Submarine optical cables are extremely vulnerable to seawater corrosion due to long-term immersion in high-concentration seawater. In addition, hydrogen molecules will diffuse into the glass material of the fiber, making the loss of the fiber larger. Therefore, the submarine optical cable should not only prevent hydrogen from being generated inside, but also prevent hydrogen from penetrating into the optical cable from the outside. At present, the structure of the submarine optical cable is to helically wrap the optical fiber after one or two coatings in the center, and the strengthening member (made of steel wire) is wrapped around it.
The submarine optical cable looks a bit like an oil pipeline. In fact, the biggest difference between a submarine optical cable and a terrestrial optical cable is its "armour protection". In general, "armor protection" includes
The reason why so many layers of protection are required is because the submarine environment faced by submarine optical cables is extremely complex and harsh. The first is the corrosion of seawater. The outer polymer layer of the submarine optical cable is to prevent the reaction of seawater and the reinforced steel cable to produce hydrogen. Even if the outer layer is really corroded, the inner copper pipe, paraffin, and carbonic acid resin will prevent hydrogen from harming the optical fiber. The infiltration of hydrogen molecules will lead to an increase in the attenuation of optical fiber transmission.
In addition to seawater corrosion, submarine optical cables are also subject to submarine pressure, natural disasters (earthquakes, tsunamis, etc.), and human factors (fishermen's salvage operations). Without enhanced armor protection, submarine optical cables cannot work stably for a long time.
Sharks attack submarine cables
However, even with such strict protection, the submarine optical cable still cannot be used permanently, and its service life is generally only 25 years.
