[5] [5] Houtsma V，Van Veen D，Harstead E. Recent progress on standardization of next-generation 25，50，and 100 G EPON［J］. JournalofLightwaveTechnology，2017，35(6): 1228-1234.

[6] [6] YGuo，YYin，YSong，et al. Demonstrationof25Gbit/sperchannelNRZtransmissionwith35dBpowerbudget using 25G Ge/Si APD for next generation 100G-PON［C］. 2017 Optical Fiber Communications Conference and Exhibition(OFC)，IEEE，2017，1-3.

[7] [7] S Li，Z Ye，N Cheng，et al. Demonstration of a real-time 25-Gb/s TDM-PON system with 25-Gb/s downstream basedonopticalduobinaryand10-Gb/sburst-modeupstreambasedonNRZ［C］.2016OpticalFiberCommunications ConferenceandExhibition(OFC)，IEEE，2016，1-3.

[14] [14] S -R Moon，H. -S. Kang，H. Rha，et al. C-band PAM-4 signal transmission using soft-output MLSE and LDPC code［J］. OpticalExpress，2019，(27): 110-120.