The application of optical fiber networks is more and more extensive, but it should be noted that in the face of different application requirements, the optical fibers used have strict differences. The practical application of optical fibers in various optical networks determines the requirements for the performance of optical fiber technologies. Different fiber networks use fiber optics with different application technologies.
The application of fiber optic technology in transmission systems is first achieved through various optical networks. Up to now, the topology of various optical fiber transmission networks built can basically be divided into three categories: star, bus and ring. Further from the layered modeling of the network, the network can be divided into several layers from top to bottom, and each layer can be divided into several sub-networks. In other words, the network and network formed by each switching center and its transmission system can also be further divided into several smaller sub-networks, so that the entire digital network can effectively communicate services, and the all-digital integrated service digital network ( ISDN) is the overall goal of the communications network. The popularization of ADSL and CATV and the continuous increase of the capacity of metropolitan area access systems, and the expansion of the backbone backbone network all require different types of optical fibers to take on the responsibility of transmission.
Dispersion Compensation Fiber (DCF)
Fiber dispersion can broaden the pulse and cause bit errors. This is a problem that must be avoided in the communication network and a problem that needs to be solved in long-distance transmission systems. In general, fiber dispersion includes material dispersion and dispersion of the waveguide structure. Material dispersion depends on the dispersibility of the silica masterbatch and dopant used to make the fiber, and waveguide dispersion is usually a mode of effective refractive index with wavelength. And the tendency to change. Dispersion-compensating fiber is a technology used to solve dispersion management in transmission systems.
In the quartz fiber core doped with rare earth elements can be made into amplifying fiber, such as Erbium-doped amplifier fiber (EDF), Erbium-doped amplifier fiber (TOF) and so on. The amplifying optical fiber and the traditional quartz optical fiber have good integration performance, and also have many advantages such as high output, wide bandwidth, low noise and the like. Optical fiber amplifiers (such as EDFAs) made with amplifying fibers are the most widely used critical devices in today's transmission systems. The amplification bandwidth of the EDF has been extended from the C-band (1530 1560 nm) to the L-band (1570 1610) with an amplification bandwidth of 80 nm. The latest research results show that EDF can also perform optical amplification in the S-band (1460 1530), and an inductive Raman fiber amplifier has been manufactured and amplified in the S-band.
Supercontinuum (SC) Occurrence Fiber
Supercontinuum is the phenomenon of spectral ultra-wideband when a strong light pulse is transmitted in a transparent medium. As a new generation of multi-carrier light sources has attracted widespread attention in the industry. Since the occurrence of ultra-wideband light observed by Alfano and Shapiro in large-capacity glass in 1970, ultra-wideband light has been observed in various materials such as optical fibers, semiconductor materials, and water.
Optical device optical fiber
With the construction and expansion of a large number of optical communication networks, the use of active and passive devices continues to increase. Among them, optical fiber type devices are most widely used, mainly including optical fiber amplifiers, optical fiber couplers, optical splitters, fiber gratings (FG), and AWG. The above-mentioned optical device must have low loss, high reliability, and easy to use the low loss coupling and connection with the communication optical fiber to be applied to the communication network. This led to the development and production of fiber optics for FG and device coupling (optical fiber for LP).
PM fiber was originally developed as a coherent light transmission fiber. Since then, it is used in fiber optic gyro and other optical fiber sensor technology fields. In recent years, due to the increase in the number of wavelength division multiplexing in the DWDM transmission system and the development of high speed, polarization maintaining fibers have been more widely used. Currently the most widely used is Panda Optical Fiber (PANDA).