Fiber-optic cable and communication cable technology development and Thinking

1 characterized by the development of optical fiber technology
1.1 The development of fiber-optic networks, new requirements
Next Generation Network (NGN) caused a lot of views and controversies. Some experts predicted that, regardless of how the development of next generation networks, we will have to reach the three worlds, that is, at the level of IP services world, the light transmission level of the world and the access level of the wireless world. Next-generation transport network demands for higher speed, greater capacity, fiber-optic network, which is not a go, but the development of high-speed backbone transmission fiber also put new demands.
(1) expand the transmission capacity of a single wavelength
At present, the single-wavelength transmission capacity has reached 40 Gbit / s, and has started to carry out 160 Gbit / s research. 40Gbit / s transmission over the PMD of the fiber will make a request, in 2002 ITU-T SG15 meeting, the United States has put forward to 40Gbit / s system, the introduction of a new type of fiber (G.655.C) of the proposal and PMD transmit its recommendations in depth a number of issues, perhaps the near future there will be a dedicated 40Gbit / s optical fiber types.
(2) to achieve ultra-long haul transmission
Non-relay transmission is ideal for the backbone transmission network, at present some companies have been able to put in the use of dispersion techniques to achieve the 2000 ~ 5000km relay radio transmission. Some companies are to further improve the optical indicators, the use of Raman optical amplification technology, a greater extension of the distance optical transmission.
(3) to adapt to the use of DWDM technology
At present, 32 × 2.5Gbit / s DWDM system has been the use of, 64 × 2.5Gbit / s and 32 × 10Gbit / s system has been developed and made good progress. Large-scale use of DWDM systems, optical fiber non-linear indicator of a higher demand. ITU-T on the non-linear optical properties and test methods for the standard (G.650.2) has been completed recently, when the fiber is a clear indicator of non-linear test, the effective area of the fiber will be the corresponding indicators, especially for G.655 non-linear optical properties of the requirements will be further improved.
1.2 sub-standard optical fiber to promote the application of accurate
ITU Telecom World 2000, the General Assembly approve the original G.652 standard fiber-optic re-divided into G.652.A, G.652.8 and G.652.C 3 types of fiber; will be re-divided into G.655 fiber G.655.A and G .655. B two types of fiber. This breakdown of the standard optical fiber to promote the use of accurate, detailed standards and also increased the number of optical indicators (such as some of the geometric parameters of optical tolerances become smaller), a clear network of different levels and different transmission system used in the different indicators of fiber (such as the value of the provisions of PMD), and put forward the concept of a number of new indicators (such as "vertical dispersion uniformity", etc.),
Rational use of optical fiber made of a very good role. All of these proposed amendments, the emergence of sub-recommendations and the drafting of the proposed new child, have meant that optical sorting and indicators, there are certain improvements in testing methods, or have an important upgrade; have marked improvement in the quality requirements of optical fiber, or the use of direction The adjustment is worth noting that the new trend of optical fiber technology.
1.3 in the emerging new type of optical fiber
In order to adapt to the needs of the market, fiber optic technology in the continuous improvement of indicators, a variety of new optical fiber in the constantly emerging, while large companies are stepping up the development of new varieties.
(1) for a new type of long-distance telecommunications long-distance high-capacity fiber-optic
Mainly large effective area and low maintenance of a new type of dispersion G.655 fiber, the PMD value is extremely low, enabling the capacity of existing transmission systems to easily upgrade to 10 ~ 40Gbit / s, and to facilitate the use of distributed fiber drawing Cayman effect magnified, so that optical signal to extend the transmission distance significantly. Such as Corning Pure Mode PM introduced new series of fiber-optic transmission and use of polarized composite cladding for 10 Gbit / s over DWDM system, allegedly in the Raman amplifier is suitable for the development and application. Alcatel cable introduced Teralight Ultra optical fiber,
It is reported that has been transmitted over 100km length of single-channel 40Gbit / s, a total capacity of 10.2 Tbit / s of the record. Developed some negative dispersion of large effective area fiber, non-linear indicator of increased requirements and simplified the dispersion compensation program, in the long-distance transmission of non-renewable to show good performance, in the long submarine cable distance communication was also very effective.
(2) a new type of communication for Metropolitan Area Network low water peak fiber
MAN need to consider simplifying the design of equipment and reduce costs, but also need to consider the non-wavelength division multiplexing technology (CWDM) the possibility of application. Low water peak fiber in an extension of 1360 ~ 1460nm band has been greatly expanded so that the bandwidth to CWDM systems have been greatly optimized, increasing the transmission channel, an increase of transmission distance. MAN may be some of the design not only requires a low water peak fiber, also called fiber with negative dispersion value, on the one hand, the light source can be offset by the positive dispersion optical devices, on the other hand, can be combined to make use of G.652 fiber and negative dispersion fiber or G.655 standard optical fiber, using it as dispersion compensation,
So as to avoid the complexity of the design of the dispersion compensation cost savings. If in future fiber-optic metropolitan area network technology used in Raman amplification, the network will have a distinct advantage. But, after all, the norms of MAN is not very mature yet, so the specifications of fiber optic Metropolitan Area Network MAN mode will change as the ever-changing.
(3) for a new type of local area network multi-mode fiber
LAN and as a result of the rapid development of CPN, a large number of integrated wiring system has also been adopted to replace the multi-mode fiber-optic digital cable, multimode fiber, therefore the market share will gradually increase. The choice of multi-mode optical fiber, transmission distance is shorter because the local area network, although the multi-mode fiber single-mode fiber prices than your 50% ~ 100%, but it is supporting the use of optical devices light-emitting diode, the price is much cheaper than laser and multi-mode fiber has a larger core diameter and numerical aperture, easy to connect with the coupling, the corresponding connectors, couplers and other components at much lower prices. ITU-T has yet to accept the 62.
5/125μm multimode fiber-based standards, but because of the needs of local area network development, it is still widely used. And ITU-T recommendation G.651 fiber, that is, the standard 50/125μm multimode fiber, and its smaller core diameter, coupling with the corresponding more difficult to connect, although in some European countries and Japan, there are some applications, but in North America and seldom used in most countries in Europe. To solve these problems, the current has carried out some improvements, the development of a new type of 5O/125μm optical gradient (G1) optical fiber, optical fiber 50/125μm from the traditional core of the gradient refractive index distribution, the bandwidth will be normal distribution adjusted to cope with the 850nm
1300nm and the use of two windows, which may improve the local area network using optical fiber 50/125pm to find new markets.
(4) uncertainty of the air-core optical fiber
It is reported that some U.S. companies and university laboratories are developing a new air-core optical fiber, that is just enough air in the fiber-optic transmission. In theory, the fiber core does not reduce the attenuation, an increase of communication distance, to prevent interference caused by the dispersion phenomenon, can support more bands, and it allows more optical power into the expected communications capacity can reach 100 times the current optical fiber. Europe and Japan, some people in the industry are very concerned about the development of this technology, an increasing number of studies have proved hollow fiber seems to be possible. If it can be practical, the existing optical fiber system will be able to resolve the issue of long-distance transmission,
And greatly reduce the cost of optical communication. However, this fiber will use many thorny issues, such as the stability of optical fiber, the performance of lateral pressure and bending, such as increased wear and tear. Therefore, the use of this fiber at the scene needs to be done to explore further.