Abstract

The performance of high-speed intensity modulation direct detection (IM-DD) transmissions is severely degraded by the linear inter-symbol interference (ISI), due to both bandwidth-constrained optoelectrical components and the chromatic dispersion (CD). Meanwhile, nonlinear ISI due to intensity modulation and square-law detection can further deteriorate the IM-DD system performance significantly. Here, we first propose three metrics to quantify those impairments in IM-DD transmissions. Then, we compare both the BER performance and computational complexity of different DSP schemes to enable short-reach high-speed IM-DD transmissions with severe bandwidth constraint, using a C-band PAM-4 experimental test-bed with an end-to-end 10-dB bandwidth of 17 GHz. Those DSP schemes include receiver-side feedforward equalization (FFE), receiver-side Volterra filter equalization (VFE), transmitter-side Tomlinson-Harashima precoding (THP) together with receiver-side FFE, transmitter-side THP together with receiver-side VFE, channel-shortening filter (CSF) together with maximum likelihood sequence estimation implemented with linear branch metrics (MLSE-LI-BM), and CSF together with MLSE implemented with nonlinear branch metrics (MLSE-NL-BM). Our experimental results indicate that, only the combination of CSF and MLSE-NL-BM enables a 112 Gbit/s transmission over 5 km fiber at the KP4-FEC threshold, but with an increased computational complexity.

C-band 200 Gbit/s/λ PAM-4 transmission over 2-km SSMF using look-up-table pre-distortion combined with nonlinear Tomlinson-Harashima pre-coding

Yucheng Tu, Hailin Yang, Gai Zhou, Meng Xiang, Songnian Fu, Ming Tang, Yuwen Qin, and Luming Zhao
Opt. Express 30(9) 15416-15427 (2022)

56-Gb/s/λ C-band DSB IM/DD PAM-4 40-km SSMF transmission employing a multiplier-free MLSE equalizer

Zhuo Chen, Junyuan Nie, Shenmao Zhang, Qi Yang, Xiaoxiao Dai, Lei Deng, Mengfan Cheng, and Deming Liu
Opt. Express 30(7) 11275-11287 (2022)

Decision region partition aided MLSE for O-band 65-Gbaud PAM-4 system over 40-km transmission with a severe bandwidth constraint

Weihao Ni, Fan Li, Mingzhu Yin, Zhiwei Chen, Wei Wang, Dongdong Zou, Yi Cai, Qi Sui, and Zhaohui Li
Opt. Lett. 47(17) 4387-4390 (2022)

Transmitter and receiver DSP for 112 Gbit/s PAM-4 amplifier-less transmissions using 25G-class EML and APD

Jiahao Huo, Xian Zhou, Kang Ping Zhong, Jiajing Tu, Jinhui Yuan, Changjian Guo, Keping Long, Changyuan Yu, Alan Pak Tao Lau, and Chao Lu
Opt. Express 26(18) 22673-22686 (2018)

Experimental study of performance enhanced IM/DD transmissions combining 4D Trellis coded modulation with precoding

Meng Xiang, Zhenping Xing, Xueyang Li, Eslam El-Fiky, Mohamed Morsy-Osman, Qunbi Zhuge, and David V. Plant
Opt. Express 26(25) 32522-32531 (2018)