Number of visits: date: 2022-08-01
1. Common optical fiber
With the development of optical communication system, optical relay distance and single-wavelength channel capacity increase,G.. The performance of the 652.A fiber may be further optimized, as the low attenuation coefficient in the 1550RIM region is not fully utilized and the lowest attenuation coefficient and zero dispersion point of the fiber are not in the same region. Cut-off wavelength shifted single-mode optical fibers conforming to ITUTG.654 and conforming to G.. The dispersion-shifted single-mode fiber specified in 653 achieves such an improvement.
2. Core network cable
China has been in the trunk line (including the national trunk line, the provincial trunk line and the regional trunk line) on the comprehensive use of optical cable, multi-mode optical fiber has been eliminated, all single mode optical fiber, including G.. 652 Optical fiber and G.. 655 optical fiber. G.. Although 653 optical fiber once adopted in our country, but will not be developed in the future. G.. 654 optical fiber because it can not greatly increase the capacity of optical fiber system, it is not used in our land optical fiber. Discrete optical fibers are used in trunk optical cables, not fiber ribbons. Mainline optical cables are mainly used outdoors, where tight-sleeve stranded and skeleton structures have been used, but are no longer in use.
3. Optical cable for access network
In the access network, the cable distance is short, branches are many, and the insertion is frequent. In order to increase the capacity of the network, it is usually to increase the number of fiber cores. Especially in the city pipeline, due to the limited inner diameter of the pipeline, it is very important to increase the density of optical fiber assembly and reduce the diameter and weight of optical fiber while increasing the number of fiber cores. Access network use G.. 652 Common Single Mode Optical fiber and G.. 652.C Low water peak single mode fiber. Low water-peak single mode optical fiber is suitable for dense wavelength division multiplexing and is used in our country.
4. Indoor optical cable
Indoor optical cables are often used for simultaneous transmission of voice, data and video signals. It may also be used for telemetry and sensors. International Electrotechnical Commission (IEC) in the classification of optical cables referred to the indoor optical cable, the author believes that at least should include intra-office optical cable and cable for cabling. Local optical cables are placed in the central office or other telecommunications equipment rooms in a tight and orderly manner and in a relatively fixed position. Combined cabling optical cable is laid in the user's room, mainly used by the user, so its vulnerability should be more strictly considered than local optical cable.
5. Communication optical cable in power line
Optical fiber is dielectric, optical fiber can also be made into a full medium, completely metal free. Such all-medium optical cable will be the most ideal communication line for power system. There are two kinds of all-medium optical cables used for power pole laying: the all-medium self-supporting (ADSS) structure and the winding structure used for overhead ground wire. ADSS optical cable is widely used in the transformation of power transmission system in China because it can be distributed alone and has a wide range of adaptation. ADSS cable is a popular product in the near future.
Second, the development trend of optical fiber communication technology
For optical fiber communication, ultra-high speed, ultra-large capacity and ultra-long distance transmission have always been the goal of people's pursuit, and the all-optical network is also the dream of people's unremitting pursuit.
1.Ultra-large capacity and ultra-long distance transmission technology WDM technology greatly improves the transmission capacity of optical fiber transmission system, and has broad application prospects in the future cross-sea optical transmission system. In recent years, WDM systems have developed rapidly. At present, 1.6Tbit/ WDM systems have been widely used, and the all-optical transmission distance is also greatly expanded. Another way to improve the transmission capacity is to use optical time division multiplexing (OTDM) technology. Unlike WDM, which improves the transmission capacity by increasing the number of channels transmitted in a single fiber,OTDM technology improves the transmission capacity by increasing the single channel rate, and the maximum single channel rate achieved by OTDM is 640Gbit/s.
After all, it is limited to improve the capacity of optical communication system only by OTDM and WDM, so multiple OTDM signals can be wavelength-division multiplexed to greatly improve the transmission capacity. Polarization multiplexing (PDM) technology can obviously weaken the interaction between adjacent channels. Due to the small duty cycle of zeroing (RZ) coded signals in ultra-high speed communication systems, which reduces the requirements for dispersion management and distribution, and the strong adaptability of RZ coding to the nonlinearity and polarization mode dispersion (PMD) of optical fibers, the current ultra-large capacity WDM/OTDM communication systems basically adopt RZ coding transmission mode. The key technologies that need to be solved in WDM/OTDM hybrid transmission system are basically included in the key technologies of OTDM and WDM communication system.
2. Optical soliton communication. Optical soliton is a special ultra-short optical pulse of the order of PS. Because it is in the anomalous dispersion region of optical fiber, the group velocity dispersion and nonlinear effect balance each other, so the waveform and velocity remain unchanged after the long-distance transmission of optical fiber. Optical soliton communication is to use optical solitons as carriers to achieve long distance communication without distortion, and information transmission can reach tens of thousands of miles in the case of zero bit error.
The future prospect of optical soliton technology is: in terms of transmission speed using ultra-long distance high-speed communication, time domain and frequency domain ultra-short pulse control technology and ultra-short pulse generation and application technology to increase the current rate of 10-20 gbit /s to more than 100Gbit/s; In the aspect of increasing the transmission distance, retiming, shaping, regeneration technology and reducing ASE are adopted. Optical filtering improves the transmission distance to more than 100000km. In terms of high performance EDFA is to obtain low noise and high output EDFA. Of course, there are still many technical difficulties in practical optical soliton communication, but the breakthrough made so far makes people believe that optical soliton communication has a bright development prospect in ultra-long distance, high speed and large capacity all-optical communication, especially in submarine optical communication system.
3. All-optical network. The high-speed communication network of the future will be all-optical. All-optical network is the highest and ideal stage in the development of optical fiber communication technology. The traditional optical network realizes the all-optical network between nodes, but still uses the electrical components at the network nodes, which limits the further improvement of the total capacity of the communication network. Therefore, the real all-optical network has become a very important topic.
In all-optical network, optical nodes replace electrical nodes, and the nodes are all optical. Information is always transmitted and exchanged in the form of light. The switch no longer processes user information by bit, but decides the route according to its wavelength.
