Optical amplifier refers to a new type of all-optical amplifier used in optical fiber communication lines to achieve signal amplification. According to its position and function in the optical fiber line, it is generally divided into three types: relay amplification, pre-amplification and power amplification. Compared with the traditional semiconductor laser amplifier (SOA), OFA does not need to go through complex processes such as photoelectric conversion, electro-optical conversion and signal regeneration, and can directly amplify the signal all-optically. Relay amplification for optical communication. It can be said that OFA has laid a technical foundation for the realization of all-optical communication.
Semiconductor Optical Amplifiers (SOAs) and OFAs. Semiconductor optical amplifiers utilize the inherent stimulated radiation amplification mechanism of semiconductor materials to achieve optical amplification, and their principles and structures are similar to semiconductor lasers. The optical amplifier is different from the semiconductor amplifier. The active medium of the optical amplifier is a special fiber or transmission fiber, which is connected to the pump laser; when the signal light passes through this fiber, the signal light is amplified. Optical amplifiers can be divided into rare earth ion optical amplifiers and nonlinear optical amplifiers. Like semiconductor amplifiers, the working principle of rare-earth-doped ion optical amplifiers is also stimulated radiation; while nonlinear optical amplifiers use the nonlinear effect of optical fibers to amplify optical signals. Practical optical amplifiers include Erbium-Doped Optical Amplifier (EDFA) and Raman Optical Amplifier.
Optical fiber amplifiers can not only directly amplify optical signals, but also have real-time, high-gain, broadband, online, low-noise, low-loss all-optical amplification functions, and are essential key components in the new generation of optical fiber communication systems; This technology not only solves the limitation of attenuation on the transmission rate and distance of optical networks, but more importantly, it creates wavelength division multiplexing of frequency bands, which will enable ultra-high-speed, ultra-large capacity, ultra-long-distance wavelength-division multiplexing, dense wave The realization of division multiplexing, all-optical transmission, and optical soliton transmission is an epoch-making milestone in the development history of optical fiber communication. At present, the practical optical amplifiers mainly include erbium-doped optical amplifiers, semiconductor optical amplifiers and fiber Raman amplifiers. Among them, erbium-doped optical amplifiers have been widely used in long-distance, large-capacity and high-speed optical fibers due to their superior performance. Communication systems, access networks, optical fiber CATV networks, military systems and other fields, as power amplifiers, relay amplifiers and preamplifiers.
At present, optical amplifiers mainly include erbium-doped optical amplifiers, semiconductor optical amplifiers and fiber Raman amplifiers. According to their application in optical fiber networks, optical amplifiers have three different uses: they are used as power amplifiers on the transmitter side to improve the emission It is used as an optical pre-amplifier before the receiver to greatly improve the sensitivity of the optical receiver; it is used as a repeater amplifier in the optical fiber transmission line to compensate for the optical fiber transmission loss and extend the transmission distance.