol. 31; no. 5; pp. 8586 - 8594
• Main Authors: Cui, Jian, Gao, Yuyang, Huang, Shuailuo, Yu, Jinyi, Shen, Lei, Zhang, Lei, Yan, Changkun, Yang, Liubo, Wang, Ruichun, He, Yongqi, Chen, Zhangyuan, Li, Juhao
• Format: Journal Article
• Language: English
• Published: United States 27.02.2023
• ISSN: 1094-4087; 1094-4087
• DOI: 10.1364/OE.482879

Weakly-coupled mode division multiplexing (MDM) techniques supporting intensity modulation and direct detection (IM/DD) transmission is a promising candidate to enhance the capacity of short-reach applications such as optical interconnections, in which low-modal-crosstalk mode multiplexers/demultiplexers (MMUX/MDEMUX) are highly desired. In this paper, we firstly propose an all-fiber low-modal-crosstalk orthogonal combine reception scheme for degenerate linearly-polarized (LP) modes, in which signals in both degenerate modes are firstly demultiplexed into the LP mode of single-mode fibers, and then are multiplexed into mutually orthogonal LP and LP modes of a two-mode fiber for simultaneous detection. Then a pair of 4-LP-mode MMUX/MDEMUX consisting of cascaded mode-selective couplers and orthogonal combiners are fabricated with side-polishing processing, which achieve low back-to-back modal crosstalk of lower than -18.51 dB and insertion loss of lower than 3.81 dB for all the 4 modes. Finally, a stable real-time 4 modes × 4λ × 10 Gb/s MDM-wavelength division multiplexing (WDM) transmission over 20-km few-mode fiber is experimentally demonstrated. The proposed scheme is scalable to support more modes and can pave the way to practical implementation of IM/DD MDM transmission applications.