Field Experience with Fiber-Optic Cable Installation, Splicing, Reliability, and Maintenance
The experience obtained during the installation of more than 700 sheath km of fiber-optic cable is summarized. These include in-building, underground (duct), aerial, buried, and underwater installations. In general, no special precautions are required except to maintain the specified pull tension and cable bend radius. Field splicing is discussed and results are given on splice losses with and without splice loss monitoring with the optical time domain reflectometer. A 28 percent learning curve for fusion splicing is derived. Reliability data on 312 sheath km of installed cable and field splices are presented. Most of the cable failures were in the "uncontrollable extrinsic category," and most of these were due to complete cable cuts. Finally, restoration is reviewed with emphasis on troubleshooting, repair, emergency restoration, and offset breaks.
Protection of Optical Fiber Arc Fusion Splices
Protection of arc fusion splices is considered with respect to low temperature excess loss and reliability against fiber breakage. The most important factor leading to increased loss at low temperatures seems to be nonuniform radial stress on the fiber. To obtain an efficient protection against effects of external forces and thermal stress, a soft silicone buffer should be used together with an outer sleeve of steel. The optimum design of splice protectors is based on detailed stress calculations supplied with experimental data.
Continuous calibration of a vacuum ultraviolet system from 65 to 125 nm by a cascade arc and comparison with the calibrated line radiation of a hollow cathode.
A high-power stationary helium cascade arc has been developed as a standard source for continuum radiation in the VUV spectral range from 65 to 125 nm. The calibration of the VUV system response was based on the calculated and measured continuum radiation of a 2-mmphi pure He arc. Diagnostics of the arc plasma in partial thermal equilibrium yielded the electron density and the temperature that were inserted in the calculations of the continuous radiation. The results were compared with the helium, argon, and krypton radiation lines of a high-current hollow cathode lamp. This lamp was built according to the construction drawings of a hollow cathode, which was calibrated by means of the electron synchrotron radiation at the Physikalisch Technische Bundesanstalt Berlin.