Who knows the manufacture and technology of communication optical cable?

1970, corning company took the lead in developing the world's first timely glass fiber with attenuation less than 20dB/km. This data of 20dB/km is considered as the threshold of optical fiber used for communication at that time, and it was also determined by Dr. Gao Kun's calculation. At that time, the attenuation of existing glass fiber was as high as 1000dB/km, which was too high to be used for communication. Shortly thereafter, in 1970, the first semiconductor laser realized room temperature operation. In this way, the problems of light source and transmission medium are expected to be solved, and the whole world is excited about it! Since then, the prelude of optical fiber research and optical fiber communication research has been opened, and the development of modern optical fiber communication has begun.

When the international research on optical fiber communication kicked off, it was the time when Wuhan Institute of Posts and Telecommunications was prepared for construction. Therefore, at the beginning of the establishment of Wuhan Institute of Posts and Telecommunications (WRI) (1974), the research on optical fiber communication was determined as the main direction. Fiberhome Communication Technology Co., Ltd. was founded by WRI, and the optical fiber and cable industry of Fiberhome Communication Technology Co., Ltd. was developed on the basis of WRI optical fiber and cable research department. With the rapid development of optical cable industry in optical fiber communication technology Co., Ltd., the development history of multimode optical fiber, one of the main products of optical fiber communication, is briefly reviewed and its development trend is prospected.

Second, the history and development of multimode fiber

Looking back on the development of multimode fiber in the past 30 years, it can be roughly divided into three stages.

The first stage, 197 1 ~ 1980, is the research and development period of multimode fiber. During this period, the traditional double crucible process was gradually eliminated in the world, and four new chemical vapor deposition preform processes, such as MCVD, OVD, VAD and PCVD, were developed. From multi-component oxide glass fiber to time-sensitive glass fiber: The transmission theory and fiber design of multimode fiber are studied, and the key technologies to optimize preform process and improve bandwidth of multimode fiber by analyzing the measurement results of differential mode delay (DMD) are emphatically developed. The multimode optical fiber communication system is tested in the field. Establish the industry standard of 50/ 125mm gradient multimode fiber (hereinafter referred to as 50 -MMF). 50 mm MMF put into mass production. Representative ones are Corning's Wilmington Optical Fiber Factory 1979, which was put into operation in June, and T Company's at & Atlanta Optical Fiber Factory 1979 was expanded in April and put into operation the following year. 1980 The global annual output of optical fiber is less than 65438+ million kilometers, and 100% is multimode fiber. This is the beginning of the optical fiber industry. In the following 20 years, the annual output of MMF increased rapidly, reaching 4 million km in 2000 (see table 1).

The second stage, 198 1 ~ 1995, is the development period of practical multimode fiber and the addition of new varieties. Worldwide, a practical trunk optical fiber communication system has been established using 50 -MMF. However, in the first few years of this period (1983 ~ 1984), the technology of single-mode fiber (G.652A fiber) was mature, and the position of 50 -MMF in the inter-office trunk fiber communication system was quickly replaced by single-mode fiber. Since then, 50 -MMF has turned to the field of data transmission, mainly used in LAN. At that time, in order to reduce the cost of LAN system as much as possible, low-priced light-emitting diodes (LEDs) were widely used instead of expensive semiconductor lasers (LD) as light sources. The divergence angle of LED is much larger than LD, but the core diameter and numerical aperture of 50φ-MMF are relatively small at that time, which is not conducive to efficient coupling with LED. In order to make the connection and coupling easier and make the optical power coupled into the fiber more powerful, gradient multimode fibers with larger core diameter and larger numerical aperture have been developed internationally, such as 62.5/ 125, 80/ 125, 100/ 140. Shortly thereafter, most of the market share of 50 MMF was replaced by the emerging 62.5/125mm gradient multimode fiber. However, multimode optical fibers such as 80/ 125, 100/ 140 have not been widely used for many reasons, such as large bending loss, high manufacturing cost and special cladding diameter. During this period, multimode fiber gradually replaced the traditional copper wire and coaxial cable, and became the preferred physical medium for modern ultra-high-speed LAN systems.

In the third stage, 1996-2002, the research and development of multimode fiber entered the latest active period. It is estimated that the active period will last until 20 10. During this period, the local area network system developed to the ultra-high speed above GB/S, and IEEE adopted the Gigabit Ethernet standard in June 1998. In June 2002, the 10Gb/s Ethernet standard was just passed. This ultra-high-speed LAN system must use laser as light source and a new generation of high-performance multimode fiber. In addition to the 10Gb/s Ethernet standard, there are many industrial standards that will adopt the new generation of multimode fiber (see Table 3).

Corning Company of the United States, OFS Company of Lucent Company and Dellacqua Company of the Netherlands have all introduced this new generation of multimode fiber samples. The promulgation of various industrial standards provides a unified foundation for the development, production and application of this kind of optical fiber, and more optical fiber manufacturers will invest in the development and production of a new generation of multimode optical fiber. It is predicted that after 2002, it will be the golden age for multimode fiber to achieve greater development.

3. Development and application of multimode optical fiber for beacon communication.

WRI is the first company in China to develop timely glass multimode optical fiber by MCVD process. Table 4 summarizes the early development of WRI multimode fiber.

Since then, WRI has increased its investment in the research of PCVD equipment and technology, and has successively completed the research of PCVD equipment and rod-making technology (1990). Research on Manufacturing Technology of Large Preform by High Efficiency PCVD Method (1992): Long PCVD optical fiber preform manufacturing system research (1995) and other projects, obtained a number of related patent authorization. The above research results greatly enrich the technical strength and development potential of WRI in multimode fiber.

1996, China issued and implemented the data optical fiber communication industry standard yd/t 816-1996, which was drafted by WRI. The publication and implementation of this standard has promoted the standardized development of the domestic data optical fiber market. Since WRI successfully developed 62.5/ 125 data fiber in 1998 1 year and passed the ministerial appraisal, it was mass-produced with self-made PCVD equipment and passed the appraisal procedure. The products are of high quality and good reputation. In addition to domestic demand, it is also exported to South Korea, India and other countries, and is well received by domestic and foreign users. The LAN system established by optical cable produced by WRI Data Optical Fiber Company is widely used in institutions, schools, factories and network companies. The economic and social benefits are remarkable.

Since the establishment of 1999, Fiberhome Communication has taken the industrialization of multimode optical fiber as an important task and implemented a leap-forward development strategy. First of all, in the original pilot plant, by improving equipment performance, adding new PCVD equipment and improving process technology, the ratio of optical fiber production and sales in 200 1 year to 1999 increased by five times. At the same time, the newly-built optical fiber factory in Wuhan Optics Valley, China will be put into operation soon. In addition to the mass production of single-mode optical fiber, the latest generation of PCVD equipment will be used to produce high-performance multimode optical fiber, and the production capacity will be increased by 4 ~ 5 times on the existing basis. DMD measurement is an indispensable technology in the research of new generation 50/ 125 multimode optical fiber. Fiberhome communication is fully prepared. R&D personnel collected and studied relevant technical data, purchased DMD measuring equipment, and studied the process of eliminating RIP defects.

Four. Summary and prospect

This paper reviews the development of multimode fiber in the past 30 years. At present, it is the latest active period of multimode fiber research and development, and the application of multimode fiber in short-distance communication systems such as local area network has gone through more than 20 years. With the acceleration of the information process of human society, the transmission rate and capacity of these systems are also increasing rapidly. At high speed, compared with coaxial cable and copper wire, the technical and economic advantages of optical cable are increasingly obvious. Therefore, the application of multimode fiber in local area network will continue to expand. In addition, due to the development of the new generation of 50/ 125 multimode optical fiber, the application of multimode optical fiber will not only be limited to local area network, but also be widely used for communication equipment interconnection between storage area network (SAN) and wide area network/metropolitan area network (WAN/MAN) exchange offices. The industry has shown great interest in studying various new technologies to improve MMF capacity. Using these new technologies, it is possible to increase the effective bandwidth of MMF by dozens of times. It is predicted that there will still be some new technological breakthroughs after the new generation of multimode fiber.

It is worth noting that before the introduction of IEEE 802.3z Gigabit Ethernet standard, single-mode optical fiber was rarely used in LAN. While adopting multimode fiber, the standard also adds traditional single-mode fiber for transmission within 5 kilometers. In the newly released 10Gb/s Ethernet standard, conventional single-mode optical fiber is also included for transmission within 40km. It is predicted that with the upgrading of network speed and the expansion of network scope, more traditional single-mode optical fiber or even more advanced single-mode optical fiber, such as low water peak optical fiber, may be used. Some companies have introduced single-mode optical fiber data transmission solutions working at short wavelengths (850 nm and 1200 nm). Because the life of optical fiber network is much longer than that of 10 years, in some practical projects, a hybrid optical cable of multimode fiber and single-mode fiber has been laid, and single-mode fiber is used as dark fiber for future upgrade. A foreign company has introduced a new type of optical fiber sample, which combines multimode fiber and single-mode fiber, called combined MM-SM-fiber. The fiber has a convex core refractive index distribution, that is, a single-mode core concentric with the multimode fiber protrudes from the center of the multimode fiber. When the two ends of the optical fiber are connected by MMF, the optical fiber works in multimode state; When both ends of the fiber are connected with SMF, the fiber works in single mode. Its characteristic is easy to upgrade to single mode.

In the LAN environment, the total cost of multi-mode system is still lower than that of single-mode system at present and in the future. From 2000 to 20 10, the global market share of multimode fiber in LAN is about 70%, with an average annual growth rate of over 2 1%. In the future LAN market, multimode optical fiber will not only continue to compete with copper wire, but also with plastic optical fiber and single-mode optical fiber. This requires multimode fiber manufacturers to continuously improve productivity, reduce production costs, and actively adopt new technologies to develop new products and solutions that meet market demand. Fiberhome communication has a long and brilliant development history in multimode optical fiber, has the advantages of integrating photoelectric subsystem-photoelectric device-optical fiber cable, and has established a soaring platform. We believe that the optical fiber and cable industry of Fiberhome Communication Technology Co., Ltd. will carry forward the past and create greater glories.