According to the latest literature material and international technology exchange information review optical fiber preform bar manufacturing technology of the current status and development trend, the key is "two-step" processes, including various FRP rod manufacturing technology (OVD VAD, MCVD, PCVD, and outsourcing layer manufacturing technology (casing method, plasma spraying method, flame hydrolysis method, melt - sol-gel), hope to domestic fiber industry development wrbanization.

At present, which has great development of optical fiber &cable global climate, American KMI company good forecast, the next 10 years, global optical fiber &cable demand will continue to grow, to adapt to the fiber optic cable to increased demand, international each big fiber manufacturers are a new round of modification, at the same time, domestic fiber industry development momentum is also very strong, some fiber production enterprise is confirmed, will also new several large fiber factory. Here, the technical route choice is very important.

A prefabricated great ", manufacturing two-step "fiber industry in the 1970s rise.

For more than twenty years, optical fiber manufacturers process has been constantly development. Because of optical fiber preform bar manufacturing technology is the core of optical fiber manufacturing process, optical fiber industry with optical fiber preform has great manufacturing technology to naming fiber manufacturing process. According to the traditional naming methods, the current optical fiber technology market four craft coexist, namely OVD VAD, MCVD, PCVD,. However, only with the above process name simply says the current production process is not comprehensive. The current commercial production of optical fiber preform great steam deposition technology has developed for "two-step" (Processes) to - step. Figure 1 all-roundly describes the current commercial production of optical fiber Preform great technology, among them, OVD, MCVD process such as name said only production of step 1 prefabricated rods, i.e. production mandrel (Core - rod/Preform/Initial ask Preform) USES technology,

In production mandrel, not only to make when the core must also manufacturing sub-contract layer, this is to ensure the quality of the optical fiber, then, can put a mandrel pull into many small thin rods, also can not pull thin, it depends on the size of the rods. The second step, after a mandrel outsourcing layer (known as additional technical or Overcladding), outsourcing prefabricated stick, made before the drawing, prefabricated great pull thin can also don't pull a fine, it depends on the prefabricated rods and wiredrawing furnace size.

So, the so-called "two-step" is not limited to two step, optical fiber preform rods mainly depends on the optical properties of rods manufacturing technology; Optical fiber preform great cost depends mainly on outsourcing technology, therefore, FRP rod manufacturing technology and outsourcing technology will be fully explained the current optical characteristics of great manufacturing process gets. See figure 1.

Here to explain is:

The mandrel Washington figure 1 technical name and casing method, is already known, in addition, do not need to say.

SOOT "method, had" used "foreign literature in the process" to denote SOOT VAD OVD, sedimentary processes such as the flame hydrolysis. In this paper we call: SOOT outsourcing technology, instead of OVD terms, in solidarity with the difference between OVD mandrel technology, this technology in the United States and Japan each company has widely applied.

Washington - Plasma spraying (Spray), it is to point to by high-frequency Plasma flame will quartz powder made in mandrel melt on prefabricated great technology made great invention, use, the alcatel.

Second-ranking Sol sol-gel (Sol - - gel) used for outsourcing technology, is the United States invented, including two lucent's approach. First, use first sol -- gel synthetic quartz tube as legal into casing, reoccupy casing legal system into big precast stick; Secondly, use first sol -- gel legal synthetic quartz powder, and as with high frequency plasma flame will melt synthetic quartz powder made in mandrel made big on prefabricated great technology, so in essence, it belongs to the SOOT or plasma spraying method.

Second, mandrel development trend of manufacturing process

2.1 various chemical vapor deposition process from 1980 to 2000 years of development

MCVD is the earliest mature technics, early multimode fiber is mainly the process production, in the 1980s, with conventional single-mode optical fiber after the mature, SMF) (OVD, VAD in fiber market share is increasing rapidly, the United States and the Japanese companies are corning MCVD process, stop using the MCVD market share fell rapidly VAD process OVD, share increase quickly. But, MCVD process improvement, many new technologies into the, therefore hitherto, accounts for about one-third of the market share. Table 1 list four chemical vapor deposition process from 1980 to 2000 the change of market share. Table 1 various chemical vapor deposition process what hold market share (%) changes (1980-2000) note: all kinds of process described here are based on the share of the manufacturing process of rods to differentiate, do not consider its outsourcing process.

2.2 MCVD development

In the first MCVD is itself on a lathe were packet layer deposition, core deposition, weld shrink into, this is typical prefabricated stick "one-step". At present, alcatel has will melt shrink separate, deposition and the sedimentary later, with the other a special lathe melt shrink into stick, and graphite induction furnace instead of hydrogen flame do melt penetrating shrink into great heat.

Machine adopts large diameter synthetic quartz tube instead of natural crystal powder made of melting small diameter of quartz tube as underlay tube, currently in production of the substrate with synthetic quartz tube diameter 40mm, outside approximately 1.2 ~ 1.5 m sedimentary length. "

The most important is, itself with various outside deposition techniques replaced the casing method to make big, such as advance with great flame hydrolysis outsourcing and plasma outsourcing technology in producing outsourcing layer of rods, formed MCVD sedimentary process with the combination of hybrid technology. These new technologies make up the traditional MCVD process deposition rate is low, the poor quality of geometry size precision and reduce the cost, improve quality, and increase competitiveness.

Second-ranking development in low cost and high quality, large size casing manufacturing methods (such as sol-gel method of sol-gel, OVD - for casing use.)

VAD process development. 2.3

Second-ranking VAD process in the 1970s, core and packet layer and deposition, meanwhile, prefabricated continuous sintering boasts manufacturing process.

The 1980s VAD process itself is to make large diameter rods, then put the large diameter rods into many small fiber pull thin rods, reoccupy casing prefabricated stick, legal into from "one-step" into "ldpe-g-nvp".

Second-ranking with SOOT in the 1990s to replace casing legal outsourcing into optical fiber preform stick.

Since 1990s, using Washington VAD manufacturers increased, in addition to Japan TengCang ancient river, the outside, Hitachi, letter, mitsubishi, zhao and companies such as obtained from Japan NTT VAD craft production of optical fiber used the permission, and implement the redevelopment, realized commercialization VAD process, lucent also from sumitomo companies bought VAD technology license, use in the United States also and sumitomo VAD method was established, and the joint venture fiber factory opportunity VAD fiber production for many years, then observed, lucent will VAD technology to its Atlanta introduction optical fiber factory. The United States ENSIGN in the purchase of the SpecTran company BICKFORD company's assets - while, also won VAD process. And, incidentally, it is already in late 1999 the SpecTran company by American lucent through mergers and acquisitions.

The development of OVD process. 2.4

Second-ranking blowtorch deposition from single how gush machine and deposition, deposition rate doubled.

From a device a deposition took a stick to a device and sedimentary much stick.

Sedimentary cores, from Washington in coatings made great "continuous prefabricated one-step" into "ldpe-g-nvp"; Namely first use ceramic rod or graphite rods for target bar, only the core materials (including a few sedimentary) makes the packet level of large diameter mandrel by water, after the sintering of large diameter rods into many roots pull thin small diameter rods, reoccupy these small diameter rods for target sticks sedimentary packet layer, make optical fiber preform stick, greatly improved the productivity and reduce the cost.

The development of PCVD process. 2.5

As with MCVD itself, the current PCVD process also USES a large diameter synthetic quartz tube instead of natural crystal weld system the quartz tube as underlay tube.

Second-ranking POF company has developed the Netherlands PVCD craft, substrate fourteen from initial 16mm tube diameter in years, up to 60mm to raise deposition rate of 2 ~ 3g/min, sedimentary length 1.2 ~ 1.5 m.

Washington still is made with casing legal system, but a large precast rods of casing is weighed a few kilograms.

As MCVD in principle and the second-ranking PCVD, also can form with the combination of sedimentary processes, but so far the mixed process were reported.

2.6 various mandrel process compare

Various mandrel technology make the same kind of fiber optic products, there was a big difference between the productivity; Production of optical fiber will require certain varieties by the most suitable mandrel technology in the near future, given the international use most, SMF fiber is still. Therefore, figure 2 shows various process production SMF's latest economic analysis results. This compares the production 100 million km fiber all the equipment needed quantity; Among them MCVD need 6 ~ 12 units (sets); VAD need 4 ~ 6 sets); OVD needs 1 ~ 2 sets). Obviously, MCVD request more mechanical equipment investment. However, various equipment unit price is different, the price MCVD equipment with the lowest. So the difference, equipment, a total investment of the difference between the number of if the equipment is not so big.

2.7 summary

From table 1 shows, MCVD mandrel percent of the world market share of continuous reduction and the other three kinds of process is increases year by year. It is predicted that the next 10, multimode fiber (MMF) and the zero dispersion fiber (NZDSF) market share will continue to increase, SMF market share to drop, because MMF and the transmission properties of NZDSF of radial refractive index distribution (RIP) defects is very sensitive. In a mandrel manufacturing process to be precise control RIP, in this respect, MCVD, especially compared with OVD, PVCD VAD has obvious advantages. The expansion of the market NZDSF and MMF, mean more MCVD, PCVD process applications. OVD process with the American VAD process with the corning and several Japanese companies such as sumitomo, cane storehouse, ancient river, the letter the etc, in the 1980s had abandoned MCVD, according to reports, the current, may consider in its factory in MCVD or introduce PCVD hiring again.

Three, outsourcing technology development trend

3.1 various outsourcing technology from 1980 to 2000 years of development in the early 1980s, with internationally to greater casing legal MCVD and prefabricated stick, PCVD mandrel for, this is the most popular outsourcing methods adopted. Meanwhile, VAD process also USES a casing method, began the SMF, which marks the commercial production of prefabricated bar manufacturing process to "two-step" change, later, corning company will SOOT outsourcing technology used in industrial production, and then, with the manufacturer also VAD production of optical fiber with SOOT outsourcing technology instead of casing method, throughout the 1980s, casing method has been declining share of. In the 1990s, alcatel use plasma spraying technology replaced the casing law; Lucent company developed sol -- gel outsourcing technology, almost all VAD, OVD manufacturing fiber with rods manufacturers are using the SOOT outsourcing technology. These enable casing method share continue to fall. See table 2.

Casing method share the fundamental reason is: drop the price of synthetic quartz tube high. First, cost analysis shows that the casing method with other outsourcing if if the price of technical competition, the pipe down to 100 to $/ kg. It now appears that tube to the price is unlikely to reduce to this level. Therefore, with the method of precast great casing manufacturing factory will be fewer. Secondly, to do with the casing method, this requires large precast great big size, and thick wall bushing manufacture this specifications of the casing, and a high price is very difficult.

As fiber-optic prices continue to fall, fiber manufacturing costs will determine the success or failure of the height competition. And manufacture large precast stick is helpful for reducing fiber manufacturing cost (precast great cost, wiredrawing cost, testing cost will increase of prefabricated stick because of lower). Therefore, for optical maker survival, prefabricated great size increases increasingly critical, because to do big casing method, therefore, prefabricated bar before other since alcatel manufacturer will also give up microbent single-mode optical fiber casing method, and choose can high rate of prefabricated great production big more economic outsourcing technology. The vast majority of them will choose SOOT outsourcing, because of its equipment and technology existing goods

3.2 to all sorts of outsourcing of the technical analysis in 1985 after, casing method has been in decline; Has not been formed by sol-gel method climate. So, here basically on plasma method and SOOT method for analysis. These two kinds of methods such as the main difference is shown in table 3.

Second-ranking material: natural quartz powder, from quality crystal mineral, limited resources, (our current production of optical fiber and quartz tube used natural quartz powder still need to import); The purity of natural quartz powder is limited. And four chlorinated silicon is a byproduct of the semiconductor industry sources are rich; The production of SOOT is with synthetic quartz materials, high purity, be helpful for fiber strength and fatigue parameters. In this respect, SOOT process than plasma process.

Second-ranking process: SOOT process to produce hydrogen gas (such as the need to undertake handling), and, in order to improve the deposition rate and had to sacrifice deposition efficiency (far below 50 percent), in sintering with chlorine (virulent need (expensive) and ammonia, these pcis) reduce costs. And plasma technology without the above-mentioned problems, deposition is transparent after prefabricated bar, in this respect, plasma technology better than SOOT process.

Heat aspects: plasma technology itself is more complicated, and hydrogen, oxygen flares in natural gas, technical simple, fare is very low. In this respect, SOOT process than plasma process. 3.3 summary from table 2 visible, 1985, casing method after one-fifth of the world market share of SOOT process, continuous reduction is increases year by year.

At present, various process of the world market share for: casing SOOT62 %, 28%, method of plasma 8%, sol-gel 2%. Casing the main limiting factor is method of synthetic quartz tube prices high. In fact, the method of using the casing a few companies have said, if can get large size casing, they will create greater precast stick. As long as synthetic quartz tube price drop too low enough, this kind of method is the most simple and most practical. Alcatel plasma spraying technology mainly limiting factor is the natural quartz powder natural resources are limited.

Sol-gel is developing, sol-gel synthetic quartz powder and the combination of plasma spraying, may be very good technology, this depends on the input of development efforts.

SOOT process have accounted for absolute superiority. Because of its equipment and technology, its applications will have goods more widely. For OVD or VAD already owned by the manufacturer, SOOT outsourcing process is very convenient; For MCVD or PCVD manufacturers only is required to buy equipment and technology lager sum.

Four, optical fiber cost comparison

4.1 precast great technology and optical fiber cost OVD mandrel according to think, with SOOT outsourcing of prefabricated great technology lowest cost. According to estimates, its production cost about 15 $/ km. VAD mandrel SOOT outsourcing production costs add OVD mandrel than SOOT outsourcing with 25% higher; MCVD plus the cost of production casing method than OVD mandrel SOOT outsourcing with 40% higher. Three kinds of precast great process cost comparison, see table 4.

4.2 production scale and optical fiber optical fiber factory assuming the cost by the same level of technology, use with SOOT VAD mandrel outsource production, the different production capacity SMF or scale of production cost impact of fig.03 shows. Levin show that mass production has the quite big cost advantage. As fiber-optic down prices and productivity enhancement, feasible minimum economic production scale will be increased, from past thought 5O million km fiber production increased to 100 million km.

In addition, the above analysis of a single technology, only a single product, if compare with various techniques considering producing a variety of products, most people believe that, in this case, large manufacturers still favor.

Five, the summary

The current commercial production of optical fiber preform great steam deposition technology has developed for including mandrel manufacturing and outsourcing technology "two-step", production routine single-mode optical fiber, with OVD mandrel SOOT outsourcing with lowest cost of prefabricated great technology, the expansion of the market NZDSF and MMF, will mean more use of MCVD, PCVD process. Various mandrel process all need to choose appropriate outsourcing technology instead of casing method, the vast majority of them will choose SOOT outsourcing, because of its equipment and technology existing goods, in addition to the selection process, the scale of production for optical fiber outside the cost, mass production have obvious influence with considerable cost advantage.

Above conclusion is not absolute, even the same process, the same scale, production the same product in different countries, regions, the company's effect also never be the same, because, raw material sources, by-products can comprehensive utilization and management system, specific factors also needed to consider. In addition, in order to strengthen the competitiveness of the enterprises, and shall have suited to production various products of multiple techniques.