Fiber characterization and troubleshooting for submarine networks

High-speed connectivity that protects the current network infrastructure requires broad expertise and a wide-range of tests to qualify the state of the fiber, perform fiber characterization and assess the integrity of data transmission over long-haul and ultra-long-haul networks—as is the case with cable testing in submarine networks. And, when it comes to high-speed, transoceanic transmission, assessing fiber quality is a must.

Description

Expertise for every transmission stage

EXFO's 40G/100G submarine network expertise encompasses network components and fiber testing throughout all the transmission network stages. Once the basic parameters (i.e., insertion loss (IL), optical return loss (ORL), etc.) are confirmed, the next step is to qualify the fiber to ensure that it is fit to transport actual traffic. This is when polarization-mode dispersion (PMD) and chromatic dispersion (CD) testing are required. CD causes light pulses to broaden when traveling within the fiber, up to a point where the bit error rate increases. While CD can be compensated over a wide wavelength range, it is costly to do so. Therefore, knowing where the issue lies is key. In addition, for submarine cable testing, PMD is also critical. Due to changes in the fibers’ refraction index and physical stresses on the cable, the two polarization states of light travel at slightly different speeds. This spreads the pulse over time and distance, eventually increasing bit error rate, making CD and PMD testing critical.

Total link characterization is an important step that provides a snapshot of the entire link, including all interconnection points, fusion splices and fiber sections. Link characterization also serves as a future reference when performing commissioning and troubleshooting on the same link. Naturally, with submarine cables, distance is always an issue—for coastal networks of up to 250 km, the solution is an OTDR with a dynamic range of up to 50 dB that can test over distances of up to 250 km.

Finally, the critical weakness of undersea cables is their vulnerability to damages caused by fishing and vessel anchoring. How can you keep a constant and vigilant eye on these optical fiber cables? With a stand-alone OTDR test solution. Providing a measurement range of up to 200 km, these easy-to-manage units will cost-effectively monitor coastal route topologies (festoon style). They will also keep you up-to-date on the status of the fibers and cables, and alert you and your systems—through various messaging channels—when your most valuable asset is potentially impaired.