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Plastic optical fiber product development in brief

One, preface

Since the industry pioneered fiber optic communication technology, to summarize, fiber optic communication than the traditional electric copper communication has three major advantages: First, the communication capacity; Second, anti-electromagnetic interference, better confidentiality; Third, light weight and can save a lot of copper, such as paving 1,000 kilometers of 8-core fiber optic cables than the same length of 8-core cables can save 1,100 tons of copper, 3,700 tons of lead. 8-core cable can save 1100 tons of copper, 3700 tons of lead. Therefore, fiber optic cable once introduced by the communications industry welcome, bringing a revolution in the field of communications and a round of investment and development boom.

Despite the above advantages of glass fiber, but it has an Achilles' heel is the low strength, poor deflection resistance, and radiation resistance is not good. Therefore, over the past 20 years, the industry has not stopped on the fiber of other materials instead of research and development, which is currently the industry's most interested in the development of plastic optical fiber research and development is one of the most interested in the field of research, has made greater progress, there have been commercial products have come out, is now widely used in automobiles, CD players, industrial electronic systems, small optical disk systems and personal computers. In the future, there will be many areas will use plastic optical fiber, such as sensors, photonic crystal fiber.

Two, the advantages of plastic optical fiber

Plastic optical fiber compared with glass fiber, although poor light transmission, light loss is larger, the initial general 300 dB / km, transmission of narrow optical band (limited to the visible region), is difficult to adapt to the needs of the multimedia communication network, but it has a light and soft, anti-flexing, high impact strength, inexpensive, irradiation, easy to process, and can be made into a large diameter (1 ~ 1). Made of large diameter (1 ~ 3 mm, to increase the angle of light, expanding the scope of use) and a series of advantages, so it is highly favored. In addition, the diameter of the central part of the light through the plastic optical fiber is about 1 mm, 100 times larger than the glass fiber, and the connection between the fiber and the connection with the terminal device such as personal machine is very easy. Therefore, plastic optical fiber installation costs are very low, the installation of a very simple alignment connection plug can be used, this plug can be produced with existing technology.

Three, plastic optical fiber product development

Plastic optical fiber research began in the 1960s. 1968, the United States DuPont used polymethylmethacrylate as the core material for the preparation of plastic optical fibers, but the optical loss is large. 1974, Japan's Mitsubishi Rayon company to PMMA and polystyrene as the core material, with a low refractive index of the fluorine plastic as the cladding to develop plastic optical fiber, the optical loss is 3500dB, the optical loss is 3,500dB, and the optical loss is 3,500dB. Its optical loss of 3500dB/km, difficult to use for communications.

In the 80's Japan, some large enterprises and universities on the preparation of low-loss plastic optical fiber has carried out a lot of research. 1980 Mitsubishi polymerization of PMMA with high-purity MMA monomer, so that the plastic optical fiber loss down to 100-200dB/km. 1983 NTT began to replace the H atom of PMMA with deuterium, so that the lowest optical loss can reach 20dB/km, and can transmit near-infrared light, and can be used for communication, and can be used to transmit the light loss. km and can transmit light waves from near infrared to visible light.

In recent years, European and Japanese companies have made important progress in the development of plastic optical fiber. They developed into a plastic optical fiber, optical loss rate has been reduced to 25 ~ 9 dB / km. Its operating wavelength has been extended to 870 microns (near infrared light), close to the practical level of quartz glass fiber. The United States developed a PFX plastic series of optical fibers, with excellent anti-irradiation properties. In addition, the United States, Boston, Massachusetts fiber optic company developed Opti-Giga plastic optical fiber is even more striking, it is not only lighter than glass, flexible, better, lower cost, and can be in 100 meters at a speed of 3 megabits per second to transmit data. This kind of fiber can also use the refraction of light or light in the fiber jump way to achieve higher transmission speed. Now the U.S., Europe and Japan have used plastic optical fiber for short-haul transmission, such as automobiles, medical equipment, photocopiers and so on.

In terms of the current production of plastic optical fiber, Japan is the world's largest producer of plastic optical fiber, however, it is Europe to promote the development of new applications of plastic optical fiber and the establishment of optical fiber inspection standards. 2001 is the second half of the second half of Europe's plastic optical fiber industry is an important stage of the development of plastic optical fibers in Europe, in the establishment of the European plastic optical fiber during the period of time, the new development of inspection and measurement of plastic optical fibers and the new development of the guidelines. The world's first dedicated Plastic Optical Fiber Application Center (POFAC) was inaugurated in Nuremberg, Germany. Germany using plastic optical fiber has developed a successful multimedia bus system MOST (24Mbit / s), and several car manufacturers have introduced the system to their products. Germany's BMW (BMW) in its new seven series of products to create a record of using 100m plastic optical fiber. The European 2001 Plastic Optical Fiber Symposium and the European Optical Fiber Communication Conference were held in Amsterdam, the Netherlands, at the same time. The German automotive industry is driving not only the use of plastic optical fibers, but also the establishment of standards for their inspection and measurement.

Japan has also established plastic optical fiber standards, but these standards are not valid for the European ****same body. Japanese industrial standards only give a model of plastic optical fiber standards, its numerical aperture of 0.5, and only 650nm a wavelength. The standard makes no mention of different excitation light conditions in plastic fibers, nor does it specify that an equilibrium mode distribution must be formed within the plastic fiber.

Previously established glass fiber test method because there will be Rayleigh scattering and is not suitable for testing plastic fibers, and now there is only a new Swiss Luciol Instruments sold a test of plastic fibers on the market.

The German Institution of Engineers and the Institute of Electrical Engineering research group has detailed the provisions of the plastic optical fiber numerical aperture, attenuation, transmission and mechanical properties, as well as environmental and life measurement methods. The establishment of plastic optical fiber test methods and standards will certainly promote the development of international trade in plastic optical fibers and eliminate trade misunderstandings.

Japan attaches great importance to the application of plastic optical fibers, as early as a few years ago, NEC, Fujitsu, Sumitomo Electric Industries, 45 optical communications, multimedia products manufacturers have jointly announced that it will *** with the realization of has been successfully developed in Japan, the practical application of plastic optical fibers. The low cost of plastic optical fiber was considered a key technology for introducing multimedia into the home, and a number of manufacturers then proceeded to set up production lines.

In 1986, Japan's F Fujitsu to PC for the core material developed SI-type heat-resistant POF, heat-resistant temperature of up to 135 degrees Celsius, attenuation of up to 450dB/km;

1990, Japan's Keio University's Assistant Professor Koike developed a successful refractive index of gradient-type plastic optical fiber, the core for the fluorine-containing PMMA, fluorine-containing cladding, with interfacial gel technology. Manufactured by interfacial gel technology. The plastic fiber attenuation below 60db/km, light source 650-1300nm, 100m bandwidth of 3GHz, transmission rate of 10Gb/s, exceeding the GI-type quartz optical fiber, and is widely regarded as a new optical communication medium for the high-speed multi-media era of optical fiber to the home;

1996, it has been proposed to establish a very low-cost subscriber network based on plastic optical fiber ATM physical layer; in 1997, NEC Corporation of Japan conducted a test of 155Mbit/s ATM, LAN.

In the 2000 OFC meeting, Japan ASAHI GLASS reported fluorinated gradient plastic optical fiber attenuation coefficient at 850nm for 41dB/km, at 1300nm for 33dB/km, the bandwidth has been up to 100MHz.km. 50m, 2.5Gbit/s high-speed transmission test was successfully carried out with this fiber and 70 degree Celsius long-term thermal aging test. The experiment concluded that the fluorinated gradient plastic optical fiber can fully meet the requirements of short-distance communication use.

From the perspective of the development of plastic optical fiber research, plastic optical fiber research focus on the following three aspects:

1. Reduce optical loss;

2. Increase the bandwidth (from SI-type to GI-type);

3. Improve the heat resistance. (Polycarbonate (PC), silicone, cross-linked acrylic and *** polymer can make the heat resistance increased to 125-150 degrees Celsius)

Plastic optical fiber in the attenuation and bandwidth of the latest practical advances in the following: Japan's ASAHI GLASS company said in July 2000, the company implemented Keio University's GI-POF technology commercialization of the use of perfluorinated polymers CYTOP Manufacturing GI fiber, named GI-GOF, trade name Lucina, attenuation rate of 3Gb / s, bandwidth greater than 200MHz.km.

Plastic optical fiber in the heat resistance of the latest practical progress: Japan's JSR and Asahi Kasei Co., Ltd. joint development of heat-resistant transparent resin ARTON (norbornene, icthyrene) manufactured SI-POF, heat resistant 170 degrees Celsius. Ltd. jointly developed a heat-resistant transparent resin ARTON (norbornene, icosahedral) manufacturing SI-POF, heat-resistant 170 degrees Celsius, is expected in the first half of 2001 can supply the automotive market.

Four, plastic optical fiber product development

1. fiber structure

Plastic optical fiber, as the name implies, that is, the core of the optical fiber and cladding are plastic materials. Compared with the large core diameter 50/125μm and 62.5/125μm quartz glass multimode fiber, the core diameter of the plastic fiber is up to 200-1000μm, and its splicing can be used without fiber positioning sleeve cheap injection molded plastic connectors, even if the fiber splicing in the core alignment produces a ± 30μm deviation will not affect the coupling loss. It is the plastic fiber structure gives it the advantages of fast construction and low cost of splicing. In addition, the core diameter of 100μm or larger can eliminate the intermodal noise in the quartz glass multimode fiber;

2. Fiber optic materials

Plastic fiber optic material selection, people should focus on solving the problem is the material's own attenuation should be low, dispersion should be small, the chemical stability should be good, simple to manufacture, inexpensive and so on.

Selected as plastic optical fiber core material: polymethyl methacrylate, polystyrene polycarbonate, fluorinated polymethyl methacrylate and perfluorocarbon resin, etc.; Selected as a plastic optical fiber cladding: polymethyl methacrylate, fluorine plastic, silicone resin, etc.. The reason is: these polymers ① with good light transmission, optical uniformity, refractive index adjustment convenience, etc.; ② to the monomer exists through the decompression distillation method can be purified; ③ the formation of optical fibers, the ability to strong; ④ processing and chemical stability and inexpensive, etc.;

3. Manufacturing process

Currently used in the industry to manufacture plastic optical fibers in the two methods: extrusion and interfacial gel method are evolved from the plastic production process. Plastic production process evolved.

The extrusion method is mainly used to manufacture plastic fibers with step refractive index distribution. The process steps are roughly as follows: first, as the core of the polymethyl methacrylate monomer methyl methacrylate purified by distillation under reduced pressure, together with the polymerization initiator and chain transfer agent

and sent to the polymerization container, and then put the container into an electric oven to heat, and placed for a certain period of time in order to make the monomer completely polymerization, and finally, the container containing completely polymerized polymethyl methacrylate heated to the Drawing temperature, and dry nitrogen from the upper end of the container has been melted polymer pressure, the bottom of the container small mouth will be extruded a plastic optical fiber core, at the same time so that the extrusion of the fiber core and then coated with a layer of low refractive index of the polymer, was made of step-type plastic optical fiber.

Gradient refractive index distribution of plastic optical fiber manufacturing method for the interface gel method, the interface gel method of the process steps are roughly as follows: first of all, the high refractive index dopant placed in the core monomer to make the core mixing solution, followed by the control of polymerization speed, polymer molecular weight size of the initiator and chain transfer agent into the core mixing solution, and then into the solution into a selection of cladding materials, poly(methylene propylene methyl ester) (PMMA) hollow tube. The solution is then put into a hollow tube selected as the cladding material, polymethyl methacrylate (PMMA), and finally the PMMA tube containing the core mix solution is put into an oven and polymerized at a certain temperature and under certain conditions. During the polymerization process, the PMMA tube is gradually swollen by the mixed solution, thus forming a gel phase on the inner wall of the PMMA tube. In the gel phase molecular motion slows down, the polymerization reaction due to the "gel effect" and accelerated, the thickness of the polymer gradually thickened, the polymerization terminated in the center of the PMMA tube, so as to obtain a refractive index along the radial gradient distribution of fiber optic pre-fabricated rods, and then finally the plastic optical fiber pre-fabricated rods into the heating furnace heating and pulling made of gradient refractive index Distribution of plastic optical fiber;

4. Fiber performance

Plastic optical fiber performance research focuses on attenuation, dispersion, thermal stability and so on.

(1) attenuation

Plastic fiber attenuation is mainly limited by the core cladding plastic material absorption loss and dispersion loss. People are through the selection of low refractive index and isothermal compression rate of small plastic materials and through the stabilization of plastic optical fiber manufacturing process to reduce structural defects (such as core diameter fluctuations, core cladding interfacial defects, etc.) to make the plastic optical fiber to obtain a small scattering loss, and the absorption loss of plastic materials is by the molecular bonding (hydrocarbon, fluorine, etc.) stretching and vibration absorption and electron jump absorption caused by.

In the carbon-hydrogen bond as the basic skeleton of plastic materials, in the wavelength of 650nm at the attenuation coefficient of about 120db/km, if the fluorine atoms to replace the carbon-hydrogen bond in the hydrogen composed of fluorinated plastic materials, not only the intrinsic attenuation of the small, but also reduces the dispersion. Fluorinated plastic made of gradient refractive index plastic optical fiber, no atomic vibration in the infrared region caused by absorption loss. Therefore, can be produced in the visible to infrared range of attenuation is very small, that is, in the 0.85 μm wavelength attenuation coefficient of 41db / km, in the 1.3 μm wavelength attenuation of 33db / km gradient refractive index distribution of plastic optical fiber.

(2) bandwidth

Plastic optical fiber used as a short-distance optical transmission medium, according to the shape of its refractive index distribution can be divided into two kinds: step refractive index distribution of plastic fibers and gradient refractive index distribution of plastic fibers. Step refractive index distribution plastic fiber due to the intermodal dispersion effect of incident light repeated reflection, the shot waveform relative to the incident waveform broadening, so its transmission bandwidth is only a few dozen to hundreds of MHz.km. Fluoride gradient refractive index distribution plastic optical fiber from the choice of low dispersion materials, and then optimize the gradient refractive index distribution means, can be its refractive index distribution index in 0.85-1.3 μm wavelength, and its refractive index distribution is 0.85-1.3 μm wavelength. -1.3μm wavelength range selected as 2.07-2.33, so as to suppress intermodal dispersion, control the effect of the incident light wave relative to the broadening of the incident light wave, and then can be produced transmission bandwidth up to a few hundred MHz.km to 10GHz.km gradient refractive index distribution of the plastic optical fiber.

(3) thermal stability

Because the plastic optical fiber is composed of plastic materials, so its work in the high temperature environment will occur oxidative degradation. Oxidative degradation is formed by carbonyl groups, double bonds and cross-links in the fiber core material. Oxidative degradation will promote the acceleration of the electron jump, which in turn causes the fiber loss to increase. In order to effectively improve the thermal stability of plastic optical fiber, the usual practice is: ① selection of plastic materials containing fluorine or silicon to manufacture plastic optical fibers; ② plastic optical fiber light source operating wavelength selected at greater than 660nm, in order to obtain the plastic optical fiber thermal stability of long-term reliability.

Five, the key to technology

The current key to the technology of plastic optical fiber products to address the issue of two: First, the design of new light-transmitting materials and cladding materials. Plastic optical fiber with quartz glass fiber from two parts: one for the core material, two for the skin. To create a high-quality optical fiber both are very important, the core of the fiber requires transparency and refractive index of the higher the better, while the skin is required to refractive index is less than the core, and the greater the difference between the two the better. But to improve the refractive index of the core material is more difficult, and reduce the refractive index of the skin layer has the potential to dig, mainly focused on fluoropolymers. The second point of attack is the process conditions, research on how to control the core material polymer molecular weight, uniformity and improve the transparency of the new fiber optic technology, to further improve the light transmission efficiency and reduce the optical loss rate. Once these two issues have been satisfactorily resolved, the plastic optical fiber will completely replace the quartz fiber.

In recent years, the Japanese company for the poor light transmission of plastic optical fiber analysis and improvement, they believe that the main reason lies in the resin within the hydrocarbon combination of absorption of near-infrared wavelengths. In response, Asahi Glass Manufacturing developed a perfluorinated resin material that does not absorb near-infrared wavelengths because it does not contain hydrogen. At the same time, because of its ring structure is amorphous, visible light transmittance has reached more than 95%.

The core wire on the inside of the fiber, the refractive index of light is high, while the metal cladding on the outside has a low refractive index. Therefore, the core line in the axis of the highest refractive index of light, to the surrounding gradually lower the slowly changing refractive index of the structure form. With this structure, the conveyor field can be expanded and information can be transmitted 200 to 500 meters at a speed of 1 gigabyte per second. Depending on the availability of samples, Asahi Glass Manufacturing will put this new type of optical fiber into mass production within a year or two. These newly developed plastic optical fibers improve the refractive index of the central portion of the signal to overcome the shortcomings of easy attenuation, the transmission capacity of each fiber can be up to 1 ~ 2.5 GB / s, while in the fiber connection, do not need to be accurately aligned with the position of the fiber, in this regard, better than glass optical fiber.

In terms of the capacity of plastic optical fiber, Japan's Mitsubishi Rayon company developed a high-capacity plastic optical fiber, it is possible to replace the quartz glass fiber. This plastic optical fiber raw material is very common, by a kind of invented in the 1960s called Polym-ethyl methacrylate synthetic resin made. Mitsubishi Rayon uses a decreasing from the center of the fiber to the edge of the gradient refraction technology, so that the signal can be a constant sinusoidal curve in the optical fiber through the effective transmission capacity is 30 times the ordinary plastic optical fiber. Compared with the diameter of 0.1-0.01mm glass fiber, this 1mm diameter plastic fiber cross-section, easier to connect, so the installation cost is only about 1/10 of the glass fiber, and ordinary copper cable almost. In the past, glass optical fiber to connect a need to spend 20,000 30,000 yen, while the new plastic fiber optic connection costs as little as 1 O yen, which can significantly save money. The source said, from the cost point of view, without this technology, the optical fiber to the home is not realized.

Six, development prospects

Plastic optical fiber as an ideal transmission medium for short-distance communication networks, in the future home intelligence, office automation, industrial control network. Vehicle-mounted airborne communication network, military communication network and multimedia equipment in the data transmission has an important position.

Through plastic optical fiber, we can achieve intelligent home appliances (home PC, HDTV, telephone, digital imaging equipment, home security equipment, air conditioning, refrigerators, audio systems, kitchen appliances, etc.) networking, to achieve home automation and remote control and management, and to improve the quality of life; through the plastic optical fiber, we can achieve the networking of office equipment, such as computer networking can be achieved computer Parallel processing, high-speed transmission of data between office equipment can greatly improve work efficiency, to achieve telecommuting and so on.

In the low-speed LAN data rate is less than 100Mbps, 100 meters within the range of transmission can be achieved with SI-type plastic optical fiber; 150Mbps 50 meters within the range of transmission can be achieved with a small numerical aperture POF.

POF can be widely used in the manufacturing industry. Through the converter, POF can be connected with RS232, RS422, 100Mbps Ethernet, token network and other standard protocol interfaces, thus providing stable and reliable communication lines in harsh industrial manufacturing environments. Capable of transmitting industrial control signals and commands at high speeds, it avoids the risk of communication transmission interruption due to electromagnetic interference caused by the use of metallic cable lines.

Lightweight and durable, POF can form a network of on-board machine communication networks and control systems, incorporating peripherals such as micro-computers, satellite navigation equipment, cell phones, faxes, etc. into the overall design of the locomotive, and travelers can also enjoy music, movies, video games, shopping, Internet and other services from their seats via the plastic fiber optic network.

In military communications, POF is being developed for high-speed transmission of a large number of third, classified information, such as the use of POF light weight, good flexibility, connectivity and fast, suitable for in the body with the characteristics of the lightweight computer system for soldiers to wear and be able to plug into the communications network to download, store, send, receive mission-critical information, and in the helmet display.

In summary, with the development of science and technology, the application of plastic optical fiber is more and more extensive, the development of its market will become more and more broad. Foreign applications in the development of plastic optical fiber has achieved greater results, and continue to increase the new application of research inputs, South Korea, China and Taiwan have been put into the R & D production of manufacturers, so the industry should be more on the research and development of plastic optical fiber to be closely watched.

This article from the "863 construction engineering information network" reproduced in the form of a link to indicate the source URL:/power/powerzmgc/200611/19477_4.html