Clone-comb-enabled high-capacity digital-analogue fronthaul with high-order modulation formats

• Published in: Nature photonics Vol. 17; no. 11; pp. 1000 - 1008
• Main Authors: Zhang, Chenbo, Zhu, Yixiao, He, Bibo, Lin, Jingjing, Liu, Rongwei, Xu, Yicheng, Yi, Lilin, Zhuge, Qunbi, Hu, Weiwei, Hu, Weisheng, Chen, Zhangyuan, Xie, Xiaopeng
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.11.2023; Nature Publishing Group
• Subjects: 639/624/1075/1081; 639/624/1075/187; 639/624/1111/1112; Amplitudes; Applied and Technical Physics; Bandwidths; Coherence; Data transmission; Frequency dependence; Internet access; Modulation; Optical fibers; Optical frequency; Oscillators; Photonics; Physics; Physics and Astronomy; Quadratures; Quantum Physics; Radio; Signal processing; Signal to noise ratio; Wireless access points; Wireless communications; Wireless networks
• ISSN: 1749-4885; 1749-4893
• DOI: 10.1038/s41566-023-01273-2

Access to the internet by mobile terminals relies on the transmission of information from the optical fibre backbone to wireless networks. Fronthaul, as the last mile of fibre-wireless convergence, determines the overall transmission performance in terms of capacity and fidelity. Orders-of-magnitude increases in both bandwidth and signal-to-noise ratio (SNR) are urgently desired to cope with the large growth in wireless traffic. Here we demonstrate a self-homodyne digital-analogue radio-over-fibre fronthaul using cloned optical frequency combs that meets these needs. The approach simultaneously supports an unprecedented 14.1 Tb s −1 common public radio interface equivalent data rate and a 1,024 quadrature-amplitude-modulated format. The clone-comb configuration, which possesses the properties of frequency and phase locking, is the key to enabling a high-performance coherent digital-analogue radio-over-fibre system. Besides exploiting the quadruple capacity for a single channel thanks to coherent detection, the clone-comb approach can also provide multiple parallel channels concurrently, boosting the overall data throughput. We further demonstrate the potential of the technique, showing its ability to transmit 65,536 quadrature-amplitude-modulated signals and a data rate of 32.8 Tb s −1 . Our architecture is promising for fibre-based and free-space optical fronthaul, bringing full-band and coherent-lite access networks into reach. The use of clone combs provides very high-capacity radio-over-fibre data transmission with high-order modulation formats.