How does the submarine cable work?

Many people are full of curiosity about submarine cables. Submarine cables are actually a kind of long-distance optical fiber. Generally, long-distance optical cables in the world use submarine cables. So how do submarine cables be laid?
Compared with submarine cables, the laying of terrestrial cables is much simpler. You only need to dig the cable trench and bury the cables in it. Submarine cables are not that simple. To lay the submarine cables, you must first have a ship. The submarine optical cable laying ship puts the submarine cable on the ship, and then the ship slowly sinks the cable into the seabed according to the prescribed route. It sounds not difficult, but the actual operation is actually very difficult. At present, the international long-distance submarine cable laying is almost unfavorable. Developed countries such as Japan and Europe have a monopoly. However, the domestic cable industry has developed rapidly in recent years. Leading companies such as Huawei have the technology and ability to lay long-distance submarine cables.

The laying of submarine optical cables is usually done by a cable laying machine that digs the seabed. The working principle is a bit like the plow used in plowing the field. During operation, the rows of water jet holes at the bottom of the cable burial machine simultaneously spray high-pressure water jets to the seabed to flush out the seabed sediment to form an optical cable trench. At the same time, the fairlead on the upper part of the equipment can guide the optical cable to the bottom of the optical cable trench. The cable laying machine is towed forward by the submarine optical cable laying vessel, and transmits various instructions through the working optical cable through the laying vessel.
In order to avoid damage to the optical cable due to too small bending radius or excessive tension, the laying of the optical cable-laying ship must use underwater monitors and underwater remote control vehicles to continuously monitor and adjust to control the sailing speed of the laying ship and the release speed of the optical cable. Control the angle of entry of the optical cable into the water and the laying tension and avoid uneven places and reefs. Of course, after the fiber optic cable is laid, there will be landfill work. In the past, sea currents were used to allow sand to naturally cover the trenches to save time for burying cables, but it was also vulnerable to sea currents and other unstable factors (such as sharks). Therefore, it is now common to use an underwater robot equipped with a high-pressure water pump to flush a ditch and then put it in and bury the soil.