Design and performance of nonmetallic waterproof optical fibercable using water-absorbent polymer

A nonmetallic optical fiber cable waterproofed with absorbent polymer was developed. Methods are proposed for evaluating the reliability of absorbent polymer in order to apply it as a waterproofing material, and a type of polyacrylic acid is selected. In addition, a waterproofing design is established based on a theoretical estimate of the water penetration length in the cable space. Among other findings, it was shown that the optical fiber loss of water-penetrated cable increases due to freezing. The allowable penetration length of waterproof cables can be determined so as to suppress this loss increase. Cables manufactured using this new design and absorbent polymer showed performance sufficient for practical application