>>Proposed new requirements for the development of fiber optic network
Next Generation Network has led to many of the views and arguments. Some experts predicted that, regardless of how the next generation network development, must be to reach the three worlds, that the light of the world and access level in the IP world, send level, on the level of service on the wireless world. The next-generation transport network requires higher rates, greater capacity, none other than the non fiber optic network, but the development of high-speed backbone transmission optical fiber requirements.
a. Expand the transmission capacity of a single wavelength
Currently, the transmission capacity of a single wavelength up to 40Gbit/s, and has started execution of 160Gbit/s. 40Gbit/s over the transmission fiber PMD will make certain requirements the 2002 the ITU-TSG 15 of meeting, the United States has put forward a proposal to introduce a new type of fiber (G.655.C) 40Gbit/s system, and recommended explore its the PMD transmit some doubt perform in-depth, perhaps in the near future there will be a dedicated 40Gbit/s optical fiber type.
b. To realize long distance transmission
Free relay transmission is ideal backbone transmission network, some companies have been able to dispersion Sarkozy management skills, 2000-5000km radio relay transmission. Some companies is to further improve the fiber indicators, using skills Raman optical amplification, can prolong the optical transmission distance.
c. Adapt to the use of DWDM skills
Currently the 32×2.5Gbit/s DWDM system already use 64×2.5Gbit/s and 32x10Gbit/s system has been developed and made good progress. Etensive use of DWDM systems, fiber nonlinear index put forward higher requirements. ITU-T standard fiber nonlinear properties and testing essentials (G.650.2) recently completed the fiber nonlinearity test indicators clear, the effective area of the fiber will propose indicators, especially for the nonlinear characteristics of G.655 fiber requirements for further improvement.
>> The fiber standard subdivision promote accurate use of fiber
In 2000, the World Telecommunications Standards Assembly approved the original G.652 fiber re-divided into G.655.A, G.652.8 and G.652.C3 class of fiber optic; G.655 fiber re-to divided into G.655.A and G.655.B two types of optical fiber. Subdivision of this fiber standard for accurate use of the optical fiber, and the standard refinement also improves the fiber index requirements (such as some fiber geometry parameters Tolerance smaller), clear the different levels of the network and different indicators of the use of fiber optic transmission system requirements (such as the provisions of the PMD value), and some of the new concept of indicators (such as the vertical dispersion uniformity “, etc.), and a good role in the rational use of fiber. All these proposed changes, the emergence of sub-recommendations and the drafting of the proposed new child, means that the optical fiber classification and indicators, some improved testing essentials or major upgrade; marks required fiber quality improvement or use direction the adjustment is worthy the new trends Fibre skills carefully.
>> New fiber in constantly appeared
Fiber skills in order to meet the market need, indicators improved in the emerging new types of optical fiber, while the major companies are stepping up the development of new varieties.
a. New high-capacity long-haul fiber for long-distance communication
Mainly the large effective area, the new G.655 fiber, low dispersion maintain low PMD values that can make the capacity of the existing transmission system to easily upgrade to 10 ~ 40Gbit / s, and easy to pull on the fiber using distributedZeeman amplification, greatly extend the transmission distance of the optical signal.
b. New Low water peak fiber used in MAN communication
The MAN design need to consider also need to consider the possibility of use by CWDM equipment to simplify and reduce costs. the low water peak optical fiber bandwith is greatly expanded, so that in the extension band of 1360-1460nm CWDM system is greatly optimized, the transmission channel is increased, an increase of the transmission distance. Also requires some MAN design may require not only the water peak fiber optical fiber with negative dispersion value of light source devices, on the one hand, can be offset by positive dispersion, on the other hand can be combined using this negative dispersion fiber with G.652 fiber G.655 standard fiber, the use of it for dispersion compensation, thus preventing the complex dispersion compensation design, and cost savings. If in the future in the metro fiber Raman amplification skills, this network will have a distinct advantage. But, after all, MAN specification is not very mature, metro fiber specifications will be changing with the changes in the patterns of MAN.
c. New multimode fiber for LAN
Due to the development of high-speed LAN and CPN, integrated wiring system uses a multimode fiber cable instead of digital cable, multimode fiber market share will gradually increase. Was selected multimode fiber, multimode fiber LAN transmission distance is shorter, 50% to 100% more expensive than the price of single-mode fiber, but its optical devices supporting the choice of a light-emitting diode, the price is much cheaper than the laser tube , and the multimode fiber have a larger core diameter and numerical aperture, easy to connect with the coupling, the corresponding connector, couplers and other components price is also much lower. ITU-T has yet to accept 62.5/125μm multimode fiber standard, but due to the need of LAN development, it still has been widely used. Elected by the ITU-T G.651 50/125μm fiber, i.e. in the standard type multi-mode fiber, its core diameter is small, the coupling and connection of the corresponding difficult, although some use in some European countries and Japan, but in North America and most countries in Europe rarely used. These questions, some companies have implemented improved fiber optic developed a new 5O/125μm of fiber-optic gradient type (G1), different from the traditional 50/125μm fiber core gradient refractive index distribution, it will be the bandwidth of normal distribution executed adjusted to cope with the use of 850nm and 1300nm two windows, this improvement may 50/125pm optical fiber use in local area networks to find new markets.