The optical fiber cable measurement instruments developed by NTF for field use in the 1.3 μm wavelength are discussed. The properties of a stabilized optical light source for single-mode fiber attenuation measurement, optical time-domain reflectometer using a Q-switched Nd:YAG laser as a light source, and chromatic dispersion measurement instrument are described. From the measurement results, these instruments are revealed to be suitable in constructing and maintaining singlemode fiber optical transmission lines.

On designing optical fiber cable, it is necessary to deal with optical fiber weakness, such as small breaking elongation compared to metal materials and excess loss under both lateral and hydraulic pressure. This paper presents a structural design method for the submarine optical fiber unit and cable based on the study of both lateral and hydraulic pressure characteristics. This paper also clarifies that the fiber proof test level has been determined for new cables to be applied in sea areas 8000 m in depth.