11 – Submarine fibers

Optical fibers provide the backbone of telecommunication systems, particularly undersea networks where low loss and large effective area are essential for enabling data transmission over thousands of kilometers. In this chapter, we present an overview of optical fibers used for undersea communications. These fibers include the non-zero-dispersion-shifted fibers (NZ-DSFs) and the negative dispersion slope fibers used in dispersion-managed systems and the ultra-low-loss fibers which are now being deployed in coherent systems. We briefly discuss the design approach and manufacturing process, as well as the origins and importance of key fiber properties such as attenuation, dispersion and effective area. The interplay between these fiber parameters will be illustrated in examples of effective area management, dispersion compensation, and dispersion-managed fibers.