On the branch and development trend of optical fib

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With the development and wide application of dense wavelength division multiplexing (DWDM) technology and optical fiber amplification technology, including erbium-doped fiber amplifier (EDFA), distributed Raman fiber amplifier (drfa), semiconductor amplifier (SOA) and optical time division multiplexing (OTDM) technology, optical fiber communication technology continues to develop towards higher speed and larger capacity communication systems, The advanced optical fiber manufacturing technology can not only maintain stable and reliable transmission and sufficient redundancy, but also meet the needs of optical communication for large broadband and reduce nonlinear damage

multimode fiber

the center core of multimode fiber is thick (50 or 62.5 μ m) It can transmit multiple modes of light. The common multimode fiber is: 50/125 μ M (European standard gb/t 12606 magnetic flux leakage testing method for steel pipes), 62.5/125 μ M (American Standard)

in recent years, the application of multimode optical fiber has increased rapidly, mainly because the world's optical fiber communication technology will gradually shift to in-depth development, and the practicality of parallel optical interconnection components has also greatly promoted the rapid growth of the short-range multimode optical cable market, thus making the market share of multimode optical fiber continue to rise. With the establishment of Gigabit Ethernet, Ethernet will also be upgraded from Gbps to 10Gbps ultra-high rate. 10Gbps Ethernet standard (ieee802.3ae) was introduced in the first half of 2002. The continuous progress of communication technology has greatly promoted the development of multimode optical fiber

full wave optical fiber

with the continuous expansion of people's demand for optical fiber bandwidth, the communication industry has been trying to find a way to eliminate the "water absorption peak". In essence, the manufacturing technology of all wavefiber is a special production technology by eliminating the "water absorption peak" of OH ions as much as possible, which reduces the attenuation peak of ordinary standard single-mode fiber near 1383nm to a sufficiently low level. In 1998, Lucent developed a new optical fiber manufacturing technology, which can eliminate the oh ion in the optical fiber glass, so that the optical fiber loss is completely controlled by the characteristics of the glass, "water absorption peak" is basically "flattened", so that the optical fiber is at 1280? All wavelength ranges of 1625nm can be used for optical communication. Therefore, the problem of full wave optical fiber manufacturing technology has been gradually solved. So far, many manufacturers have been able to produce full wave fiber for communication, such as Lucent's all wave fiber, Corning's smf-28e fiber, Alcatel's ESMF enhanced single-mode fiber, and Fujikura's lwpfiber fiber

in April 2000, in order to adapt to the latest progress of optical fiber product technology, ITU made a large-scale revision of the G.652 single-mode optical fiber standard, which was officially finalized in October, corresponding to the classification number b1.3 of IEC (International Electrotechnical Commission). ITU-T defined "full wave optical fiber" as g.652c optical fiber, It is mainly applicable to the SDH transmission system specified in G.957 of ITU-T, the single channel SDH transmission system with optical amplification specified in g.691, and the g.692 wavelength division multiplexing transmission system with optical amplification of ITU-T up to STM-64 (10gb/s). For high-speed transmission in the 1550nm wavelength region, wavelength dispersion adjustment is usually required

full wave optical fiber will have great potential in metropolitan area construction. From the perspective of network operators, with full wave fiber, coarse wavelength division multiplexing technology can be adopted, and its channel spacing is about 20nm. At this time, a large bandwidth can still be provided for the network. At the same time, the performance requirements of filters and lasers are greatly reduced, which greatly reduces the construction cost of network operators. The emergence of full wave optical fiber makes a variety of optical communication services more flexible. Because there is a wide wave band for communication, we can divide the wave band of full wave optical fiber into different communication service segments and use them respectively. It can be predicted that this kind of full wave optical fiber will be widely used in the construction of small and medium-sized cities in the future

human desire to pursue high-speed and broadband communication networks is endless. With the current exponential growth in bandwidth demand, full wave optical fiber is receiving more and more attention from the industry, and its many advantages have been widely accepted by the communication industry

polymer optical fiber

at present, the main line of communication has realized the communication based on quartz optical fiber. However, in the access and fiber to the home (FTTH) projects, quartz optical fiber has encountered great difficulties. Because the core of quartz optical fiber is very thin (6? 10 μ m) , the coupling and interconnection of optical fibers are faced with technical difficulties, because high-precision alignment technology is required, so it is a difficult problem for access users with short distance and many contacts. However, polymer optical fiber (POF) can use cheap and simple injection connectors because of its large core diameter (0.2? 1.5mm), good toughness and flexibility, large numerical aperture, low-cost laser source can be used, and there is a low loss window in the visible light region, which is suitable for access. Polymer optical fiber is the most promising transmission medium in FTTH engineering at present

polymer optical fibers are divided into two categories: multi-mode step si-pof and multi-mode gradual change GI-POF. Due to the serious mode dispersion of sipof, the transmission bandwidth is similar to that of twisted pair copper wire, which is limited within 5MHz. Even within a very short communication distance, it can not meet the requirements of FDDI, SDH, B-ISDN communication standards, while the refractive index distribution of gipof core is parabolic, so the mode dispersion is greatly reduced, and the signal transmission bandwidth can reach more than 2.5Gbps within 100m, In recent years, gipof has become the main direction of POF research. Recently, NiO theoretically predicted that the theoretical loss limit of amorphous perfluoropolybutylene vinyl ether at 1300nm is 0.3db/km, and the loss at 500nm can be as low as 0.15db/km, which is completely comparable to the loss of quartz fiber. Orgio et al. Reported that the data transmission rate of 100m perfluorinated gipof has reached 11gbps. Therefore, gipof may become an ideal transmission medium for access, users, etc

photonic crystal fiber

photonic crystal fiber (PCF) was proposed by sell et al in 1992. For quartz optical fiber, the structural feature of PCF is that the air holes are evenly arranged in the middle along the axis. In this way, from the end face of the optical fiber, there is a two-dimensional periodic structure. If one of the holes is damaged and missing, there will be defects. Using this defect, light can spread in it. PCF is different from ordinary single-mode fiber. Because it is composed of a single quartz material with periodically arranged air holes, it is called holeyfiber or micro structuredfiber. PCF has special dispersion and nonlinear characteristics, and will be widely used in the field of optical communication

a striking feature of PCF is that it has a reasonable structure and the ability to support single-mode transmission at all wavelengths, that is, the so-called "endleslysingle mode" feature, which has been a good theoretical explanation for the year-on-year sharp increase of 51%. This needs to meet the condition that the air hole is small enough, and the ratio of air hole diameter to hole spacing must not be greater than 0.2. PCF with large air hole will be the same as ordinary optical fiber, and multimode phenomenon will appear in the short wavelength region

Another characteristic of

pcf is that it has strange dispersion characteristics. Now people have successfully generated 850nm optical solitons in PCF, and it is expected that the wavelength will be reduced in the future. PCF may play an important role in flat dispersion compensation of ultra wide WDM in the future

Danish crystalfibera/s, the world's leading company in the commercialization of PCF products, recently launched a new series of photonic crystal fiber products. One is the hollow "air guiding photonic bandgap crystal fiber". The core of this crystal fiber is hollow, and air is used as a waveguide, so that light can be transmitted in a special energy band gap. The other is "double clad high NA Yb fiber", which can be used in fiber lasers or fiber amplifiers. In addition, because of its photosensitivity, fiber gratings can also be engraved on it

problems faced by communication optical fiber

at present, optical fiber needs two gratings, and there are still many problems to be solved in optical communication applications. Such as dispersion and dispersion, finite dispersion and small dispersion slope, negative dispersion, polarization mode dispersion, nonlinearity, bending loss of effective area in large core region, contradiction faced by comprehensive optimization, effective area and dispersion slope, negative dispersion and loss, etc. However, it is reasonable to believe that with the continuous progress of optical communication technology, appropriate solutions will be found to these problems. (end)

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