Submarine Optical Network Testing
WhitepaperJanuary 22, 2026
Submarine optical cables form the backbone of global communications, carrying the majority of the world’s rapidly expanding internet traffic driven by cloud computing, IoT, and AI services.
As cable systems grow in scale and complexity, accurate testing and fault identification become essential to ensure reliability. This paper provides an overview of submarine cable architecture, the need for precise diagnostics, and the role of Coherent Optical Time Domain Reflectometry (C‑OTDR) in long-distance fault location. By leveraging coherent detection and submarine repeater return paths, C‑OTDR enables highly sensitive measurements at practical DWDM wavelengths, even across ultra‑long spans exceeding 20,000 km. The paper concludes by highlighting the effectiveness of advanced C‑OTDR solutions—such as Anritsu’s MW90010B—in enabling rapid, accurate fault detection and full characterization of submarine fiber infrastructure.
