[1] [1] INAO S, SATO T, SENTSUI S, et al. Multicore optical fiber[C]//OSA. Proceedings of Optical Fiber Communication Conference. Washington: OSA, 1979: WB1-46-WB1-48.

[3] [3] INAO S. High density multi-core-fiber cable [C]//IWCS. Proceedings of the 28th International Wire & Cable Symposium (IWCS). New Jersey: IWCS, 1979: 370-384.

[4] [4] GAO Y Y, CUI J, JIA J C, et al. Weakly-coupled 7-core-2-LP-mode transmission using commercial SFP+ transceivers enabled by all-fiber spatial multiplexer and demultiplexer[J]. Optics express, 2019, 27(11): 16271-16280.

[5] [5] JUNG Y, HAYES J R, ALAM S U, et al. Multicore fiber fan-in/fan-out device using fiber optic collimators [C]//IEEE. 2017 European Conference on Optical Communication (ECOC). Gothenburg: IEEE, 2017: 1-3.

[6] [6] SHIMAKAWA O, SHIOZAKI M, SANO T, et al. Pluggable fan-out realizing physical-contact and low coupling loss for multi-core fiber [C]//OSA. Proceedings of Optical Fiber Communication Conference. California: OSA, 2013: OM3I. 2-1-OM31.2-3.

[7] [7] YOSHIDA M, HIROOKA T, NAKAZAWA M. Low-loss and reflection-free fused type fan-out device for 7-core fiber based on a bundled structure[J]. Optics express, 2017, 25(16): 18817-18826.

[8] [8] NEUGROSCHL D, KOPP V I, SINGER J, et al. "Vanishing-core" tapered coupler for interconnect applications [C]//International Society for Optics and Photonics. Proceedings of Photonics Packaging, Integration, and Interconnects IX. California: International Society for Optics and Photonics, 2009: 72210G-1-72210G-8.

[9] [9] KOPP V I, PARK J, WLODAWSKI M, et al. Pitch reducing optical fiber array and multicore fiber for space-division multiplexing[C]//IEEE. 2013 IEEE Photonics Society Summer Topical Meeting Series. Waikoloa: IEEE, 2013: 99-100.

[10] [10] LI B R, FENG Z H, TANG M, et al. Experimental demonstration of large capacity WSDM optical access network with multicore fibers and advanced modulation formats [J]. Optics express, 2015, 23(9): 10997-11006.

[11] [11] RYF R, FONTAINE N K, MONTOLIU M, et al. Space-division multiplexed transmission over 3×3 coupled-core multicore fiber[C]//IEEE. OFC, San Francisco: IEEE, 2014: 1-3.

[12] [12] TOTTORI Y, KOBAYASHI T, WATANABE M. Low loss optical connection module for seven-core multicore fiber and seven single-mode fibers[J]. IEEE Photonics Technology Letters, 2012, 24(21): 1926-1928.

[13] [13] UEMURA H, OMICHI K, TAKENAGA K, et al. Fused taper type fan-in/fan-out device for 12 core multi-core fiber[C]//IEEE. Proceedings of 2014 Opto Electronics and Communication Conference and Australian Conference on Optical Fiber Technology. Melbourne: IEEE, 2014: 49-50.

[14] [14] ALVARADO-ZACARIAS J C, ANTONIO-LOPEZ J E, HABIB M S, et al. Low-loss 19 core fan-in/fan-out device using reduced-cladding graded index fibers[C]//OSA. Proceedings of Optical Fiber Communication Conference. San Diego: Optical Society of America, 2019: Th3D. 2-1-Th3D. 2-3.

[15] [15] GAN L, ZHOU J J, SHEN L, et al. Ultra-low crosstalk fused taper type fan-in/fan-out devices for multicore fibers[C]//IEEE. Proceedings of 2019 Optical Fiber Communications Conference and Exhibition (OFC). San Diego: IEEE, 2019: 1-3.