<title>Optical Fiber Composition And Radiation Hardness</title>

Germanium phosphosilicate and germanium borosilicate,fibers doped with cerium were fabricated and tested for their responses to steady-state Co60 radiation at -55°C, +20°C and +125°C. A fiber with germanium, boron and phosphorous in the silicate core and doped with antimony in the core and clad was similarly tested. All of the fibers showed significant improvements in radiation hardness at 20°C compared to undoped fibers of the same base composition. At -55°C, however, all except the cerium doped germanium phosphosilicate were very radiation sensitive and also showed increases in the rate of induced loss at +125°C. The cerium doped germanium phosphosilicate fiber showed virtually no change in radiation sensitivity at the temperature extremes and could prove useful in applications requiring relatively short lengths of fiber.