Fiber characterization is used to determine a network’s capacity to handle applications. It provides a snapshot of the entire link, including all interconnection points, splices and fiber sections. Fiber characterization confirms that a fiber is fit to carry traffic by validating insertion loss, optical return loss, chromatic and polarization mode dispersions, and serves as a reference for subsequent commissioning and troubleshooting.
In lab and network equipment manufacturing environments, R&D and Carrier engineers use scalable testing solutions with port density, multi-user accessibility and automation capability to cover a wide range of technologies, including next-generation SONET, SDH, OTN and Fibre Channel.
In the field, technicians must properly inspect fiber-optic cables to identify defects and scratches (against IEC/IPC standards or user-defined criteria), and determine their impact on connector performance (accurate pass/fail verdicts). This inspection requires special tools, namely a scanning wheel, fiber-inspection probe and cleaning kit.
For all fiber types and all wavelengths, insertion loss is monitored as a function of the bending angle. Although angles differ, the behavior remains the same. Fixed-angle bending generates excessive loss, and in some cases, leads to flawed identification.
ORL, which is caused by the reflective nature of network components including the fiber, mechanical connections and poor-quality splices, is a key parameter because it can affect transmitter performance and service quality. It can be measured using a backreflection tester, or an OLTS with a backreflection option.
OTDRs are used to perform complete link characterization because they measure the loss, reflectance and attenuation of all connections, splices and splitters in a network. They also locate (distance) them.
Chromatic dispersion (CD) and polarization mode dispersion (PMD) are speed-limiting phenomena that hamper transmission in high-speed networks, starting at 10 Gbit/s. They threaten the integrity of a signal and affect the quality of service.
Attenuation is power loss that results from a variety of scattering and absorption phenomena. The objective is to measure the transmitted intensity of a spectral pulse of light at a number of wavelengths in order to calculate the attenuation rate.