Abstract

We provided a feasible solution for 800-Gb/s per carrier long-distance wavelength division multiplexing (WDM) coherent optical fibre transmission based on offline DSP. We experimentally demonstrate 5-carrier 125-GHz-spacing WDM coherent optical fibre transmission achieving 2000-km transmission distance and 800-Gb/s net bit rate per carrier. We utilized 100-Gbaud truncated probabilistically shaped (TPS) polarization-multiplexed 64QAM format in this work. In terms of advanced components, the high-speed digital-to-analog converter with 35-GHz 3 dB-bandwidth and Raman-amplified ultra-large-area fibre were utilized to achieve higher baud-rate and longer transmission distance. In terms of modulation format, we changed PS to TPS to obtain a more suitable shaping depth, and make the shaped signal better suited to the DSP process of coherent optical communication, including constant modulus algorithm (CMA) equalizer. Besides, our results show that the TPS-64QAM signal with 5-bit/symbol/polarization entropy outperforms the standard-32QAM with a same bit rate by around 1 dB sensitivity gain. Furthermore, we proposed a multiple-input multiple-output (MIMO) Volterra equalizer (VE), which consists of a 1^st-order 2 × 2 MIMO complex-valued widely linear (WL) equalizer and a 2^nd-order real-valued nonlinear equalizer. Our proposed MIMO VE can effectively resolve the impact of In-phase/quadrature (IQ) imbalance and IQ skew, and compensate linear and nonlinear impairments at the same time. We also utilized partial kernel VE to reduce the complexity by retaining part of the 2^nd-order kernels.

112-Gb/s SSB 16-QAM signal transmission over 120-km SMF with direct detection using a MIMO-ANN nonlinear equalizer

Shaohua An, Qingming Zhu, Jingchi Li, Yuye Ling, and Yikai Su
Opt. Express 27(9) 12794-12805 (2019)

Single-carrier 800-Gb/s self-homodyne coherent transmission of DP-16QAM, DP-32QAM, and DP-64QAM with uncooled DFB laser

Min Yang, Guofeng Yan, Shuo Zheng, Zhenyu Wan, Xi Zhang, Yanjun Zhu, Hua Zhang, Chaonan Yao, Yuchen Shao, and Jian Wang
Opt. Express 31(17) 27553-27565 (2023)

A single-channel 1.92 Tbit/s, 64 QAM coherent optical pulse transmission over 150 km using frequency-domain equalization

David Odeke Otuya, Keisuke Kasai, Masato Yoshida, Toshihiko Hirooka, and Masataka Nakazawa
Opt. Express 21(19) 22808-22816 (2013)

Wireless transmission of a 200-m PS-64QAM THz-wave signal using a likelihood-based selection radius-directed equalizer

Junjie Ding, Mingxu Wang, Weiping Li, Bowen Zhu, Feng Wang, Chen Wang, Yanyi Wang, Wen Zhou, Jiao Zhang, Min Zhu, and Jianjun Yu
Opt. Lett. 47(15) 3904-3907 (2022)

42.3 Tbit/s, 18 Gbaud 64 QAM WDM coherent transmission over 160 km in the C-band using an injection-locked homodyne receiver with a spectral efficiency of 9 bit/s/Hz

Takashi Kan, Keisuke Kasai, Masato Yoshida, and Masataka Nakazawa
Opt. Express 25(19) 22726-22737 (2017)