[1] [1] RICHARDSON D J, FINI J M, NELSON L E. Space-division multiplexing in optical fibres[J]. Nature photonics, 2013, 7(5):354-362.

[2] [2] YANG Y, GAO J T, FU S N, et al. Panda type four-core fiber with the efficient use of stress rods[J]. IEEE photonics journal, 2019, 11(5):1-9.

[3] [3] CORSI A, CHANG J H, WANG R H, et al. Highly elliptical core fiber with stress-induced birefringence for mode multiplexing[J]. Optics letters, 2020, 45(10): 2822-2825.

[4] [4] JUNG Y M, KANG Q Y, ZHOU H Y, et al. Low-loss 25.3 km few-mode ring-core fiber for mode-division multiplexed transmission[J]. Journal of lightwave technology, 2017, 35(8):1363-1368.

[5] [5] JIANG S L, MA L, ZHANG Z P, et al. Design and characterization of ring-assisted few-mode fibers for weakly-coupled mode-division multiplexing transmission[J]. Journal of lightwave technology, 2018, 36(23): 5547-5555.

[6] [6] CORSI A, CHANG J H, RUSCH L A, et al. Design of highly elliptical core ten-mode fiber for space division multiplexing with 2×2 MIMO[J]. IEEE photonics journal, 2019, 11(2):1-10.

[7] [7] WANG L X, NEJAD R M, CORSI A, et al. Linearly polarized vector modes:enabling MIMO-free modedivision multiplexing[J]. Optics express, 2017, 25(10): 11736-11748.

[8] [8] YAN H Z, LI S Y, XIE Z Y, et al. Design of PANDA ring-core fiber with 10 polarization-maintaining modes[J]. Photonics research, 2017, 5(1):1-5.

[9] [9] CHEN S, WANG J. Design of PANDA-type elliptical-core multimode fiber supporting 24 fully lifted eigenmodes[J]. Optics letters, 2018, 43(15):3718-3721.

[10] [10] FLEMING J W. Dispersion in GeO2-SiO2 glasses[J]. Applied optics, 1984, 23(24):4486-4493.

[11] [11] LIU Y P, YANG Z Q, ZHAO J, et al. Intrinsic loss of few-mode fibers[J]. Optics express, 2018, 26(2): 2107-2116.

[12] [12] ONISHI M, KASHIWADA T, ISHIGURO Y, et al. High performance dispersion-compensating fibers[J]. Fiber and integrated optics, 1997, 16(3):277-285.