Abstract

Coherent optical systems for short-reach links have seen a boost in their popularity with the standardization of 400ZR. These systems need to be cost and power-efficient, while coping with the ever increase in traffic demand. The use of probabilistic constellation shaping (PCS) can help meet these demands, since it reduces the gap to the channel capacity. However, studies concerning PCS typically include optical amplification; therefore, its gain in amplifier-less systems has been somewhat uncertain. In this work, we focus on an amplifier-less coherent optical link employing PCS, reducing both power consumption and system complexity due to the removal of the amplifier. We employ PCS for different modulation orders and bit rates, while optimizing several key parameters such as the FEC coding overhead, modulation depth and clipping. With this comprehensive study, we demonstrate by system simulation and experimental validation that PCS is beneficial even for amplifier-less systems, since it introduces residual gains while allowing higher flexibility in defining the net bit rate in a system with fixed baud rate.

Principle and strategy of using probabilistic shaping in a flexible coherent passive optical network without optical amplifiers

Sizhe Xing, Guoqiang Li, An Yan, Wangwei Shen, Zhongya Li, Jiaye Wang, Jianyang Shi, Zhixue He, Nan Chi, and Junwen Zhang
J. Opt. Commun. Netw. 15(8) 507-517 (2023)

Secure turbulence-resistant coherent free-space optical communications via chaotic region-optimized probabilistic constellation shaping

Tingwei Wu, Wei Zeng, Yejun Liu, Song Song, Lun Zhao, Chen Chen, Chongfu Zhang, and Lei Guo
Opt. Lett. 48(3) 684-687 (2023)

Discrete multitone transmission for underwater optical wireless communication system using probabilistic constellation shaping to approach channel capacity limit

Xiaojian Hong, Chao Fei, Guowu Zhang, Ji Du, and Sailing He
Opt. Lett. 44(3) 558-561 (2019)

Constellation size for probabilistic shaping under the constraint of limited ADC resolution

Qiulin Zhang and Chester Shu
Opt. Lett. 44(23) 5820-5823 (2019)

Demonstration of flexible access in a rate-adaptive visible light communication system with constellation probabilistic shaping

Sizhe Xing, Fangchen Hu, Guoqiang Li, Junwen Zhang, Nan Chi, Zhixue He, and Shaohua Yu
Opt. Express 29(21) 34441-34451 (2021)