# Automatic Power Optimization of a 44 Tbit/s Real-Time Transmission System over 1900 km G.654.E Fiber and Widened C+L Erbium-Doped Fiber Amplifiers Utilizing 400 Gbit/s Transponders

^{1}

^{2}

^{3}

^{*}

## Abstract

**:**

## 1. Introduction

## 2. Principle

_{k}, can be represented as:

_{ik}represents the Raman gain coefficient between the i-th channel and the k-th channel, A

_{eff}represents the effective area, and α is the fiber attenuation coefficient. Assuming that the Raman gain spectrum is a triangular gain spectrum, it can be calculated that for a certain length of fiber, the power transmitted to different wavelengths at distance z can be expressed as:

_{0}represents the total optical input power and S(0,λ) represents the power input from the optical fiber to each channel. Moreover, the effective length L

_{eff}and Raman transfer coefficient β can be calculated as follows:

_{0}represents the average gain of the OA, GainTilt is the gain slope, and f

_{ref}is the reference frequency. Here, the G

_{0}parameters at the C band and L band are, respectively, set as 22 dB and 22.5 dB to compensate for span losses, while the GainTilt parameters of the C band and L band are, respectively, set as −1.5 dB and −1 dB, which are the same as the default values of the OAs in the experiment. The f

_{ref}is set as the center frequency of each band. The entire setup is defined as one optical multiplex section (OMS).

_{m}(dB/THz), to compensate for the power transfer, the slope compensation amount for each OA can be expressed as follows:

_{2}is the target power of the receiver side and P

_{0}is the actual received power.

## 3. Experimental Setup

## 4. Results and Discussions

^{−2}).

## 5. Conclusion

## Author Contributions

## Funding

## Institutional Review Board Statement

## Informed Consent Statement

## Data Availability Statement

## Conflicts of Interest

## References

- Omdia. Global Fiber Development Index Analysis: 2020 Report. Available online: https://omdia.tech.informa.com/marketing/campaigns/broadband-global-fiber (accessed on 22 October 2020).
- Wang, F.; Gao, R.; Li, Z.; Zhang, Q.; Yu, C.; Tian, Q.; Wang, Y.; Xin, X. Fast linear optical sampling with high repetition-frequency using fiber delay lines. Opt. Express
**2022**, 30, 32895–32907. [Google Scholar] [CrossRef] [PubMed] - Winzer, P.J.; Neilson, D.T.; Chraplyvy, A.R. Fiber-optic transmission and networking: The previous 20 and the next 20 years [Invited]. Opt. Express
**2018**, 26, 24190–24239. [Google Scholar] [CrossRef] [PubMed] - Zhong, K.; Zhou, X.; Huo, J.; Yu, C.; Lu, C.; Lau, A.P.T. Digital Signal Processing for Short-Reach Optical Communications: A Review of Current Technologies and Future Trends. J. Light. Technol.
**2018**, 36, 377–400. [Google Scholar] [CrossRef] - Winzer, P.J. Scaling Optical Networks through SDM Technologies. In Proceedings of the 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC), Fukuoka, Japan, 7–11 July 2019; p. WB1-1. [Google Scholar]
- Zhou, X.; Urata, R.; Liu, H. Beyond 1 Tb/s Intra-Data Center Interconnect Technology: IM-DD or Coherent? J. Light. Technol.
**2020**, 38, 475–484. [Google Scholar] [CrossRef] - Essiambre, R.-J.; Kramer, G.; Winzer, P.J.; Foschini, G.J.; Goebel, B. Capacity Limits of Optical Fiber Networks. J. Light. Technol.
**2010**, 28, 662–701. [Google Scholar] [CrossRef] - Bosco, G. Advanced Modulation Techniques for Flexible Optical Transceivers: The Rate/Reach Tradeoff. J. Light. Technol.
**2019**, 37, 36–49. [Google Scholar] [CrossRef] - Le Gac, D.; Bendimerad, D.; Demirtzioglou, I.; De Jauregui Ruiz, I.F.; Lorences-Riesgo, A.; El Dahdah, N.; Gallet, A.; Elfaiki, H.; Yu, S.; Gao, G.; et al. 63.2Tb/s Real-time Transmission Through Discrete Extended C- and L-Band Amplification in a 440km SMF Link. In Proceedings of the 2021 European Conference on Optical Communication (ECOC), Bordeaux, France, 13–16 September 2021. [Google Scholar]
- Hamaoka, F.; Saito, K.; Masuda, A.; Taniguchi, H.; Sasai, T.; Nakamura, M.; Kobayashi, T.; Kisaka, Y. 112.8-Tb/s Real-Time Transmission over 101 km in 16.95-THz Triple-Band (S, C, and L Bands) WDM Configuration. In Proceedings of the 27th OptoElectronics and Communications Conference (OECC) and 2022 International Conference on Photonics in Switching and Computing (PSC), Toyama, Japan, 3–7 July 2022. paper PDP-A-3. [Google Scholar]
- Frignac, Y.; Gac, D.L.; Riesgo, A.L.; Godard, L.; Landero, S.E.; Zhao, X.; Pincemin, E.; Guyader, B.L.; Brochier, N.; Guo, Q.; et al. Record 158.4 Tb/s Transmission over 2 × 60 km Field SMF Using S+C+L 18THz-Bandwidth Lumped Amplification. In Proceedings of the European Conference on Optical Communication (ECOC), Glasgow, UK, 1–5 October 2023. [Google Scholar]
- Soma, D.; Kato, T.; Beppu, S.; Elson, D.J.; Muranaka, H.; Irie, H.; Okada, S.; Tanaka, Y.; Wakayama, Y.; Yoshikane, N.; et al. 25-THz O+S+C+L+U-Band Digital Coherent DWDM Transmission Using a Deployed Fibre-Optic Cable. In Proceedings of the European Conference on Optical Communication (ECOC), Glasgow, UK, 1–5 October 2023. [Google Scholar]
- Gu, J.; Cao, X.-Y.; Fu, Y.; He, Z.-W.; Yin, Z.-J.; Yin, H.-L.; Chen, Z.-B. Experimental measurement-device-independent type quantum key distribution with flawed and correlated sources. Sci. Bull.
**2022**, 67, 2167–2175. [Google Scholar] [CrossRef] [PubMed] - Grünenfelder, F.; Boaron, A.; Resta, G.; Perrenoud, M.; Rusca, D.; Barreiro, C.; Houlmann, R.; Sax, R.; Stasi, L.; El-Khoury, S.; et al. Fast single-photon detectors and real-time key distillation enable high secret-key-rate quantum key distribution systems. Nat. Photonics
**2023**, 17, 422–426. [Google Scholar] [CrossRef] [PubMed] - Li, W.; Zhang, L.; Tan, H.; Lu, Y.; Liao, S.; Huang, J.; Li, H.; Wang, Z.; Mao, H.; Yan, B.; et al. High-rate quantum key distribution exceeding 110 Mb s
^{−1}. Nat. Photonics**2023**, 17, 416–421. [Google Scholar] [CrossRef] - Zhou, L.; Lin, J.; Xie, Y.-M.; Lu, Y.-S.; Jing, Y.; Yin, H.-L.; Yuan, Z. Experimental Quantum Communication Overcomes the Rate-Loss Limit without Global Phase Tracking. Phys. Rev. Lett.
**2023**, 130, 250801. [Google Scholar] [CrossRef] [PubMed] - Deng, N.; Zong, L.; Jiang, H.; Duan, Y.; Zhang, K. Challenges and Enabling Technologies for Multi-Band WDM Optical Networks. J. Light. Technol.
**2022**, 40, 3385–3394. [Google Scholar] [CrossRef] - Okamoto, S.; Minoguchi, K.; Hamaoka, F.; Horikoshi, K.; Matsushita, A.; Nakamura, M.; Yamazaki, E.; Kisaka, Y. A Study on the Effect of Ultra-Wide Band WDM on Optical Transmission Systems. J. Light. Technol.
**2020**, 38, 1061–1070. [Google Scholar] [CrossRef] - Zhang, A.; Liu, Y.; Feng, L.; Lv, K.; Chen, H.; Du, Y.; Su, G.; Huo, X. Record 46.2Pbit·km/s real-time optical transmission over 1050-km G.652.D SSMF utilizing 400-Gbit/s transponder with a symbol rate of 91.6-GBaud. In Proceedings of the OptoElectronics and Communications Conference (OECC), Shanghai, China, 2–6 July 2023. [Google Scholar]

**Figure 1.**Simulation setup of the C6T and L5T transmission system. OTU

_{C/L}: optical transform unit, C/L: C and L wavelength combiner, OBA: optical booster amplifier, ONA: optical node amplifier, OPA: optical pre-amplifier, OPM: optical power monitor, WSS: wavelength selective switch.

**Figure 2.**Power spectrum at the receiver side after 5-span G.654.E fiber transmission with and without the APO scheme.

**Figure 3.**Performance comparison of the system with and without the APO algorithm in terms of the OSNR and Q-factor.

**Figure 9.**The OSNR performance versus frequency for the C band and L band after G.654.E fiber transmission.

Disclaimer/Publisher’s Note: The statements, opinions and data contained in all publications are solely those of the individual author(s) and contributor(s) and not of MDPI and/or the editor(s). MDPI and/or the editor(s) disclaim responsibility for any injury to people or property resulting from any ideas, methods, instructions or products referred to in the content. |

© 2024 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

## Share and Cite

**MDPI and ACS Style**

Zhang, A.; Liu, Y.; Feng, L.; Chen, H.; Du, Y.; Wu, J.; Lv, K.; Liu, H.; Sheng, X.; Huo, X.
Automatic Power Optimization of a 44 Tbit/s Real-Time Transmission System over 1900 km G.654.E Fiber and Widened C+L Erbium-Doped Fiber Amplifiers Utilizing 400 Gbit/s Transponders. *Photonics* **2024**, *11*, 88.
https://doi.org/10.3390/photonics11010088

**AMA Style**

Zhang A, Liu Y, Feng L, Chen H, Du Y, Wu J, Lv K, Liu H, Sheng X, Huo X.
Automatic Power Optimization of a 44 Tbit/s Real-Time Transmission System over 1900 km G.654.E Fiber and Widened C+L Erbium-Doped Fiber Amplifiers Utilizing 400 Gbit/s Transponders. *Photonics*. 2024; 11(1):88.
https://doi.org/10.3390/photonics11010088

**Chicago/Turabian Style**

Zhang, Anxu, Yuyang Liu, Lipeng Feng, Huan Chen, Yuting Du, Jun Wu, Kai Lv, Hao Liu, Xia Sheng, and Xiaoli Huo.
2024. "Automatic Power Optimization of a 44 Tbit/s Real-Time Transmission System over 1900 km G.654.E Fiber and Widened C+L Erbium-Doped Fiber Amplifiers Utilizing 400 Gbit/s Transponders" *Photonics* 11, no. 1: 88.
https://doi.org/10.3390/photonics11010088