CN201247332Y - Single mode optical fiber for LAN and access network - Google Patents

Abstract

The utility model discloses single mode fiber which is used in a local area network and an access network, wherein the single mode fiber is composed of naked glass fiber whose cross section is round and two resin protective layers which are enclosed on the periphery of the naked glass fiber and whose cross sections are in circular ring shapes. The single mode fiber is characterized in that the naked glass fiber is composed of a core layer whose cross section is in a round shape and two cladding layers whose cross sections are in circular ring shapes, the refractive index of the core layer is higher than the refractive index of the two cladding layers, the refractive index difference of the core layer and the first cladding layer is bigger than the refractive index difference of the first cladding layer and the second cladding layer, the second cladding layer is composed of pure SiO2, the profiles of the refractive index of the core layer are distributed in power functions, and the profiles of the two cladding layers are distributed in a step shape. The loss of the fiber is not sensitive to fiber bending and respectively satisfies the demands of ITU.TG.657.A and G.657.B fiber standards. The single mode fiber is applicable to the local area network and the access network of fiber to the home (FTTH) and the like.

Description

The single-mode fiber that a kind of LAN (Local Area Network) and Access Network are used

Technical field

The utility model relates to a kind of optical fiber, particularly satisfy the ITU.TG.657 sonet standard, bending loss is insensitive, the single-mode fiber of the LAN (Local Area Network) such as (FTTH) that is applicable to that Fiber to the home and access net system.

Background technology

Along with broadband services is extended to family, and even the construction emphasis of Communication ray network by core net to fiber optic local area network, Access Network Fiber to the home (FTTH) development.FTTH is subjected to the influence (mostly being street, building, turning etc.) of complicated applications occasion as the final stage distance that inserts, and access point is many, and influences such as outstanding during because of wiring draws, bending factor, and optical fiber exists crooked phenomenon a lot.This bending property to optical fiber is had higher requirement.The conventional G.652 mode field diameter of optical fiber is about 9.2 μ m, owing to be subjected to the influence of bending loss and mechanical stress, generally require fiber bending radius not to be difficult to tie up the same tuftlet of imaging power lead along the wall wiring and with excess fiber length in the use less than 30mm indoor.The universal needs of FTTH further improve the operating performance of optical fiber, and make the miniaturization of indoor set and terminal box become possibility, so bend-insensitive optical fiber will become the emphasis of following fiber optic applications.

International Telecommunication Union has formally put into effect specification and standard about the bend-insensitive optical fiber cable in Dec, 2006, and this type of optical fiber cable is defined as G.657 optical fiber cable.G.657 the optical fiber cable key property is exactly to allow that littler bending diameter and bending loss are lower, can better satisfy the construction requirement of FTTH engineering.Compare with the single-mode fiber (C-SMF) of routine, G.657 optical fiber has better bending resistance, makes it be applicable to Optical Access Network, comprises the various wirings of the buildings that is positioned at the Optical Access Network terminal.G.657A and G.657B according to operation wavelength and usable range, G.657 optical fiber can be divided into two classes:.G.657A characteristics are to improve the bending loss characteristic of optical fiber under the prerequisite of comprehensive satisfied G.652.D standard.G.657.A can be in the whole operating wavelength range work of 1260～1625nm.G.657.A optical fiber can be used as a subclass G.652.D, and its transmission and interconnection performance are with G.652D identical, but G.657.A optical fiber has better bending property and more accurate physical dimension technical requirement.G.657.B characteristics are to improve the bending loss characteristic of optical fiber more fully, needn't necessarily satisfy G.652.D standard, and main consideration is used in interior of building.G.657.B the transmission operation wavelength of optical fiber is respectively 1310nm, 1550nm and 1625nm.Because lower mode field diameter, G.657.B also with G.652 optical fiber is different with connection performance in the welding of optical fiber, but can be under the very little situation of bending radius operate as normal.

In fact, bending resistance damage (the curved damage is the abbreviation of bending loss) optical fiber is exactly one of important content of fiber optic materials R and D always.As far back as eighties of last century eighties, the AT﹠amp of the U.S.; The NTT company of T and Japan has just released respectively and has forced down covering and convex index fiber, and what this optical fiber was worked under 1.3 mum wavelengths can accomplish 1.35 μ m by wavelength.By the effort of decades, optical fiber is decreased in the bending resistance that all released one after another of existing now many companies, and its anti-bending strength has also obtained very big improvement.For example, rattan storehouse company

With

Optical fiber is decreased in bending resistance, and it corresponds respectively to ITU-T G.652.B optical fiber and ITU-TG.652.D optical fiber, and the minimum of these optical fiber allows bending radius to reach 15mm, with respect to the bending radius of the 30mm of general single mode fiber, has dwindled half.The minimum of the PureAccess-Ultra optical fiber that Sumitomo Electric Industries release allows bending radius to be reduced to 7.5mm from the 30mm of routine.Optical fiber is decreased in the bending resistance of Corning Incorporated, and when bending radius was 32mm, its loss under 1550nm was no more than 1dB, corresponding by wavelength between 870nm～970nm.The bend insensitive optical fiber of flames of war (Bend Insensitive Fiber) 10mm, 30 the circle crooked situations under, its loss under 1550nm is not more than 0.5dB, and accordingly by wavelength below 1290nm.

Improving the bending property of optical fiber can set about from the structure of improving optical fiber.Help bend-insensitive optical fiber (Chinese patent application number: 200580022430.2 as the hole of Teng Cang, publication number is CN1981223A), this optical fiber is that bending loss under 5mm, the 1550nm wavelength is the 0.012dB/ circle in bending radius, mode field diameter (1550nm) is 7.8 μ m, and cutoff wavelength is 1.28 μ m.Though this fibre-optic mode field diameter is slightly less than C-SMF, but make the hole help optical fiber and C-SMF cross section to be complementary by electric arc, make average splice loss, splice attenuation reach 0.05dB, its fade performance also reaches the level of C-SMF, and 1.30 μ m and 1.55 μ m decay to 0.50dB/km and 0.28dB/km.The optical fiber that a kind of airport helps has also been introduced in China's patented claim (application number 200610119574.6, publication number are CN1971323A).The ditch of moral clarke helps BendBright ^XSG.657.A optical fiber, this optical fiber had not only met standard (with G.652.D compatible fully) but also had met G.657.B standard (curved decrease littler), and minimum bending radius is positioned at 1～10mm interval, and were lower than 0.05dB when the average splice loss, splice attenuation that adopts suitable procedure and C-SMF.It is a kind of based on nanoStructures that U.S. CORNING is released ^TMNovel bend-insensitive optical fiber--the ClearCurve of technology ^TMOptical fiber, this optical fiber are not only with G.652.D compatible fully, and G.657.B bending resistance compares, and setting exceeds 10 times.European patent application (application number: 89104889.4, publication number is: 0334247A2) proposed a kind of optical fiber of step change type refractive index profile of covering depression, the mode field diameter of this optical fiber is respectively about 6 μ m and 8 μ m.International patent application no is that PCT/US2006/035894, publication number are the insensitive optical fiber of bending loss that WO2007/040947 A1 has then proposed a kind of parabolic type index distribution.Application number be US2008/0056654 A1 United States Patent (USP) then utility model a kind of triple clad and second covering the insensitive optical fiber of bending loss with index distribution of certain depression.Application number is 200610051922.0, publication number be C 1971321A China's patented claim then utility model the bending resistance of a kind of ultra-fine low water peak decrease optical fiber.

Improving the bending property of optical fiber can also set about from the performance of the application of resin layer that improves optical fiber.As application number is that 03124078.x, publication number are that China's patented claim of CN1542473A has proposed a kind of optical fiber with high bending modulus of special resin layer, the and for example ColorLock of De Lake ^TMCoating process also strengthened the microbend performance and the reliability of optical fiber.

In the above-mentioned various prior aries of mentioning, by the structure of improving optical fiber, the refractive index profile of optical fiber, the different modes such as application of resin layer of optical fiber the bending property of optical fiber is improved respectively, but wherein much all be difficult to satisfy the requirement of the transmission performance of ITU.TG.657 regulation, some optical fiber that can satisfy transmission requirement is the structure relative complex then, and the technology difficulty of realization is big, manufacturing cost is high.Problem to be solved in the utility model is, seeks that a kind of structure is simple relatively, technology is relatively easy, can satisfy the novel bend-insensitive single-mode optical fiber of the G.657 serial sonet standard that international ITU.T tissue proposes simultaneously again.

The technical assignment of the technical problems to be solved in the utility model and proposition is that to overcome the loss of the optical fiber that prior art exists responsive to the bend ratio of optical fiber, can not satisfy contradiction such as the construction requirement of the complexity of FTTH LAN (Local Area Network), by particular design to optical fiber structure, provide a kind of simple in structure, make easily, the loss of optical fiber is to its bend-insensitive, and the I of the permission bending radius of optical fiber reaches 7.5mm, satisfies that ITU.TG657 series requires, as to can be used for LAN (Local Area Network) and Access Network transmission single-mode fiber.For this reason, main contents of the present utility model and technical scheme are as follows:

The single-mode fiber that a kind of LAN (Local Area Network) and Access Network are used; by xsect is that circular naked glass optical fiber and the resin protective layer that is enclosed in two annulars of this naked glass optical fiber periphery constitute; it is characterized in that described naked glass optical fiber is made up of a sandwich layer and two coverings; the refractive index of described sandwich layer is higher than the refractive index of two coverings; and the refringence of the described sandwich layer and first covering is greater than the refringence of first covering and second covering, and second covering is pure SiO ₂Form, the refractive index profile of sandwich layer is specific power function and distributes, and the refractive index profile of two coverings all is ladder pattern distribution.

As the further of technique scheme improved and replenish, the utility model also comprises following additional technical feature:

The refringence of the described sandwich layer and first covering is between 0.0033～0.0072; The refringence of first covering and second covering is between-0.0016～0; The thickness of sandwich layer is between 2.7～4.1 μ m; First cladding thickness is between 0.5～2.3 μ m; The thickness of second covering is between 56.7～59.8 μ m.

Perhaps, the refringence (Δ of the described sandwich layer and first covering ₁) between 0.0034～0.0045; Refringence (the Δ of first covering and second covering ₂) between-0.0006～0; The thickness of sandwich layer is between 3.5～4.0 μ m; The thickness of first covering is between 0.5～1.9 μ m; The thickness of second covering is between 56.6～58.5 μ m.At this moment, finished product optical fiber in the mode field diameter under the 1310nm wavelength (MFD) between 8.6 ± 0.4 μ m, its cutoff wavelength (λ _c) between 1180～1330nm; Loose when 10 circles are measured with 15mm half, the macrobending loss＜0.25dB of finished product optical fiber under the 1550nm wavelength, the macrobending loss＜1.0dB under the 1625nm wavelength; Loose when 1 circle is measured with 10mm half, the macrobending loss＜0.75dB of finished product optical fiber under the 1550nm wavelength, the macrobending loss＜1.5dB under the 1625nm wavelength.

Perhaps, the refringence (Δ of the described sandwich layer and first covering ₁) between 0.0058～0.0072; Refringence (the Δ of first covering and second covering ₂) between-0.0016～-0.0008; The thickness of sandwich layer is between 2.8～3.2 μ m; The thickness of first covering is between 0.8～2.1 μ m; The thickness of second covering is between 57.1～58.9 μ m.At this moment, finished product optical fiber in the mode field diameter under the 1310nm wavelength (MFD) between 6.5 ± 0.5 μ m, its cutoff wavelength (λ _c) between 1180～1330nm; Loose when 10 circles are measured with 15mm half, the macrobending loss＜0.03dB of finished product optical fiber under the 1550nm wavelength, the macrobending loss＜0.1dB under the 1625nm wavelength; Loose when 1 circle is measured with 10mm half, the macrobending loss＜0.1dB of finished product optical fiber under the 1550nm wavelength, the macrobending loss＜0.2dB under the 1625nm wavelength; Loose when 1 circle is measured with 7.5mm half, the macrobending loss＜0.5dB of finished product optical fiber under the 1550nm wavelength, the macrobending loss＜1.0dB under the 1625nm wavelength.

The diameter of described naked glass optical fiber is between 124.3～125.7 μ m; The thickness of first resin protective layer is 38 ± 1 μ m, and Young modulus is 1.1 ± 0.1MPa, and elastic modulus is 1.6 ± 0.1MPa; Thickness 22 ± 1 μ m of second resin protective layer (13), Young modulus is 700 ± 50MPa, elastic modulus is 1200 ± 100MPa; The diameter of finished product optical fiber is 242 ± 7 μ m.

The power exponent of the distribution power function of the close subregional refractive index profile of central part of described sandwich layer is between 3～5, and the power exponent of the distribution power function of the close subregional refractive index profile of first cladding part is between-9～-8.

Single-mode fiber of the present utility model can by the quartz glass that mixes constitute naked glass optical fiber sandwich layer, constitute the covering of naked glass optical fiber and the inside and outside two layers of resin protective seam that constitutes by resin by quartz glass, wherein the sandwich layer of naked glass optical fiber has particular structure with covering: the sandwich layer of optical fiber be doped with Ge or P or other chemical element that can increase refractive index, the relative higher zone of refractive index; First covering is pure SiO ₂Layer or doped F or S or other can reduce the zone of the chemical element of refractive index; Second covering is that the surrounding layer of optical fiber is pure SiO ₂Layer.The external diameter of naked glass optical fiber is 125 ± 1 μ m (summation of sandwich layer, first covering, second covering promptly is naked glass optical fiber external diameter, guarantees that by adjusting second covering three layers of summation also are the size of naked glass optical fiber in the manufacturing).The diameter of finished product optical fiber is 242 ± 7 μ m.

When making this optical fiber, earlier according to the refractive index profile that designs, it is the refractive index of sandwich layer, thickness, the refractive index of first covering, thickness, the parameters such as thickness of second covering, determine the component of each layer doping, again respectively with vapour deposition process (MCVD) (or Plasma Enhanced Chemical Vapor Deposition (PECVD) PCVD, or outside vapour deposition process OVD, or vertical vapour deposition process VAD etc.) makes the plug of the preform that adheres to specification, with outside vapour deposition (OVD) (or above-mentioned VAD, or above-mentioned MCVD, or above-mentioned PCVD, or method such as tiretube process RIC) thus making two coverings that are enclosed in the plug periphery obtains preform, on wire-drawer-tower this preform is drawn into naked glass optical fiber more at last, this naked glass optical fiber applies two coverings that form design size through twice UV-cured resin; , a series of machinery, optics and chemistry become the single-mode fiber finished product after screening the back reel.

The beneficial effects of the utility model are reasonably to design by sandwich layer and covering to naked glass optical fiber, realized feasible on technology, manufacturing tolerance require comparatively loose, manufacturing cost is comparatively cheap and it is current about sonet standard G.657 and be applicable to LAN (Local Area Network) and a kind of LAN (Local Area Network) of Access Network and the single-mode fiber that Access Network is used such as FTTH etc. to satisfy fully.

Along with the further popularization of optical fiber communication business, the enforcement of engineerings such as (FTTH) that particularly Fiber to the home, the bending resistance of optical fiber has obtained attention more and more widely, and it is one of important indicator of current and following investigation optical fiber property.Improving the bending property of optical fiber can set about from structure, composition and the application of resin layer of optical fiber, the utility model is from the structure of optical fiber and form two aspects the sandwich layer of optical fiber has been carried out critical design, make the sandwich layer of optical fiber be the power function distribution, and at first covering introducing index dip (Δ to a certain degree ₂Between-0.0016～0), thus the susceptibility of optical fiber of the present utility model reduced to fibre-optical bending, obtained excellent bend-insensitive performance.

Known studies show that, is that macrobending loss or microbending loss all increase along with the increase of optical fiber MAC value.The MAC value is mode field diameter (MFD) and cutoff wavelength (λ _c) ratio, it defines as the formula (1):

MAC＝MFD/λ _c (1)

In view of the above, by to the size of naked glass optical fiber sandwich layer, covering and the particular design of index distribution, reduced the MFD of optical fiber and increased the λ of optical fiber in the utility model _cThereby, realized the raising of the counter-bending drain performance of optical fiber.

Optical fiber of the present utility model has unique refractive index profile, waveguide performance and bend-insensitive performance: the MAC value is no more than 7.5; Zero-dispersion wavelength is between 1180～1330nm, and zero-dispersion slop is not more than 0.092ps/ (nm ²Km), by wavelength between 1200～1400nm.Compare with optical fiber G.652, its susceptibility to the bending of optical fiber reduces greatly, the permission bending radius of optical fiber can be reduced to 10mm by 30mm, even 7.5mm, thereby has reduced the difficulty and the cost of LAN (Local Area Network) and Access Network construction.

Description of drawings

Figure 1A and 1B are respectively the cross sectional representation of single-mode fiber of the present utility model (10) and the cross sectional representation of naked glass optical fiber (11).

Fig. 2 is the refractive index profile structural representation of naked glass optical fiber (11) among Fig. 1.

Fig. 3 is another synoptic diagram of naked glass optical fiber (11) refractive index profile structure among Fig. 1.

Figure 4 shows that the relation curve between the utility model fiber core layer thickness (a) and the fibre-optic mode field diameter (MFD).

Figure 5 shows that the utility model fiber core layer thickness (a) and optical fiber are by wavelength (λ _c) between relation curve.

Figure 6 shows that the relation curve between the utility model fiber core layer thickness (a) and the optical fiber MAC value.

Figure 7 shows that the utility model fiber core layer refringence (Δ ₁) and fibre-optic mode field diameter (MFD) between relation curve.

Figure 8 shows that the utility model fiber core layer refringence (Δ ₁) with optical fiber by wavelength (λ _c) between relation curve.

Figure 9 shows that the utility model fiber core layer refringence (Δ ₁) and optical fiber MAC value between relation curve.

Figure 10 shows that the poor (Δ of the utility model optical fiber first cladding index ₂) and fibre-optic mode field diameter (MFD) between relation curve.

Figure 11 shows that the poor (Δ of the utility model optical fiber first cladding index ₂) with optical fiber by wavelength (λ _c) between relation curve.

Figure 12 shows that the poor (Δ of the utility model optical fiber first cladding index ₂) and optical fiber MAC value between relation curve.

Figure 13 shows that the relation curve between the utility model optical fiber first cladding thickness (b) and the fibre-optic mode field diameter (MFD).

Figure 14 shows that the utility model optical fiber first cladding thickness (b) and the optical fiber relation curve between wavelength (λ c).

Figure 15 shows that the relation curve between the utility model optical fiber first cladding thickness (b) and the optical fiber MAC value.

Figure 16 shows that with 10mm half pine when 1 circle is measured the utility model optical fiber MAC value and the relation curve of optical fiber between the bending loss under the 1550nm wavelength.

Embodiment

With reference to Figure 1A, single-mode fiber is that finished product optical fiber is defined as 10.Its structure comprises: the xsect that is distributed in single-mode fiber 10 centers is circular naked glass optical fiber 11; and the xsect that is enclosed in single-mode fiber 11 peripheries successively is first resin protective layer 12 and second resin protective layer 13 of annular; this two resin protective layer is the polyacrylic resin material, can solidify by ultraviolet curing or other method to make.With reference to Figure 1B, naked glass optical fiber 11 comprise first covering 112 of the index dip that xsect is circular sandwich layer 111, xsect is annular and xsect be annular by pure SiO ₂Second covering, 113, the second coverings of forming 113 also can be described as surrounding layer.

The utility model can adopt gas phase axis depositing operation (VAD) (also available PCVD, OVD, MCVD or other similar approach replace) to prepare the plug of the preform with refractive index profile structure shown in Figure 2, and then makes pure SiO with OVD (also available PCVD, VAD, MCVD or other similar approach replace) technology ₂Surrounding layer, or adopt the RIC technology to wrap surrounding layer, thereby prepare preform at the plug periphery.Concrete technology is as described below:

Utilize VAD (or PCVD, MCVD, OVD etc.) to make preform: in plug manufacturing process such as VAD, by SiCl at blowtorch in conjunction with the method for OVD (or PCVD, MCVD, OVD etc.) ₄Doped with Ge Cl in the raw material ₄Refractive indices with suitable raising sandwich layer 111 ₁, and (be specially thickness a) by the sedimentary deposit size of parameters such as sedimentation time and material flow control sandwich layer 111; Doping by adjusting S (or F etc.) is to adjust the refractive indices of first covering 112 ₂Size, and control the sedimentary deposit size (being specially thickness b) of first covering 112 by parameters such as sedimentation time and material flows; Stop GeCl ₄Feed is with pure SiCl ₄For raw material continues spraying to make the segment thickness of second covering 113 to sedimentary deposit, and control the sedimentary deposit size of first covering 113 by parameters such as sedimentation time and material flows, in this step deposition, second covering, 113 thickness are not less than a and b sum 4.5 times, to prepare plug.Then, calculate according to the size of above-mentioned gained plug and the thickness of optical fiber triple clad 113 another part adopt cladding techniques such as OVD again, with SiCl ₄For raw material deposits one deck SiO in the plug periphery ₂Dust sinters transparent vitreum into through the vitrifacation stove, promptly obtains preform.

Adopt VAD (or PCVD, MCVD, OVD etc.) to be: to calculate the size of required plug according to the size of selecting sleeve pipe for use, and calculate physical dimension and the refractive index that each layer in the rate cross-section structure penetrated in the knockout packing in conjunction with the technology of RIC manufactured preform; Adopt identical method manufacturing plugs such as above-mentioned VAD; Adopt the RIC technology, the inside surface of the outside surface of plug and the sleeve pipe hydrofluorite (or other alternative chemical reagent) with finite concentration (as 35%) is cleaned up; Again plug one end is processed 2～4 air slots and plug is inserted in the outer tube match on cutting machine; The two ends that will have a sleeve pipe of plug connect quartzy ending pipe, are placed on MCVD or the PCVD lathe heating then and sleeve pipe are retracted to form preform on the plug.Make the space between sleeve pipe and the core bag keep negative pressure in the contraction process, the air of inside is discharged with the air slot of plug one end during contraction.

The preform that above-mentioned different process is prepared carries out spinning on spinning-drawing machine, the polyacrylic resin of while applied in two coats different hardness forms first resin protective layer 12 and second resin protective layer 13 promptly gets single-mode fiber 10.

With reference to Fig. 1, in the utility model, have the G.657 optical fiber of this kind structure, require sandwich layer 111 refractive indices ₁Between 0.0033～0.0072, permissible error is ± 2.3%; The thickness a of sandwich layer 111 is between 2.7～4.1 μ m, and permissible error is ± 3.3%.First covering, 112 refractive indices ₂Between-0.0016～0, permissible error is ± 2.0%; The thickness b of first covering 112 is between 0.5～2.3 μ m, and permissible error is ± 2.0%.Second covering 113 is pure SiO ₂Layer, its refringence is 0; The second cladding thickness c is between 56.7～59.8 μ m, and permissible error is ± 0.8%.The thickness c of second covering 113 can suitably revise by measures such as polishings after the prefabricated rods manufacturing is finished, and therefore the qualification rate of product is not had too big influence.The diameter of naked glass optical fiber 11 between 124.0～126.0 μ m, the about 38 μ m of the thickness of first resin protective layer 12, Young modulus is 1.1MPa, elastic modulus is 1.6MPa; The about 22 μ m of the thickness of second resin protective layer 13, Young modulus is 700MPa, elastic modulus is 1200MPa; The diameter of finished product optical fiber is controlled at 242 ± 7 μ m.Sandwich layer 111 refractive indices ₁, first covering, 112 refractive indices ₂Calculate with following formula respectively:

${\mathrm{\&Delta;}}_1=\frac{n1-n2}{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="Y200820162982E00171.png"\; state="\{\{state\}\}">n</figure-callout>}1}\&times;100\%---\left(2\right)$

${\mathrm{\&Delta;}}_2=\frac{n2-n0}{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="Y200820162982E00211.png,Y200820162982E00221.png"\; state="\{\{state\}\}">n</figure-callout>}2}\&times;100\%---\left(3\right)$

N0 is pure SiO in the formula ₂Refractive index, n1 is the refractive index of sandwich layer, n2 is the refractive index of first covering.

With reference to Fig. 2 and Fig. 3, single-mode fiber of the present utility model has unique refractive index profile structure.The refractive index profile of sandwich layer 111 is power function and distributes, and the power exponent of the distribution function of the refractive index profile of close fiber optic hub subregion is between 3～5, and the power exponent of the distribution function of the close subregional refractive index profile of first cladding part is between-9～-8.First covering 112 can have certain index dip or not have index dip (described index dip is reflected on the refractive index profile as being the shaped form shape that is in depression among Fig. 2), is ladder pattern distribution when index dip.Second covering 113 is ladder pattern distribution.

The structure of above-mentioned optical fiber and the relation curve of performance such as Fig. 4～shown in Figure 16.

Curve shown in Figure 4 is irregular curve shape, and demonstrate the utility model Mode-field Diameter in Single-mode (MFD) and increase to present to increase afterwards earlier with fiber core layer thickness a and reduce, and then the variation tendency of increase.

Curve shown in Figure 5 is the curve shape that approximate power function distributes, and demonstrates the cutoff wavelength λ of the utility model single-mode fiber _cIncrease with fiber core layer thickness a demonstrates ever-increasing variation relation.

Curve shown in Figure 6 is approximate parabolical curve shape, and the MAC value that demonstrates the utility model single-mode fiber increases earlier the variation relation that afterwards reduces with the increase of fiber core layer thickness a.

Curve shown in Figure 7 is the curve shape that approximate logarithmic function distributes, and demonstrates the utility model Mode-field Diameter in Single-mode MFD with the fiber core layer refractive indices ₁Increase and ever-reduced variation relation.

Curve shown in Figure 8 is the shape of near linear, demonstrates the cutoff wavelength λ of the utility model single-mode fiber _cWith the fiber core layer refractive indices ₁Increase and the variation relation that constantly increases.

Curve shown in Figure 9 is the curve shape that approximate logarithmic function distributes, and demonstrates the utility model single-mode fiber MAC value with the fiber core layer refractive indices ₁Increase and ever-reduced variation relation.

Curve shown in Figure 10 is irregular curve shape, and the mode field diameter MFD that demonstrates the utility model single-mode fiber is with the optical fiber first cladding index difference Δ ₂Increase and the variation relation that constantly increases.

Curve shown in Figure 11 is irregular pattern curve, demonstrates the cutoff wavelength λ of the utility model single-mode fiber _cWith the optical fiber first cladding index difference Δ ₂Increase and the variation relation that reduces and is worked as Δ ₂The＜the-0.001st, this variation relation is linear substantially.

Curve shown in Figure 12 is the curve shape that approximate power function distributes, and demonstrates the utility model single-mode fiber MAC value with the optical fiber first cladding index difference Δ ₂Increase and the variation relation that constantly increases.

Curve shown in Figure 13 is the shape of near linear, demonstrates the fine mode field diameter MFD of the utility model light single mode and presents ever-reduced variation tendency with the increase of the optical fiber first cladding thickness b.

Curve shown in Figure 14 is the shape of nearly straight line, demonstrates the cutoff wavelength λ of the utility model optical fiber _cThe ever-increasing variation relation with the increase of the optical fiber first cladding thickness b.

Curve shown in Figure 15 is the shape of near linear, and the MAC value that demonstrates the utility model single-mode fiber is ever-reduced variation relation with the increase of the optical fiber first cladding thickness b.

Distribution plan shown in Figure 16 is the trend of continuous rising, and the bending loss that demonstrates the utility model single-mode fiber increases and the continuous variation relation that increases with MAC.

Embodiment 1:

Adopt the VAD technology to make plug, OVD (or RIC) technology is made the technology of surrounding layer and is made preform.When deposition sandwich layer 111, at raw material SiCl ₄The middle fixed GeCl of an amount that mixes ₄Make the sandwich layer refractive indices ₁Value under the 632.8nm wavelength is 0.0038; When deposition first covering 112 and part second covering 113, use pure SiCl ₄Raw material.By control blowtorch flow and sedimentation time each layer thickness is controlled to be: sandwich layer 111 thickness are 3.72 μ m; First covering, 112 layer thicknesses are 1.10 μ m; Second covering, 113 layer thicknesses are at 57.76 μ m.By control drawing speed, water dropper temperature etc. naked glass optical fiber diameter is controlled at 125.15 μ m; The thickness of first resin protective layer 12 and second resin protective layer, 13 coated with resins is respectively 37.4 μ m and 21.8 μ m; The final finished fibre diameter is 243.55 μ m; Control by resin and condition of cure makes the Young modulus of the win resin protective layer 12 and second resin protective layer 13 be about 1.1MPa and 1.2MPa respectively, and elastic modulus is respectively 760MPa and 1200MPa.Each performance parameter of present embodiment optical fiber is as follows: zero-dispersion wavelength λ ₀Be 1.313 μ m; By wavelength X _cBe 1.228 μ m; In the chromatic dispersion gradient coefficient S ₀Be 0.0878ps/nm ²/ km; Mode field diameter under the 1310nm wavelength is 8.55 μ m; In the wavelength coverage of 1288nm～1339nm, the maximum value 2.29ps/nm/km of abbe number; In the wavelength coverage of 1271nm～1360nm, the maximum value 3.89ps/nm/km of abbe number; It is 6.96 that characteristic parameter MAC value is decreased in bending resistance under 1310nm; Loose when 10 circles are measured with 15mm half, the macrobending loss 0.08dB under the 1550nm wavelength, the loss 0.017dB under the 1625nm wavelength; Loose when 1 circle is measured with 10mm half, the macrobending loss＜0.021dB under the 1550nm wavelength, the loss 0.05dB under the 1625nm wavelength.Present embodiment optical fiber meets ITU.T sonet standard G.657.A, and the mode field diameter of this optical fiber is suitable with G.652 serial optical fiber, can be well compatible with existing transmission network, can be used for the transmission system of LAN (Local Area Network) such as Fiber to the home.

Embodiment 2

Adopt the VAD technology to make plug, OVD (or RIC) technology is made the technology of surrounding layer and is made preform.When deposition sandwich layer 111, at raw material SiCl ₄The middle fixed GeCl of an amount that mixes ₄Make the sandwich layer refractive indices _IValue under the 632.8nm wavelength is 0.0065; When deposition first covering 112, at raw material SiCl ₄The middle fixed CF of an amount that mixes ₄Make 112 layers of refractive indices ₂Value under the 632.8nm wavelength is-0.0009; When deposition part second covering 113, use pure SiCl ₄Raw material.By control blowtorch flow and sedimentation time each layer thickness is controlled to be: sandwich layer 111 thickness are 2.96 μ m; First covering, 112 layer thicknesses are 1.69 μ m; Second covering, 113 layer thicknesses are at 57.87 μ m.By control drawing speed, water dropper temperature etc. naked glass optical fiber diameter is controlled at 125.03 μ m; The thickness of first coating 12 and second coating, 13 coated with resins is respectively 36.1 μ m and 23.8 μ m; The final finished fibre diameter is 245.02 μ m; Control by resin and condition of cure makes the Young modulus of the win resin protective layer 12 and second resin protective layer 13 be about 1.1MPa and 1.6MPa respectively, and elastic modulus is about 700MPa and 1200MPa respectively.Each performance parameter of present embodiment optical fiber is as follows: by wavelength X _cBe 1.248 μ m; Mode field diameter under the 1310nm wavelength is 6.71 μ m; It is 5.37 that characteristic parameter (MAC) value is decreased in bending resistance under 1310nm; Attenuation coefficient 0.368dB/km under 1310nm; Attenuation coefficient 0.205dB/km under 1550nm; Attenuation coefficient 0.209dB/km under 1625nm; Decay uncontinuity 0.01dB/km under 1310nm; Decay uncontinuity 0.01dB/km under 1550nm; Loose when 10 circles are measured with 15mm half, the macrobending loss 0.002dB under the 1550nm wavelength, the loss 0.015dB under the 1625nm wavelength; Loose when 1 circle is measured with 10mm half, macrobending loss＜0.002dB under the 1550nm wavelength, the loss 0.013dB under the 1625nm wavelength, loose when 1 circle is measured with 7.5mm half, macrobending loss＜0.004dB under the 1550nm wavelength, the loss 0.013dB under the 1625nm wavelength.Present embodiment optical fiber meets ITU.T sonet standard G.657.B, and this optical fiber has littler mode field diameter and better bend-insensitive performance, is particularly suitable for the transmission system of the Access Network of FTTX (Fiber to the home, FTTB space, Fiber To The Curb) etc.

It needs to be noted, the mode of the foregoing description only limits to describe embodiment, but the utility model is not confined to aforesaid way, therefore and those skilled in the art can modify in not breaking away from scope of the present utility model in view of the above easily, and scope of the present utility model should comprise the principle that the utility model discloses and the maximum magnitude of new feature.

Claims (8)

1, the single-mode fiber used of a kind of LAN (Local Area Network) and Access Network; by xsect is that the resin protective layer (12,13) that circular naked glass optical fiber (11) and two xsects that are enclosed in this naked glass optical fiber (11) periphery are annular constitutes; it is characterized in that described naked glass optical fiber (11) is that the covering (112,113) that circular sandwich layer (111) and two xsects are annular is formed by an xsect; the refractive index of described sandwich layer (111) is higher than the refractive index of two coverings (112,113), and the refringence (Δ of described sandwich layer (111) and first covering (112) ₁) greater than the refringence (Δ of first covering (112) with second covering (113) ₂), second covering is pure SiO ₂Form, the refractive index profile of sandwich layer (111) is power function and distributes, and the refractive index profile of two coverings all is ladder pattern distribution.

2, the single-mode fiber used of a kind of LAN (Local Area Network) according to claim 1 and Access Network is characterized in that the refringence (Δ of described sandwich layer (111) and first covering (112) ₁) between 0.0033～0.0072; Refringence (the Δ of first covering (112) and second covering (113) ₂) between-0.0016～0; The thickness of sandwich layer (a) is between 2.7～4.1 μ m; The thickness (b) of first covering (112) is between 0.5～2.3 μ m; The thickness (c) of second covering (113) is between 56.7～59.8 μ m.

3, the single-mode fiber used of a kind of LAN (Local Area Network) according to claim 1 and 2 and Access Network, the diameter that it is characterized in that described naked glass optical fiber (11) is between 124.3～125.7 μ m; The thickness of first resin protective layer (12) is 38 ± 1 μ m, and Young modulus is 1.1 ± 0.1MPa, and elastic modulus is 1.6 ± 0.1MPa; Thickness 22 ± 1 μ m of second resin protective layer (13), Young modulus is 700 ± 50MPa, elastic modulus is 1200 ± 100MPa; The external diameter of naked glass optical fiber is 125 ± 1 μ m; The diameter of finished product optical fiber is 242 ± 7 μ m.

4, the single-mode fiber used of a kind of LAN (Local Area Network) according to claim 1 and 2 and Access Network is characterized in that the refringence (Δ of described sandwich layer (111) and first covering (112) ₁) between 0.0034～0.0045; Refringence (the Δ of first covering (112) and second covering (113) ₂) between-0.0006～0; The thickness of sandwich layer is between 3.5～4.0 μ m; The thickness of first covering (112) is between 0.5～1.9 μ m; The thickness of second covering (113) is between 56.6～58.5 μ m; The external diameter of naked glass optical fiber is 125 ± 1 μ m; The diameter of finished product optical fiber is 242 ± 7 μ m.

5, the single-mode fiber used of a kind of LAN (Local Area Network) according to claim 4 and Access Network, it is characterized in that finished product optical fiber in the mode field diameter under the 1310nm wavelength (MFD) between 8.6 ± 0.4 μ m, its cutoff wavelength (λ _c) between 1180～1330nm; Loose when 10 circles are measured with 15mm half, the macrobending loss＜0.25dB of finished product optical fiber under the 1550nm wavelength, the macrobending loss＜1.0dB under the 1625nm wavelength; Loose when 1 circle is measured with 10mm half, the macrobending loss＜0.75dB of finished product optical fiber under the 1550nm wavelength, the macrobending loss＜1.5dB under the 1625nm wavelength.

6, the single-mode fiber used of a kind of LAN (Local Area Network) according to claim 1 and Access Network is characterized in that the refringence (Δ of described sandwich layer (111) and first covering (112) ₁) between 0.0058～0.0072; Refringence (the Δ of first covering (112) and second covering (113) ₂) between-0.0016～-0.0008; The thickness of sandwich layer is between 2.8～3.2 μ m; The thickness of first covering (112) is between 0.8～2.1 μ m; The thickness of second covering (113) is between 57.1～58.9 μ m; The external diameter of naked glass optical fiber is 125 ± 1 μ m; The diameter of finished product optical fiber is 242 ± 7 μ m.

7, the single-mode fiber used of a kind of LAN (Local Area Network) according to claim 6 and Access Network, it is characterized in that finished product optical fiber in the mode field diameter under the 1310nm wavelength (MFD) between 6.5 ± 0.5 μ m, its cutoff wavelength (λ _c) between 1180～1330nm; Loose when 10 circles are measured with 15mm half, the macrobending loss＜0.03dB of finished product optical fiber under the 1550nm wavelength, the macrobending loss＜0.1dB under the 1625nm wavelength; Loose when 1 circle is measured with 10mm half, the macrobending loss＜0.1dB of finished product optical fiber under the 1550nm wavelength, the macrobending loss＜0.2dB under the 1625nm wavelength; Loose when 1 circle is measured with 7.5mm half, the macrobending loss＜0.5dB of finished product optical fiber under the 1550nm wavelength, the macrobending loss＜1.0dB under the 1625nm wavelength.

8, the single-mode fiber used of a kind of LAN (Local Area Network) according to claim 1 and Access Network, it is characterized in that described sandwich layer (111) near the power exponent of the distribution power function of the subregional refractive index profile of central part between 3～5, near the power exponent of the distribution power function of the refractive index profile of first covering (112) subregion between-9～-8.

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