Development Status and Prospect of China's Optical Fiber and Cable Industry
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First, the status quo of China's development of fiber optic cable
Ordinary single-mode fiber is the most commonly used fiber. With the development of optical communication systems, optical relay distance and single wavelength channel capacity increase, the performance of G..652.A optical fiber may be further optimized, and the low attenuation coefficient in the 1550 rim region is not fully utilized and optical fiber. The lowest attenuation coefficient and zero dispersion point are not in the same area. The cutoff wavelength shifted single-mode fiber conforming to ITUTG.654 and the dispersion shifted single-mode fiber complying with the G..653 specification achieve such an improvement.
2. Core network cable
China has fully adopted fiber optic cables on trunk lines (including national trunk lines, provincial trunk lines, and regional trunk lines). Among them, multimode optical fibers have been eliminated and all use single-mode optical fibers, including G..652 fiber and G..655 fiber. Although G..653 fiber was used in China, it will not be developed in the future. The G..654 fiber has not been used in China's terrestrial cable because it can not greatly increase the fiber system capacity. The discrete optical fiber is used in the trunk cable, and the optical fiber tape is not used. Mainline cables are mainly used outdoors. In these optical cables, the tight-jacketed tiered and skeleton structures that have been used in the past have been discontinued.
3. Access network cable
The distance of the optical cable in the access network is short, the branches are numerous, and the frequency division and insertion are frequent. In order to increase the capacity of the network, the number of optical fibers is usually increased. Especially in the city pipelines, due to the limited inner diameter of the pipe, it is important to increase the optical fiber assembly density of the optical cable and reduce the diameter and weight of the optical cable while increasing the number of optical fibers. The access network uses G..652 common single mode fiber and G..652.C low water peak single mode fiber. Low-water peak single-mode fiber is suitable for dense wavelength division multiplexing and is currently used in small quantities in China.
Indoor fiber optic cable
Indoor fiber optic cables often need to be used for the transmission of voice, data and video signals at the same time. And it may also be used for telemetry and sensors. The author thinks that the indoor optical cable referred to by the International Electrotechnical Commission (IEC) in the category of optical fiber cables should include at least two parts of the optical fiber cable used in the office and the integrated wiring. The office optical fiber cloth is placed in the central office or other telecommunication rooms, and the deployment is closely ordered and the position is relatively fixed. In combination with cabling, the optical fiber cable is placed in the user's room and is mainly used by the user. Therefore, its vulnerability should be more strictly considered than that of the office optical cable.
5. Communication cables in power lines
Fiber optics are dielectrics, and fiber optic cables can also be made completely media, completely free of metals. Such an all-dielectric fiber cable will be the most ideal communication line for the power system. There are two types of all-dielectric fiber cables used for laying power line poles: the all-media self-supporting (ADSS) structure and the winding-type structure used on overhead ground wires. ADSS fiber optic cable has been widely used in the transformation of China's power transmission system because it can be deployed alone and has a wide range of adaptability. The recent demand for ADSS fiber optic cables in China is a hot product at present.
Second, the development trend of optical fiber communication technology
For optical fiber communications, ultra-high speed, large capacity, and ultra-long-distance transmission have always been the goals pursued by people. All-optical networks are also people's unrelenting dreams.
1. Ultra-large-capacity, ultra-long-distance transmission technology Wavelength-division multiplexing technology has greatly improved the transmission capacity of optical fiber transmission systems, and has broad application prospects in the future of trans-ocean optical transmission systems. In recent years, the wavelength division multiplexing system has developed rapidly. At present, the 1.6Tbit/WDM system has been widely used commercially, and the all-optical transmission distance has also been greatly expanded. Another way to increase the transmission capacity is to adopt optical time division multiplexing (OTDM) technology. Compared with WDM, which increases the transmission capacity by increasing the number of channels transmitted in a single optical fiber, OTDM technology improves the transmission capacity by increasing the single-channel rate. It achieves a maximum single-channel rate of 640 Gbit/s.
OTDM and WDM alone improve the capacity of optical communication systems. After all, it is possible to multiplex multiple OTDM signals for wavelength division multiplexing, thereby significantly increasing transmission capacity. Polarization multiplexing (PDM) technology can significantly reduce the interaction of adjacent channels. Since the return-to-zero (RZ) coded signal has a smaller duty cycle in the ultra-high speed communication system, the requirement for dispersion management distribution is reduced, and the RZ coding method has a strong ability to adapt to nonlinearity and polarization mode dispersion (PMD) of the optical fiber. Therefore, nowadays the ultra-large capacity WDM/OTDM communication system adopts RZ code transmission. The key technologies that need to be solved in WDM/OTDM hybrid transmission systems are basically included in the key technologies of OTDM and WDM communication systems.
2. Optical soliton communication. Optical soliton is a kind of special ps order ultrashort optical pulse. Because it is in the anomalous dispersion region of the fiber, the group velocity dispersion and non-linear effects balance each other. Therefore, after long-distance transmission of the optical fiber, the waveform and velocity remain unchanged. Optical soliton communication is the use of optical soliton as a carrier to achieve long-distance undistorted communications, and in the case of zero errors, information transmission can reach thousands of miles away.
The future prospects of optical soliton technology are: ultra-long-distance high-speed communication in terms of transmission speed, ultra-short pulse control technology in the time domain and frequency domain, and ultrashort pulse generation and application technology to increase the current rate of 10-20 Gbit/s to More than 100Gbit/s; using retiming, shaping, regenerative technology and reducing ASE in increasing transmission distance, optical filtering increases the transmission distance to more than 100,000km; in high-performance EDFA is to obtain low noise and high output EDFA. Of course, there are still many technical difficulties in actual optical soliton communication. However, the breakthroughs that have been made so far have led people to believe that optical soliton communication is used in ultra-long-distance, high-speed, and high-capacity all-optical communications, especially in submarine optical communication systems. Has a bright development prospects.
3. All-optical network. The future high-speed communications network will be all-optical network. All-optical network is the highest stage and the ideal stage for the development of optical fiber communication technology. The traditional optical network achieves full photonization between nodes, but electrical components are still used at the nodes of the network, which limits the further increase of the total capacity of the current communication network trunk. Therefore, a true all-optical network has become a very important issue.
All-optical networks use optical nodes instead of electrical nodes. Nodes are also all-photonized. Information is always transmitted and exchanged in the form of light. Switch-to-user information processing is no longer performed on a bit-by-bit basis, but routing is determined based on its wavelength.
At present, the development of all-optical networks is still in its early stages, but it has shown good development prospects. Judging from the development trend, the formation of a true optical network layer based on WDM technology and optical switching technology, the establishment of a pure all-optical network, elimination of electro-optical bottlenecks has become an inevitable trend in the future development of optical communications, it is the future of information networks The core is also the highest level of communication technology development, and it is an ideal level.
Third, the conclusion
Optical fiber communication technology as an important supporting platform for information technology will play an important role in the future information society. Although it has experienced the "winter" of global optical communication, the optical communication market will continue to show an upward trend in the future. From the perspective of the development trend of modern communications, optical fiber communications will also become the mainstream of future communications development. The era of real all-optical networks that people expect will also come in the near future.
Double-sided PCBs are one of the most common kinds available. While single-sided PCBs have one conductive surface, double-sided PCBs have a conductive layer on each side. A dielectric layer is surrounded by circuit copper layers and solder mask on both sides. Vias allow manufacturers to create traces on both sides that route around each other and connect between layers. Manufacturers use double-sided PCBs for products that need a beginner to intermediate level of circuit complexity. This type of PCB doesn`t offer as much circuit complexity or density as multilayer PCBs, but they work as an affordable option in numerous applications
Double-Sided PCB, Double-Sided PCB With Enig Via In Pad PCB, FR4 PCB With Matt Black Soldermask
Storm Circuit Technology Ltd , http://www.stormpcb.com