Submarine cable performance requirements

Submarine optical cables require long-distance, low-attenuation transmission, and must adapt to the seabed environment. The requirements for water pressure resistance, air loss resistance, tensile resistance, and impact resistance are particularly strict. Optical fibers have higher requirements; low loss, high strength, long manufacturing length, and ability to withstand strong pressure and tension are required. The structure of the deep-sea optical cable is relatively complicated: the optical fiber is set in a U-shaped groove plastic skeleton, and the groove is filled with ointment or elastic plastic body to form a fiber core. The fiber core is wrapped with high-strength steel wire. During the wrapping process, all the gaps should be filled with waterproof materials, and then a layer of copper tape is wrapped around the steel wire and welded to make the steel wire and copper tube form an anti-corrosion Combination of compression and tension. A layer of polyethylene sheath is added on the outside of the steel wire and copper pipe. Such a tight multi-layer structure is to protect the optical fiber, prevent breakage and prevent the intrusion of seawater. In shark-infested areas, a polyethylene sheath is added to the cable.

Submarine cable

Structural Analysis of Typical Submarine Optical Cable

1. Polyethylene layer

Special requirements for submarine cables

Whether it is the design of land optical cable or submarine optical cable, it is to ensure that the optical fiber can work in a relatively stable and safe environment, and can transmit optical signals for a long time and stably without external interference. Different environments have different requirements for the production of optical cables. The design of the submarine optical cable must ensure that the optical fiber is not affected by external forces and the environment. The basic requirements are: it can adapt to the submarine pressure, wear, corrosion, biological and other environments; it has a suitable armor layer to prevent the damage of fishing trawls, anchors and sharks; the cable breaks When it is time to reduce the length of seawater infiltrating into the cable; it can prevent the hydrogen from infiltrating into the cable from the outside and prevent the hydrogen generated inside; it has a low-resistance remote power supply circuit; it can withstand the tension during laying and recovery; the service life is average Over 25 years is required.

Performance requirements and production process optimization of optical fibers in submarine optical cables

Submarine optical cables require long-distance and low-attenuation transmission, and must adapt to the seabed environment. The requirements for water pressure resistance, air loss resistance, tensile resistance, and impact resistance are particularly strict. The transmission capacity of optical fiber is large, and the distance between relay stations is long, which is suitable for long-distance communication on the seabed. In order to meet these specific requirements, the basic structure of the submarine optical cable is to spirally wrap the optical fiber after one or two coatings in the center, around the strengthening member (made of steel wire), and place it in a special stainless steel tube. Among them, the steel wire with high-strength arch structure is wound around the tube, and the steel wire layer is wrapped with copper tube, so that the micro/macro bending does not occur when the optical cable is laid. Finally the outer sheath is extruded. Although the manufacturing process of the submarine cable avoids the micro/macro bending loss of the optical fiber caused by the laying process of the submarine cable, the inhomogeneity in the production process of the submarine cable makes the longitudinal extrusion of the metal or ointment on the optical fiber uneven, resulting in The external stress on the optical fiber is not uniform, so as to minimize the attenuation of the optical fiber and achieve longer distance transmission. Optical fibers used in submarine optical cables have higher requirements than optical fibers used in terrestrial optical cables; low loss, high strength, long manufacturing length, and ability to withstand strong pressure and tension are required.