Submarine cables, as a key enabler of global connectivity, carry over 99% of the world's communication data traffic. With the continuous growth of international communication services and the vigorous development of the marine digital economy, the capacity for transoceanic communication is facing a severe challenge. Currently, with the maturation of capacity-expansion technologies such as higher-order modulation, Wavelength Division Multiplexing (WDM), and Polarization Division Multiplexing (PDM), the bottleneck problem of traditional fiber-optic transmission capacity is becoming increasingly evident. As a new generation of Space Division Multiplexing (SDM) fiber, 200 μm fine diameter fiber can meet the future Pbit capacity demand and reduce the per bit cost of submarine optical cable system.

The article focuses on the research and development of key technologies for thin-diameter optical fibers. By leveraging the inherent characteristics of optical fibers, a residual length model for thin-diameter fibers is established, and the boundary conditions for the residual length of thin-diameter fibers in submarine cables are solved. At the same time, the three factor and four level orthogonal experimental design is used to optimize the fusion parameters of fine diameter fiber, and the optimal fusion parameter combination of fine diameter fiber is obtained by defining the one-time qualification rate of fiber fusion.

Finally, the development of key technologies for the cabling of fine diameter fiber submarine cable is completed. The additional attenuation of fine diameter fiber cabling is less than 0.003 dB/km, which realizes the balance control between the additional attenuation of cabling and the reliability life. At the same time, the one-time qualification rate of fine diameter fiber fusion is controlled to be more than 90%, meeting the requirements of ultra long-distance transoceanic communication. The developed submarine cable has passed the key performance test of submarine cable recom-mended by International Telecommunication Union-Telecommunication Standardization Sector (ITU-T) G.976 and the 5 km deep sea trial test, and the change of light transmission performance is far less than 0.05 dB.

The performance indicators of the high fiber count and low additional attenuation fine diameter fiber submarine cable developed in this paper meet the technical requirements of submarine cable communication systems, providing important technical support for the development of the next generation of fine diameter fiber submarine communication systems.