In 1993, AT & T first discovered the phenomenon of four-wave mixing caused by the nonlinear effect of optical fiber. Four-wave mixing can realize wavelength conversion, that is, retransmitting information carried by a wavelength channel to other wavelength channels causes crosstalk between the information transmitted by each wavelength channel of the dense wavelength division multiplexing system. Since the effective core area of the G.653 fiber is smaller than that of the G.652 fiber, and the dispersion coefficient of the G.653 fiber at 1550 nm is zero, the four-wave mixing efficiency of the G.653 fiber is high , The interference is very serious. In order to overcome the problem that the dispersion of G.652 fiber at 1550nm wavelength is large, and the four-wave mixing of G.653 fiber is serious, in 1994, the optical fiber researchers of Lucent and Corning of the United States determined to develop a new fiber The optical fiber itself solves the problems that the dispersion of the G.652 optical fiber at 1550nm operating wavelength is too large and the four-wave mixing of the G.653 optical fiber at 1550nm operating wavelength is serious. Based on the dispersion-shifted single-mode fiber, the optical fiber researchers developed a fiber with a small positive dispersion or a negative dispersion at the operating wavelength of 1550nm by changing the refractive index distribution structure of the fiber. It is called a non-zero dispersion-shifted single-mode fiber. The characteristic of this single-mode optical fiber is that the dispersion in the working window of 1530 ～ 1565nm is not zero, and a proper dispersion system value that can suppress four-wave mixing is maintained. ITU-T named non-zero dispersion shifted single-mode fiber as G.655 fiber. Because the dispersion coefficient of this optical fiber in the working window of 1530 ～ 1565nm is small and not zero, it is necessary to use a small amount of dispersion compensation fiber when using G.655 fiber to form a line for a long distance above 10Gbit / s. Optical fiber is currently the preferred optical fiber type for dense wavelength division multiplexing optical fiber communication systems that achieve long-distance, high-capacity communication above 10 Gbit / s.
The G.655 proposal is the first version V1.0 (1996) created in 1996. It was revised twice in 2000 and 2003 to form the third version V3.0 (03/2003). In this version, G.655 The basic types of optical fiber are subdivided into three categories: G.655A, G.655B, and G.655C. The upper limit of the L-band is determined to be 1625nm, and the PMD limit of G.655C fiber is 0.2ps /. The fiber winding radius for the microbend attenuation test was reduced to 30mm. Two types of optical fibers, D and E, have been added to the latest version (03/2006).
What is the difference between G655 fiber and G652, G653, G654 fiber
For WDM systems: G.655 transmission performance is stronger than G.652. Not only the attenuation is small, but the dispersion compensation is also small; the transmission distance is far.
For SDH systems: Generally, 652 fiber is used for less than 40km, and 655 fiber is needed for distances greater than 40km!
G.652 fiber: (dispersion-unshifted fiber)
The most widely used optical fiber has two windows of 1310nm and 1550nm, the dispersion at 1310nm is small but the attenuation is large, and the attenuation at 1550nm is small but the dispersion is large
G.653 fiber (1550 best performance fiber):
It is suitable for TDM systems, but it is not suitable for WDM systems due to the internal four-wave mixing effect.
The dispersion-shifted fiber shifts the zero-dispersion point from 1310nm to 1550nm by changing the waveguide structure, so that the dispersion and attenuation of the 1550nm window are very low.
The biggest weakness of G.653 fiber is the existence of four-wave mixing effect
G.654 fiber: (1550 minimum attenuation fiber)
The focus is on reducing the attenuation of 1550, mainly used for submarine fiber optic communication
G.655 fiber: (improved version of G.653 fiber)
Shifting the zero dispersion point to around 1550 instead of shifting to 1550 like G.653 eliminates four-wave mixing and is suitable for WDM systems.