How to relay submarine fiber optic cables?
Based on these definitions, a relay free submarine fiber optic cable is developedThe span of the system can reach about 400 kilometers, and the transmission distance of the relay system can reach thousands of kilometers.The addition of an optical amplifier will lead to more restrictions on the relay submarine fiber optic cable system. One problem is: the cable itself must provide electrical power from the junction of the shore, but the power transmission capacity of cable is limited, which limits the total number of amplifiers, which also limits the number of fiber optic cable.
Submarine optical cable without relay and relay submarine fiber optic cable. Here, repeaters are electronic devices at the bottom of the sea, not electronic optical repeaters used in previous undersea cables (working at 1300nm wavelengths). The current submarine optical cable system works at the 1500nm window using an optical amplifier. However, if the fiber amplifier is sufficient to obtain electrical power at the end of the fiber optic cable, then such a system should also be considered a relay. Repeaters can also refer to a cylindrical containing light amplifier and pump source for light sealed containers, but if the pump source of optical amplifier is located on the shore of the laser diode, optical amplifier that is installed on the seabed is not a repeater. Based on these definitions, a relay free submarine fiber optic cable is developed
At present, the number of fiber pairs in each submarine cable is limited to 4 or 8. In addition, the housing standard repeater can accommodate 8 fiber amplifiers, but the 4 is enough for optical fiber, and the shell model can accommodate the repeater optical amplifier this is more than 8 times, is suitable for occasions of fiber. Amplifiers with relay submarine cables are typically about 50 kilometers apart, about half the length of the land long haul fiber optic cable system. This is necessary because the length of the submarine optical cable system is often thousands of kilometers, much longer than that of terrestrial optical fiber cables. In submarine optical fiber cables, the gain of optical amplifiers should be kept at a low level, usually only about 10dB, which is to control the spontaneous emission noise and nonlinear effects of amplification, and these effects are accumulated along the length of optical fiber cables. The input power of high and low gain power is helpful to balance the entire spectrum of the optical amplifier, this point is very important, because after the 100 amplifier, small gain difference will accumulate a huge problem. The Raman amplifier in the last section of the optical fiber can not only amplify the signal of the optical amplifier, but also realize the gain equalization in the whole WDM spectrum. The current submarine optical fiber cable system uses only C band erbium doped fiber amplifier, but because of the increase of single channel rate and multiplexing wavelength, the capacity of submarine WDM system has been greatly improved. Early WDM submarine fiber optic system, each fiber transmission 4 2.5Gbit/s channels, such as 4 pairs of optical fiber, the total capacity
