TABLE OF CONTENTS The installation and powering up of an optical fiber communication system requires measurement techniques for verifying the link has been configured properly and that its constituent components are functioning correctly. Of particular importance are accurate and precise measurements of the optical fiber, since this component cannot be replaced readily once it has been installed. In addition, various test methods are needed for continually monitoring the link condition to verify that the performance requirements are being met during operation.
During the link design phase an engineer can find the operational parameters of many components on vendor data sheets. These include fixed parameters for fibers (e.g., core and cladding diameters, refractive index profile, mode-field diameter, cutoff wavelength); passive splitters, connectors, and couplers; and electrooptic components such as sources, photodetectors, and optical amplifiers. Once these parameters are known, there is no need to measure them again.
However, the attenuation and dispersion of a fiber can change during fiber cabling and cable installation. In single-mode fibers, chromatic and polarization mode dispersions are important factors that can limit the transmission distance or data rate. Chromatic dispersion effects are of particular importance in high-speed WDM links, and polarization mode dispersion ultimately can limit the highest achievable data rate in single-mode links. Measurement procedures for these parameters thus are of interest to the user, as are methods for locating breaks and faults in optical fiber cables.
When a link is being installed and tested, the operational parameters of interest include the bit error rate, timing jitter,...
