[3] [3] CHANG DI，ZAK E，PELOUCH W，et al. 100G unrepeatered transmission over 626.8 km with a span loss in excess of 100 dB[EB/OL].[2021-04-16]. https://www.osapublishing.org/viewmedia.cfm?uri=ACPC-2015-AM4A.2&seq=0.

[4] [4] BISSESSUR H, BASTIDE C, ETIENNE S, et al. 24 Tb/s Unrepeatered C-band transmission of real-time processed 200 Gb/s PDM-16-QAM over 349 km[EB/OL].[2021-04-16]. https://www.osapublishing.org/abstract.cfm?URI=OFC-2017-Th4D.2.

[5] [5] XU Jian, LI Ming, SUN Shujuan, et al. Record 579.5 km unrepeatered 2.5Gb/s transmission with a span Loss of 96.8 dB by coherent receiving technology[EB/OL].[2021-04-16]. https://kns.cnki.net/KCMS/detail/detail.aspx?dbcode=IPFD&filename=ZCSD201805002040.

[6] [6] XU Jian, YU Jiekui, HU Qianggao, et al. Longest-ever unrepeatered transmission over 713.2km of 2.5Gb/s with a span loss in excess of 111dB[EB/OL].[2021-04-16]. https://ieeexplore.ieee.org/document/8699351.

[7] [7] XU J, YU J, HU Q, et al. 50G BPSK, 100G SP-QPSK, 200G 8QAM, 400G 64QAM ultra long single span unrepeatered transmission over 670.64km, 653.35km, 601.93km and 502.13km respectively[EB/OL].[2021-04-16]. https://www.researchgate.net/publication/331333963_50G_BPSK_100G_SP-QPSK_200G_8QAM_400G_64QAM_ultra_long_single_span_unrepeatered_transmision_over_67064km_65335km_60193km_and_50213km_respectively: