A Flat Long-Reach of WDM-PON and Optical Switching for Future National Data Center Interconnects: A Review

Section: Review Article
Issue
Vol. 35 No. 4 (2026): Volume 35, Issue 4
Pages
67-84

Abstract

The national fiber backbone requires continuous upgrading due to the increasing demand for data transfers between datacenters and end users, resulting in congestion and delays. This paper presents a structured review of national-scale flat Long-Reach Wavelength Division Multiplexing Passive Optical Network (LR WDM-PON) architectures. These architectures are integrated with optical switching technologies for distributed Data Center Interconnects (DCI) to enhance the performance of optical networks. The study analyzes the evolution of WDM-PON toward extended-reach operations and highlights the role of Optical Add-Drop Multiplexers (OADMs) in wavelength-level routing. Additionally, we discuss key challenges that limit optical transmission, such as chromatic dispersion accumulation, nonlinearities, and Optical Signal-to-Noise Ratio (OSNR) degradation caused by cascaded amplification. Special attention is given to dispersion compensation strategies, such as the deployment of dispersion-compensating fiber (DCF), and their impact on Bit Error Rate (BER) performance in extended-reach scenarios. This review synthesizes recent experimental and theoretical studies to explain the primary design frameworks and physical constraints involved in scaling transparent optical networks to a national level.

Keywords:

Optical Switching, Long-Reach WDM-PON, Data Center Interconnects (DCI), National Fiber Backbone, Transmission Impairments

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Authors

Farhad Salih Ahmed

Department of Computer Science, College of Computer Science and Information Technology, University of Kirkuk, Kirkuk, Iraq

Essa Ibrahim Essa

Department of Computer Science, College of Computer Science and Information Technology, University of Kirkuk, Kirkuk, Iraq

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DOI: 10.33899/jes.v35i4.62043

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“A Flat Long-Reach of WDM-PON and Optical Switching for Future National Data Center Interconnects: A Review”, JES, vol. 35, no. 4, pp. 67–84, Oct. 2026, doi: 10.33899/jes.v35i4.62043.
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[1]
“A Flat Long-Reach of WDM-PON and Optical Switching for Future National Data Center Interconnects: A Review”, JES, vol. 35, no. 4, pp. 67–84, Oct. 2026, doi: 10.33899/jes.v35i4.62043.