Radiation Tolerant Optical Fibers: From Sample Testing to Large Series Production

The process of selecting, manufacturing, and installing a large quantity (2500 km) of commercially available radiation tolerant specialty fibers is described. Radiation tests of various types of fibers from different manufacturers provided sufficient understanding of the radiation effects to select the best performing fiber type. Systematic verification of a sample of each preform assured a constant quality of the series production and allowed assessing the impact of small variations in the manufacturing process on the radiation hardness and the optical transmission characteristics. The fiber cable installation technique based on microjetting and plastic cable ducts has been validated for areas with high levels of radiation.

I. Introduction

Silica (SiO₂) glass is well suited for guided optical transmissions because of the low attenuation of light. Indeed, many present day optical fibers are made of silica and are essentially long strands of SiO₂ composed of a central core surrounded by a cladding.