CN101226258B - Single mode fibre with low bending loss and low nonlinear effect - Google Patents

Abstract

The invention relates to a single mode fiber with low bend loss and low nonlinear effect, belonging to optical communication technical field, while prior fiber has limited bandwidth and is fail to meet the standard of prior G.656 fiber. The invention comprises a bare glass fiber and a resin protective layer surrounding the bare glass fiber. The inveniotn is characterized in that the bare glass fiber is composed of one core layer area and three clad layer areas, wherein the core layer area is composed of a low index concave area and a high index non-concave area, the first and second clad layer areas are pure SiO2 layers, the refractive index difference of the second clad layer is higher than the refractive index difference of the core layer area, the refractive index sections of the core layer area and the three clad layer areas are in step shape. The invention reasonably designs the core and clad layers of fiber to realize low bend loss and low nonlinear effect meeting prior G.656 fiber standard, high-speed transmission system and WDM system.

Description

The single-mode fiber of low bend loss, low nonlinear effects

Technical field

The present invention relates to a kind of optical fiber, belong to optical communication technique, particularly satisfy G.656 sonet standard, low bend loss, low nonlinear effects, as to be applicable to high rate data transmission system and wavelength-division multiplex system (WDM) single-mode fiber.

Background technology

The main optical fiber that is usually used in the transmission network construction at present has two kinds, promptly G.652 conventional single-mode fiber and non-zero dispersion displacement optical fiber G.655.Usually G.652 single-mode fiber is bigger in the chromatic dispersion of C-band 1530nm～1565nm and L-band 1565nm～1625nm, is generally 17～22ps/nmkm.Opening two-forty system such as 10Gb/s and 40Gb/s and during based on the wdm system of unipath two-forty, must adopting dispersion compensating fiber (DCF) to carry out dispersion compensation, the chromatic dispersion at 1550nm place on the whole circuit is reduced.But DCF can introduce bigger decay simultaneously, therefore must acquire image intensifer in the line again, and such make has increased the cost of system greatly.In addition, along with the application of fiber amplifier, surpass+the above light signal of 18dB is coupled into an optical fiber, and wavelength-division multiplex technique makes tens of even up to a hundred optical channels in the optical fiber.At this moment, higher luminous energy accumulates on the very little cross section, and optical fiber begins to present nonlinear characteristic, and becomes the key factor of final restriction transmission system performance.Particularly when radio frequency channel wavelength during near the optical fiber zero dispersion point, this phenomenon is more outstanding.

For avoiding near the non-linear effects the zero dispersion point, G.655 the zero dispersion point of optical fiber but to long wavelength or the displacement of short wavelength's direction, makes near the chromatic dispersion (the ITU-T standard is 0.1-6ps/nmkm) that presents a certain size 1550nm not near 1550nm.Like this, can significantly alleviate the influence that four ripples mix, help the transmission of dense wavelength division multiplexing system.Simultaneously, by near the control of the dispersion values the 1550nm, can guarantee that the signal that speed surpasses 10Gbit/s can restrictedly not transmitted more than the 300km by chromatic dispersion, and can in 1530nm～1565nm wavelength coverage, be applicable to WDM.

For further expanding WDM, the transmission bandwidth of dense wavelength division multiplexing system (DWDM) particularly, it is used wavelength is extended in the wider scope, necessary refractive index profile to optical fiber improves, reduce the CHROMATIC DISPERSION IN FIBER OPTICS slope coefficient, so that optical fiber all has the chromatic dispersion of less (non-zero) in wider scope.Under this background, Dispersion Flattened Fiber has obtained extensive studies, in " Effect of optical Kerr effect nonlinearity on LP11mode cutoff frequency of single-mode dispersion-shifted and dispersion-flattenedfibers; Optics Communications; Volume 127; Issues 1-3; 1 June 1996, Pages 25-30 ", inquired in the Dispersion Flattened Fiber Kerr effect to the influence by wavelength of single-mode fiber as S.K.Mondal etc.; S.K.Mondal etc. have proposed a kind of Dispersion Flattened Fiber of the W of having type cladding structure in " Interesting effect of optical Kerr nonlinearity in expanding single-mode regimeof optical fibers using dispersion-flattened profiles; Optics Communications; Volume 150; Issues 1-6; 1 May 1998; Pages 81-84 ", with G.655 compare the nonlinear effect that this optical fiber can more effective inhibition optical fiber; A.V.Belov has introduced at " Profile structure of single-mode fibers with low nonlinear properties forlong-haul communication lines; Optics Communications; Volume 161; Issues 4-6; 15March 1999, Pages 212-216 " and a kind ofly has been no more than ± 0.4ps nm in the chromatic dispersion of 1.53-1.56 mu m range inner fiber ^-1Km ^-1Optical fiber; The T.Kato of SUMITOMO CHEMICAL etc. are a kind of non-zero dispersion displacement optical fiber with dispersion flattene of complicated cross-section structure of report in " Dispersion flattened transmissionline consisting of wide-band non-zero dispersion shifted fiber and dispersioncompensating fiber module; Optical Fiber Technology; Volume 8; Issue 3; July 2002; Pages 231-239 ", the about 60 μ m of the useful area of this optical fiber ², at the chromatic dispersion gradient coefficient of C-band at 0.08ps/nm ²Below/the km, in the chromatic dispersion of 1500～1600nm scope inner fiber at 5～11ps/nm/km; China head company that flies also releases the G.655 optical fiber (post and telecommunications designing technique, 2002 the 9th phases) of the large effective area of a kind of being called as " big guarantor in fact ".These researchs have all promoted the WDM application technology to a certain extent to wideer wavelength coverage development.Putting before this, standard for further this type optical fiber of standard, and make it really to be applied to widely in the actual transmission line, Japan NTT and CLPAJ united in the ITU-TSG15 meeting of Geneva and proposed a kind of novel optical fiber that is called as G.656 of research in May, 2002.Compare with optical fiber G.655, this CHROMATIC DISPERSION IN FIBER OPTICS curve is more smooth, and abbe number littler (in 1460～1625nm scope between 2～14ps/nm/km) can better suppress stimulated scattering and Kerr effect.In addition, for the single-mode fiber that makes optical fiber G.656 and laid carries out effective welding, the mode field diameter of stipulating optical fiber G.656 is between 7～11 μ m.G.652 and the another widely used fiber products G.655 this optical fiber is expected to DWDM transmission is expanded in the whole wavelength coverage of 1460nm～1625nm, is considered to continue.

Recently, tentatively reach an agreement, also in succession relevant for the G.656 patent appearance of optical fiber about standard G.656.(international application no: PCT/JP98/03383), this fibre-optical dispersion coefficient is at 0.03ps/nm as " Dispersion Flattened Fiber " of SUMITOMO CHEMICAL ²/ km, less than 5ps/nm/km, the useful area of optical fiber can be controlled in about 45 μ m at the chromatic dispersion absolute value at 1550nm place ², but the useful area of this optical fiber is less than normal, and higher luminous energy accumulates on the less cross section, causes optical fiber to present nonlinear characteristic easily, thereby has limited bandwidth of an optical fiber; (application number: 200410016712.9), this CHROMATIC DISPERSION IN FIBER OPTICS slope is at-0.03～0.03ps/nm for and for example domestic patent " dispersion flattened single mode fiber of three wave length window negative dispersion " ²/ km, 1500nm～1600nm scope internal dispersion coefficient-4.0～-6.9ps/nm/km, though this CHROMATIC DISPERSION IN FIBER OPTICS curve ratio is more smooth, the absolute value of abbe number is less, this optical fiber also not exclusively satisfies the standard of current G.656 optical fiber.

Generally, for G.655 optical fiber and Dispersion Flattened Fiber, comprise two kinds of Dispersion Flattened Fibers of Sumitomo and Wang Yeheng application, in its refractive index profile structure, the refractive index of covering helps constraining light in the sandwich layer transmission so all a little less than the sandwich layer refractive index of optical fiber.Bartolomeo etc. then in the patented claim original text of " Optical fiber having low non-linearity forWDM transmission " (application number: US 2003/0128948 A1) a kind of refractive index of surrounding layer of optical fiber has been proposed a little more than the design philosophy of fiber core layer, pass through core, the suitable allotment of covering physical dimension and refractive index thereof, can obtain fully satisfying G.650 or the optical fiber of transmission performance standard G.655, and the optical fiber with this kind structure is comparatively loose to the requirement of manufacturing tolerance, yield rate is higher relatively, and the manufacturing cost of optical fiber also reduces relatively.But the sandwich layer of the optical fiber of addressing in this invention and cladding index all are parabolic distribution, and this parabolical shape index is bigger to Effect on Performance such as fibre-optical dispersion, ring wavelength and zero-dispersion wavelengths, thereby the design that this outsourcing is higher than sandwich layer to improve qualification rate, reduce cost beneficial, but parabolical shape has then limited the performance of this design philosophy superiority again to a certain extent, promptly cause manufacturing process comparatively complicated, and make that further improving optical fiber manufacturing qualification rate is restricted.

Summary of the invention

The technical assignment of the technical problem to be solved in the present invention and proposition is to overcome that bandwidth of an optical fiber that prior art exists is restricted, can not satisfies fully the standard of current G.656 optical fiber and the manufacturing process that causes because of parabolical shape is comparatively complicated, and make that further improving optical fiber makes the defective that qualification rate is restricted, provide a kind of feasible on technology, manufacturing tolerance require comparatively loose, manufacturing cost is comparatively cheap and can satisfy now the low bend loss about sonet standard G.656, the single-mode fiber of low nonlinear effects fully.For this reason, the present invention is by the following technical solutions:

The single-mode fiber of low bend loss, low nonlinear effects; comprise naked glass optical fiber and the resin protective layer that is enclosed in described naked glass optical fiber periphery; it is characterized in that described naked glass optical fiber is made up of a sandwich layer district and three clad regions; and the sandwich layer district is made up of refractive index lower depressed area and the higher non-depressed area of refractive index; first clad region and triple clad district are pure SiO2 floor; the second cladding region refractive index difference is higher than the refringence in sandwich layer district, and described sandwich layer district and three cladding region refractive index sections all are the notch cuttype sections.

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

Sandwich layer depressed area refringence (Δ c) is between 0.0035～0.0072, and permissible error is ± 2.6%; Sandwich layer depressed area thickness is between 0.9～2.1 μ m, and permissible error is ± 3.8%; The non-depressed area of sandwich layer refringence (Δ 1) is between 0.0081～0.0095, and permissible error is ± 2.1%; Promptly between 0.6～2.3 μ m, permissible error is ± 2.2% to the non-depressed area of sandwich layer thickness; First cladding thickness is between 0.8～2.3 μ m, and permissible error is ± 4.2%; The refringence of second covering (Δ 2) is between 0.0089～0.0107, and permissible error is ± 2.7%; Second cladding thickness is between 0.76～1.78 μ m, and permissible error is ± 3.5%; Triple clad thickness is between 57.2～58.8 μ m, and permissible error is ± 0.85%.

The refringence of second covering (Δ 2) is higher by 9%～14% than the non-depressed area of sandwich layer refringence (Δ 1).

Sandwich layer depressed area refringence (Δ c) is between 0.0037～0.0039, the non-depressed area of sandwich layer refringence (Δ 1) is between 0.0092～0.0096, the refringence of second covering (Δ 2) is between 0.0097～0.0100, sandwich layer depressed area diameter (a0) is between 4.04～4.36 μ m, the non-depressed area of sandwich layer diameter (a) is between 6.19～6.61 μ m, first cladding diameter (c1) is between 7.15～7.65 μ m, second cladding diameter (c2) is between 8.96～9.60 μ m, and (c3) is between 124.00～126.00 μ m between the triple clad.Useful area (A _Eff) greater than 80 μ m ²Nonlinear waveguide coefficient (γ) is less than 1.102W ^-1K ^-1Mode field diameter (MFD under 1550nm ₁₅₅₀) between 10.10～10.30 μ m.

Sandwich layer depressed area refringence (Δ c) is between 0.0034～0.0036, the non-depressed area of sandwich layer refringence (Δ 1) is between 0.0086～0.0090, the refringence of second covering (Δ 2) is between 0.0094～0.0100, sandwich layer depressed area diameter (a0) is between 3.85～4.15 μ m, the non-depressed area of sandwich layer diameter (a) is between 5.22～5.58 μ m, first cladding diameter (c1) is between 5.98～6.42 μ m, second cladding diameter (c2) is between 7.72～8.28 μ m, and (c3) is between 124.26～125.92 μ m between the triple clad.Bending resistance is decreased characteristic parameter (MAC) less than 5.9; When bending radius is 30mm, when the crooked number of turns is 100 circles, the maximum macrobending loss＜0.15dB under the 1625nm wavelength; Mode field diameter (MFD under 1550nm ₁₅₅₀) be 8.30～8.50 μ m.

Sandwich layer depressed area refringence (Δ c) is between 0.0071～0.0075, the non-depressed area of sandwich layer refringence (Δ 1) is between 0.0086～0.0090, the refringence of second covering (Δ 2) is between 0.0097～0.0100, sandwich layer depressed area diameter (a0) is between 1.92～2.08 μ m, the non-depressed area of sandwich layer diameter (a) is between 5.44～5.76 μ m, first cladding diameter (c1) is between 6.40～6.80 μ m, second cladding diameter (c2) is between 8.80～9.36 μ m, and (c3) is between 124.31～125.94 μ m between the triple clad.Useful area (A _Eff) greater than 65 μ m ²Bending resistance is decreased characteristic parameter (MAC) less than 7.1; When bending radius is 30mm, when the crooked number of turns was 100 circles, the maximum macrobending loss under the 1625nm wavelength was less than 0.25dB; Mode field diameter (MFD under 1550nm ₁₅₅₀) be 9.70～9.90 μ m.

Single-mode fiber of the present invention can be made of quartz glass core, quartz glass covering and the inside and outside two layers of resin of mixing, and wherein the sandwich layer of optical fiber and covering have particular structure.The sandwich layer of optical fiber has the non-depressed area of certain sunk area; First covering is pure SiO ₂Layer; Second cladding index is a little more than sandwich layer; Triple clad is that the surrounding layer of optical fiber is pure SiO ₂Layer.The refractive index of the sandwich layer and first covering can obtain by the different component of mixing.The external diameter of bare fibre is 125 ± 1 μ m.The diameter of finished product optical fiber is 245 ± 1 μ m.

When making this optical fiber, earlier according to the refractive index profile that designs, it is the refractive index of depressed area and non-depressed area in the sandwich layer, thickness, the thickness of first covering, second, the refractive index of triple clad, parameters such as thickness, determine the component of each layer doping, again respectively with the improvement vapour deposition process (MCVD) (or Plasma Enhanced Chemical Vapor Deposition (PECVD), PCVD) make the plug of the preform adhere to specification, with outside vapour deposition (OVD) or tiretube process (RIC) thus making the surrounding layer that is enclosed in the plug periphery obtains preform, on wire-drawer-tower this prefabricated rods is drawn into optical fiber more at last, this optical fiber applies the size that reaches design through twice UV-cured resin; , some row machineries, optics and chemistry become the optical fiber finished product after screening the back reel.

The invention has the beneficial effects as follows by sandwich layer and covering and reasonably design optical fiber, realized feasible on technology, manufacturing tolerance require comparatively loose, manufacturing cost is comparatively cheap and it is current about sonet standard G.656 and be applicable to the low bend loss of high rate data transmission system and wdm system, the single-mode fiber of low nonlinear effects to satisfy fully:

According to sonet standard, G.656 optical fiber mainly is to be better than G.655 optical fiber aspect the adverse effect of the nonlinear effect that suppresses optical fiber, and the former chromatic dispersion gradient is littler, and spendable wavelength is more wide.The big or small available nonlinear factor γ of the nonlinear effect of optical fiber weighs, and γ is more little unreasonablely to be thought.Generally, the γ of single-mode fiber can be simplified shown as formula (1):

$\mathrm{\γ}=\frac{2\mathrm{\π}{n}^{*}}{\mathrm{\λ}{A}_{\mathrm{eff}}}---\left(1\right)$

N in the formula ^*Nonlinear refraction rate coefficient for optical fiber.A _EffBe the useful area under wavelength X, i.e. the average area of transmitting optical power in the optical fiber.A _EffDetermine according to formula (2):

$A_{\mathrm{eff}}=\frac{2\mathrm{\π}{\left[{\∫}_0^{\∞}{\mathrm{\ψ}}^2\left(R\right)\mathrm{RdR}\right]}^2}{{\∫}_0^{\∞}{\mathrm{\ψ}}^4\left(R\right)\mathrm{RdR}}---\left(2\right)$

ψ in the formula (R) is a transmission optical waveguide equation in the optical fiber.

By formula (1) and (2) as can be known, reducing nonlinear factor γ can be by adjusting the optical fibre refractivity cross-section structure to change the n of optical fiber ^*Or A _EffSize realize.

On the other hand, along with the further popularization of optical fiber communication business, the enforcement soon 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.Jingyuan Wang etc. are at " Properties of index-guided PCF with air-core, Optics﹠amp; Laser Technology, Volume 39, Issue 2, March 2007, Pages 317-321 " and Unger C etc. at " Investigat ion of the microbending sensitivity of fibers.J.Light wavetechnology, 1994,14 (4): 591～596 " point out all in the paper that optical fiber hollow is comparatively favourable to the bending resistance of optical fiber.But as G.655 optical fiber and G.656 optical fiber, the hollow of optical fiber is difficult on technology realize that simultaneously, optical fiber hollow also can cause the mode field diameter of optical fiber and the performance between the chromatic dispersion to be difficult to coordinate for the non-zero dispersion displacement optical fiber of section complexity.The present invention has carried out critical design to the sandwich layer of optical fiber in view of the above, make the incomplete hollow of sandwich layer of optical fiber but have to a certain degree depression, thereby can also satisfy G.656 other requirements of sonet standard when making optical fiber of the present invention obtain excellent counter-bending drain 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 a mode field diameter (MFD) and by wavelength (λ _c) ratio, it defines as the formula (3):

MAC＝MFD/λ _c (3)

In view of the above, by to the size of fiber core layer, covering and the particular design of index distribution, reduced the MFD of optical fiber and increased the λ of optical fiber among the present invention _cThereby, realized the raising of the counter-bending drain performance of optical fiber.

Optical fiber of the present invention has unique refractive index profile, waveguide performance and anti-bending strength: the MAC value is no more than 7.5; Macrobend loss coefficient＜0.35dB/km under 1550nm; Between 2.2～13.5ps/nm/km, the chromatic dispersion gradient coefficient is not higher than 0.06ps/nm at the wavelength coverage internal dispersion coefficient of 1460nm～1625nm ²/ km; Useful area A _Eff＞50 μ m ²Nonlinear waveguide coefficient gamma＜2W ^-1K ^-1Compare with optical fiber G.655, the nonlinear effect performance of its bending resistance and anti-optical waveguide all is enhanced, and can use the DWDM technology in the whole wavelength coverage of 1460nm～1625nm.

Description of drawings

Figure 1A and 1B are respectively the diagrammatic cross-section of the optical fiber made according to an embodiment of the present invention and the diagrammatic cross-section of bare fibre.

Fig. 2 is the refractive index profile structural representation of bare fibre 11 among Fig. 1.

Fig. 3 A, 3B are used for other example of synoptic diagram 1 bare fibre 11 index distribution.

Figure 4 shows that optical fiber effective area A under fiber core layer of the present invention depressed area diameter a0 and the 1550nm _EffBetween relation curve.

Figure 5 shows that CHROMATIC DISPERSION IN FIBER OPTICS slope coefficient S under fiber core layer of the present invention depressed area diameter a0 and the 1550nm ₁₅₅₀Between relation curve.

Figure 6 shows that fibre-optical dispersion coefficient D under fiber core layer of the present invention depressed area diameter a0 and the 1550nm ₁₅₅₀Between relation curve.

Figure 7 shows that the relation curve between the optical fiber bending resistance characteristic quantity MAC value under fiber core layer of the present invention depressed area diameter a0 and the 1550nm.

Figure 8 shows that the relation curve between the nonlinear fiber waveguide coefficient gamma under fiber core layer of the present invention depressed area diameter a0 and the 1550nm.

Figure 9 shows that optical fiber effective area A under fiber core layer of the present invention depressed area refractive indices c and the 1550nm _EffBetween relation curve.

Figure 10 shows that CHROMATIC DISPERSION IN FIBER OPTICS slope coefficient S under fiber core layer of the present invention depressed area refractive indices c and the 1550nm ₁₅₅₀Between relation curve.

Figure 11 shows that the abbe number D under fiber core layer of the present invention depressed area refractive indices c and the optical fiber 1550nm ₁₅₅₀Between relation.

Figure 12 shows that the relation curve between the optical fiber bending resistance characteristic quantity MAC value under fiber core layer of the present invention depressed area refractive indices c and the 1550nm.

Figure 13 shows that the relation curve between the nonlinear fiber waveguide coefficient gamma under fiber core layer of the present invention depressed area refractive indices c and the 1550nm.

Figure 14 shows that optical fiber effective area A under fiber core layer diameter a of the present invention and the 1550nm _EffBetween relation curve.

Figure 15 shows that CHROMATIC DISPERSION IN FIBER OPTICS slope coefficient S under fiber core layer diameter a of the present invention and the 1550nm ₁₅₅₀Between relation curve.

Figure 16 shows that fibre-optical dispersion coefficient D under fiber core layer diameter a of the present invention and the 1550nm ₁₅₅₀Between relation curve.

Figure 17 shows that the relation curve between the optical fiber bending resistance characteristic quantity MAC value under fiber core layer diameter a of the present invention and the 1550nm.

Figure 18 shows that the relation curve between the nonlinear fiber waveguide coefficient gamma under fiber core layer diameter a of the present invention and the 1550nm.

Figure 19 shows that the non-depression of fiber core layer of the present invention removes optical fiber effective area A under refractive indices 1 and the 1550nm _EffBetween relation curve.

Figure 20 shows that the non-depression of fiber core layer of the present invention removes CHROMATIC DISPERSION IN FIBER OPTICS slope coefficient S under refractive indices 1 and the 1550nm ₁₅₅₀Between relation curve.

Shown in Figure 21ly be the abbe number D under the non-depressed area of fiber core layer of the present invention refractive indices 1 and the optical fiber 1550nm ₁₅₅₀Between relation.

Shown in Figure 22 is the relation curve between the optical fiber bending resistance characteristic quantity MAC value under the non-depressed area of fiber core layer of the present invention refractive indices 1 and the 1550nm.

Shown in Figure 23 is the relation curve between the nonlinear fiber waveguide coefficient gamma under the non-depressed area of fiber core layer of the present invention refractive indices 1 and the 1550nm.

Dispersion curve for the different embodiment of optical fiber of the present invention shown in Figure 24.

Embodiment

With reference to Figure 1A, optical fiber is defined as 10.Its structure comprises: the glass bare fibre 11 that is distributed in optical fiber 10 centers, and first coating 12 and second coating 13 that are enclosed in 11 peripheries, first coating 12 and second coating 13 are the polyacrylic resin material, can solidify by ultraviolet curing or other method to make.With reference to Figure 1B, bare fibre 11 comprises the index dip district 111 of the sandwich layer of optical fiber, the non-index dip district 112 of sandwich layer, pure SiO ₂First clad region 113, refractive index be higher than second clad region 114 and the pure SiO of sandwich layer ₂Triple clad district 115,115 also can be described as surrounding layer.

The present invention can adopt MCVD (also available PCVD or other similar approach replace) method to prepare the optical fiber prefabricated rod mandrel with refractive index profile structure shown in Figure 2, and then make pure SiO with the OVD 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 MCVD (or PCVD) to make preform: in MCVD or PCVD technology, by SiCl at blowtorch in conjunction with the method for OVD ₄Doped with Ge Cl in the raw material ₄With the refractive indices c of suitable raising sandwich layer depressed area 111, and the sedimentary deposit size (being specially diameter a0) by parameters such as sedimentation time and material flow control sandwich layer depressed area 111; By adjusting GeCl ₄Doping with the size of the refractive indices 1 of adjusting the non-depressed area 112 of sandwich layer, and (be specially diameter a) by the sedimentary deposit size of the non-depressed area 112 of parameters such as sedimentation time and material flow control sandwich layer; Stop GeCl ₄Feed is with pure SiCl ₄For raw material continues spraying making first covering 113 to sedimentary deposit, and control the sedimentary deposit size (being specially diameter c1) of first covering 113 by parameters such as sedimentation time and material flows; Doped with Ge Cl in raw material again ₄, and by adjusting GeCl ₄Doping with the size of the refractive indices 2 of adjusting second covering 114, control the sedimentary deposit size (being specially diameter c2) of second covering 114 by parameters such as sedimentation time and material flows; Stop GeCl ₄Feed is with pure SiCl ₄For raw material continues spraying making the segment thickness of triple clad 115 to sedimentary deposit, and control the size (being specially diameter c3) of the sedimentary deposit of triple clad 115 these parts, to prepare plug by parameters such as sedimentation time and material flows.Then, calculate according to the size of above-mentioned gained plug and the thickness of optical fiber triple clad 115 another part adopt the OVD technology 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 MCVD (or PCVD) 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 the identical method of above-mentioned MCVD or PCVD to make plug; 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 applied in two coats different hardness promptly gets optical fiber simultaneously.

With reference to Fig. 2 and Fig. 3, optical fiber of the present invention has unique refractive index profile structure.Usually, in the refractive index profile structure of zero dispersion shift fiber, the refractive index of covering is all a little less than the sandwich layer refractive index of optical fiber, but in the refractive index profile of optical fiber of the present invention, the refractive index of second covering 114 is a little more than the refractive index of sandwich layer, this design has improved the range of tolerable variance of each important parameter in the fibre profile structure, makes the control of manufacturing be more prone to, and has improved the qualification rate of product.In the present invention, have the G.656 optical fiber of this kind structure, require sandwich layer depressed area 111 refractive indices c between 0.0035～0.0072, permissible error is ± 2.6%; The thickness of sandwich layer depressed area 111 be a0/2 between 0.9～2.1 μ m, permissible error is ± 3.8%.The non-depressed area of sandwich layer 112 refractive indices 1 are between 0.0081～0.0095, and permissible error is ± 2.1%; Promptly (a-a0)/2 are between 0.6～2.3 μ m for the thickness of the non-depressed area 112 of sandwich layer, and permissible error is ± 2.2%.First covering 113 is pure SiO ₂Layer, its refringence is 0; The thickness of first covering 113 i.e. (c1-a)/2, and between 0.8～2.3 μ m, permissible error is ± 4.2%.The refractive indices 2 of second covering 114 is between 0.0089～0.0107, and permissible error is ± 2.7%; Promptly (c2-c1)/2 are between 0.76～1.78 μ m for the thickness of second covering 114, and permissible error is ± 3.5%; Triple clad 115 is that surrounding layer also is pure SiO ₂Layer, promptly (c3-c2)/2 are between 57.2～58.8 μ m for its thickness, and permissible error is ± 0.85%.Therefore triple clad 115 thickness can not have too big influence to the qualification rate of product by suitably corrections such as polishings after the prefabricated rods manufacturing is finished.The refractive indices 2 of sandwich layer depressed area 111 refractive indices c, sandwich layer non-depressed area 112 refractive indices 1 and second covering 114 calculates with following formula respectively:

$\mathrm{\&Delta;c}=\frac{\mathrm{nc}-\mathrm{<figure-callout\; id="0"\; label="n"\; filenames="S07166730120070205E000021.png,S07166730120070205E000022.png"\; state="\{\{state\}\}">n</figure-callout>}0}{\mathrm{nc}}\&times;100\%---\left(4\right)$

$\mathrm{\&Delta;}1=\frac{n1-n0}{\mathrm{<figure-callout\; id="1"\; label="n"\; filenames="S07166730120070205E000052.png"\; state="\{\{state\}\}">n</figure-callout>}1}\&times;100\%---\left(5\right)$

$\mathrm{\&Delta;}2=\frac{n2-n0}{\mathrm{<figure-callout\; id="2"\; label="n"\; filenames="S07166730120070205E000052.png,S07166730120070205E000132.png"\; state="\{\{state\}\}">n</figure-callout>}2}\&times;100\%---\left(6\right)$

N0 is pure SiO in the formula ₂Refractive index, nc is the refractive index of sandwich layer depressed area, n1 is the refractive index of the non-depressed area of sandwich layer, n2 is the refractive index of second covering.

Adopt the relation curve of the structure of optical fiber of above-mentioned technology preparation and performance such as Fig. 4～shown in Figure 23.

Curve shown in Figure 4 is the approximately linear shape, demonstrates optical fiber effective area A under fiber core layer of the present invention depressed area diameter a0 and the 1550nm _EffBetween be proportional relationship preferably.

Curve shown in Figure 5 is the approximately linear shape, demonstrates CHROMATIC DISPERSION IN FIBER OPTICS slope coefficient S under fiber core layer of the present invention depressed area diameter a0 and the 1550nm ₁₅₅₀Between the approximate reverse proportionate relationship.

Curve shown in Figure 6 is the approximately linear shape, demonstrates the abbe number D under fiber core layer of the present invention depressed area diameter a0 and the 1550nm ₁₅₅₀Between be proportional relationship preferably.

Curve shown in Figure 7 is approximate parabolic shape, demonstrates the relation that optical fiber MAC value of the present invention reduces with the increase of fiber core layer depressed area diameter a0.

Curve shown in Figure 8 is the approximately linear shape, demonstrates the relation that nonlinear fiber waveguide coefficient gamma of the present invention reduces with the increase of fiber core layer depressed area diameter a0.

Curve shown in Figure 9 is the curve shape of approximate exponential function, demonstrates the useful area A of optical fiber of the present invention under 1550nm _EffThe variation relation that reduces with the increase of sandwich layer depressed area refractive indices c.

Curve shown in Figure 10 is approximate parabolical curve shape, demonstrates the chromatic dispersion gradient coefficient S of optical fiber of the present invention under 1550nm ₁₅₅₀The variation relation that increases with the increase of sandwich layer depressed area refractive indices c.

Curve shown in Figure 11 is the near linear shape, demonstrates the abbe number D under fiber core layer of the present invention depressed area refractive indices c and the 1550nm ₁₅₅₀Between be proportional relationship preferably.

Curve shown in Figure 12 is approximate parabolical curve shape, demonstrates the variation relation that the MAC of optical fiber of the present invention under 1550nm increases with the increase of sandwich layer depressed area refractive indices c.

Curve shown in Figure 13 is approximate parabolical curve shape, the variation relation that the nonlinear waveguide coefficient gamma that demonstrates optical fiber of the present invention increases with the increase of sandwich layer depressed area refractive indices c.

Curve shown in Figure 14 is approximate parabolical curve shape, demonstrates the useful area A of optical fiber of the present invention under 1550nm _EffThe variation relation that increases with fiber core layer diameter a.

Curve shown in Figure 15 is the irregular curve shape, demonstrates the chromatic dispersion gradient coefficient S of optical fiber of the present invention under 1550nm ₁₅₅₀Increase and the variation relation that reduces earlier afterwards to increase with fiber core layer diameter a.

Curve shown in Figure 16 is approximate parabolic shape, demonstrates the abbe number D of optical fiber of the present invention under 1550nm ₁₅₅₀The variation relation that increases with fiber core layer diameter a.

Curve shown in Figure 17 is the irregular curve shape, demonstrates optical fiber MAC value of the present invention and increases the variation relation that reduces with fiber core layer diameter a.

Curve shown in Figure 180 is the curve shape of approximate logarithm, demonstrates nonlinear fiber waveguide coefficient gamma of the present invention and increases the variation relation that reduces with fiber core layer diameter a.

Curve shown in Figure 19 is approximate parabolic shape, demonstrates the useful area A of optical fiber of the present invention under 1550nm _EffThe variation relation that goes the increase of refractive indices 1 to increase with the non-depression of fiber core layer.

Curve shown in Figure 20 is the curve shape of approximate logarithmic function, demonstrates the chromatic dispersion gradient coefficient S of optical fiber of the present invention under 1550nm ₁₅₅₀Go the increase of refractive indices 1 and the variation relation that reduces earlier with the non-depression of fiber core layer.

Curve shown in Figure 21 is the irregular curve shape, demonstrates the abbe number D of optical fiber of the present invention under 1550nm ₁₅₅₀The relation of going refractive indices 1 to increase with the non-depression of sandwich layer.

Curve shown in Figure 22 is irregular curve shape, demonstrates that the MAC of optical fiber of the present invention under 1550nm goes the increase of refractive indices 1 with the non-depression of fiber core layer and the variation relation that reduces earlier afterwards to increase.

Curve shown in Figure 23 is the near linear shape, demonstrates the variation relation that nonlinear fiber waveguide coefficient gamma of the present invention goes the increase of refractive indices 1 to reduce with the non-depression of fiber core layer.

Embodiment 1:

Adopt MCVD (or PCVD) to make plug, OVD (or RIC) technology is made the technology of surrounding layer and is made preform.When deposition sandwich layer depressed area 111, at raw material SiCl ₄The middle fixed GeCl of an amount that mixes ₄Making the sandwich layer depressed area value of refractive indices c under the 632.8nm wavelength is 0.0038; When the non-depressed area 112 of deposition sandwich layer, regulate GeCl ₄Doping to make the value of the non-depressed area of sandwich layer refractive indices 1 under the 632.8nm wavelength be 0.0094; When deposition first clad region 113, use pure SiCl ₄Raw material; When deposition second clad region 114, at raw material SiCl ₄Middle certain GeCl that mixes ₄Making the value of the second cladding index difference Δ 2 under the 632.8nm wavelength is 0.010; When deposition triple clad district 115, use pure SiCl ₄Raw material.By control blowtorch flow and sedimentation time each layer thickness is controlled to be: sandwich layer depressed area 111 layer thicknesses are 2.10 μ m; The non-depressed area of sandwich layer 112 layer thicknesses are 1.1 μ m; First clad region, 113 layer thicknesses are 0.50 μ m; Second clad region, 114 layer thicknesses are at 0.94 μ m; Triple clad district 115 layer thicknesses are 57.86 μ m.By control drawing speed, water dropper temperature etc. the bare fibre diameter is controlled at 125 μ m; The thickness that guarantees first coating 12 and second coating, 13 coated with resins all is about 30 μ m; The final finished fibre diameter is 245 μ m; Control by resin and condition of cure makes the Young modulus of the win coating 12 and second coating 13 be about 1.2MPa and 760MPa respectively, and elastic modulus is respectively 1.1MPa and 1400MPa.Each performance parameter of present embodiment optical fiber is as follows: useful area is 81 μ m ²Under the 1550nm wavelength, nonlinear factor γ is 1.03W ^-1Km ^-1Zero-dispersion wavelength λ ₀Be 1.35 μ m; By wavelength X c is 1.362 μ m; Chromatic dispersion gradient coefficient S under the 1550nm wavelength ₁₅₅₀Be 0.04485ps/nm ²/ km; Mode field diameter MFD under the 1550nm wavelength ₁₅₅₀Be 10.21 μ m; In the wavelength coverage of 1460nm～1625nm, abbe number is between 6.19～13.17ps/nm/km; It is 7.49 that characteristic parameter (MAC) value is decreased in bending resistance under 1550nm; When bending radius is 30mm, when the crooked number of turns was 100 circles, the maximum macrobending loss under the 1625nm wavelength was 0.29dB.Present embodiment CHROMATIC DISPERSION IN FIBER OPTICS curve is shown in 1 optical fiber of embodiment among Figure 24.The useful area of present embodiment optical fiber is about 2 times of similar optical fiber effective area, the transmission density of light in can more effective reduction optical fiber, and from the generation of effective inhibition nonlinear optical phenomena, therefore this optical fiber is specially adapted to high power, the dwdm system of long Distance Transmission or the soliton transmission system of wavelength multiplexing.

Embodiment 2

Adopt MCVD (or PCVD) to make plug, OVD (or RIC) technology is made the technology of surrounding layer and is made preform.When deposition sandwich layer depressed area 111, at raw material SiCl ₄The middle fixed GeCl of an amount that mixes ₄Making the sandwich layer depressed area value of refractive indices c under the 632.8nm wavelength is 0.0035; When the non-depressed area 112 of deposition sandwich layer, regulate GeCl ₄Doping to make the value of the non-depressed area of sandwich layer refractive indices 1 under the 632.8nm wavelength be 0.0088; When deposition first clad region 113, use pure SiCl ₄Raw material; When deposition second clad region 114, at raw material SiCl ₄Middle certain GeCl that mixes ₄Make the value of the second cladding index difference Δ 2 under the 632.8nm wavelength 0.0097; When deposition triple clad district 115, use pure SiCl ₄Raw material.By control blowtorch flow and sedimentation time each layer thickness is controlled to be: sandwich layer depressed area 111 layer thicknesses are 2.00 μ m; The non-depressed area of sandwich layer 112 layer thicknesses are 0.70 μ m; First clad region, 113 layer thicknesses are 0.40 μ m; Second clad region, 114 layer thicknesses are at 0.9 μ m; Triple clad district 115 layer thicknesses are at 58.50 μ m.By control drawing speed, water dropper temperature etc. the bare fibre diameter is controlled at 125 μ m; The thickness that guarantees first coating 12 and second coating, 13 coated with resins all is about 30 μ m; The final finished fibre diameter is 245 μ m; Control by resin and condition of cure makes the Young modulus of the win coating 12 and second coating 13 be about 1.2MPa and 760MPa respectively, and elastic modulus is respectively 1.1MPa and 1400MPa.Each performance parameter of present embodiment optical fiber is as follows: useful area is 53 μ m ²Under the 1550nm wavelength, nonlinear factor γ is 1.76W ^-1Km ^-1Zero-dispersion wavelength λ ₀Be 1.36 μ m; By wavelength X c is 1.437 μ m; Chromatic dispersion gradient coefficient S under the 1550nm wavelength ₁₅₅₀Be 0.04534ps/nm ²/ km; Mode field diameter MFD under the 1550nm wavelength ₁₅₅₀Be 8.34 μ m; In the wavelength coverage of 1460nm～1625nm, abbe number is between 4.26～12.71ps/nm/km; It is 5.81 that characteristic parameter (MAC) value is decreased in bending resistance under 1550nm; When bending radius is 30mm, when the crooked number of turns was 100 circles, the maximum macrobending loss under the 1625nm wavelength was 0.14dB.Present embodiment CHROMATIC DISPERSION IN FIBER OPTICS curve is shown in 2 optical fiber of embodiment among Figure 24.Present embodiment optical fiber is except that possessing routine G.656 the optical fiber properties, the distinguishing feature that also has little MAC value, its counter-bending drain performance also accordingly significantly is better than the G.656 optical fiber that other can get, so present embodiment optical fiber is specially adapted to optical fiber wiring relative complex or needs other special places of fibre-optical bending.

Embodiment 3

Adopt MCVD (or PCVD) to make plug, OVD (or RIC) technology is made the technology of surrounding layer and is made preform.When deposition sandwich layer depressed area 111, at raw material SiCl ₄The middle fixed GeCl of an amount that mixes ₄Making the sandwich layer depressed area value of refractive indices c under the 632.8nm wavelength is 0.0073; When the non-depressed area 112 of deposition sandwich layer, regulate GeCl ₄Doping to make the value of the non-depressed area of sandwich layer refractive indices 1 under the 632.8nm wavelength be 0.0088; When deposition first clad region 113, use pure SiCl ₄Raw material; When deposition second clad region 114, at raw material SiCl ₄Middle certain GeCl that mixes ₄Make the value of the second cladding index difference Δ 2 under the 632.8nm wavelength 0.0010; When deposition triple clad district 115, use pure SiCl ₄Raw material.By control blowtorch flow and sedimentation time each layer thickness is controlled to be: sandwich layer depressed area 111 layer thicknesses are 1.00 μ m; The non-depressed area of sandwich layer 112 layer thicknesses are 1.80 μ m; First clad region, 113 layer thicknesses are 0.50 μ m; Second clad region, 114 layer thicknesses are at 1.24 μ m; Triple clad district 115 layer thicknesses are at 58.02 μ m.By control drawing speed, water dropper temperature etc. the bare fibre diameter is controlled at 125 μ m; The thickness that guarantees first coating 12 and second coating, 13 coated with resins all is about 30 μ m; The final finished fibre diameter is 245 μ m; Control by resin and condition of cure makes the Young modulus of the win coating 12 and second coating 13 be about 1.2MPa and 760MPa respectively, and elastic modulus is respectively 1.1MPa and 1400MPa.Each performance parameter of present embodiment optical fiber is as follows: useful area is 68 μ m ²Nonlinear factor γ is 1.37W ^-1Km ^-1Zero-dispersion wavelength λ.Be 1.39 μ m; By wavelength X c is 1.40 μ m; Chromatic dispersion gradient coefficient S under the 1550nm wavelength ₁₅₅₀Be 0.05207ps/nm ²/ km; Mode field diameter MFD under the 1550nm wavelength ₁₅₅₀Be 9.76 μ m; In the wavelength coverage of 1460nm～1625nm, abbe number is between 2.43～11.51ps/nm/km; It is 7.02 that characteristic parameter (MAC) value is decreased in bending resistance under 1550nm; When bending radius is 30mm, when the crooked number of turns was 100 circles, the maximum macrobending loss under the 1625nm wavelength was 0.23dB.Present embodiment CHROMATIC DISPERSION IN FIBER OPTICS curve is shown in 3 optical fiber of embodiment among Figure 24.Present embodiment optical fiber is the trade-off of embodiment 1 and embodiment 2 described optical fiber, it not only has relatively large useful area but also less relatively MAC value is arranged, therefore the performance of its anti-nonlinear effect and counter-bending drain performance are also between above-mentioned two kinds of optical fiber, its combination property is preferable, therefore has more the potential that is widely used.

Except that above-mentioned property, optical fiber of the present invention all has following common sex character:

The decay unevenness: on optical fiber back scattering curve, the maximal value of the difference of the pad value of average 500m is not more than 0.05dB on actual measurement pad value on the 500m length and the total length arbitrarily; Cladding diameter: 125 ± 1 μ m; Core concentricity error :≤0.8 μ m; Non-circularity of cladding :≤0.2%; Screening stress: 〉=0.69GPa; Attenuation coefficient :≤0.4dB/km@1460nm; ≤ 0.35dB/km@1550nm; ≤ 0.4dB/km@1625nm; The decay two ends are poor: two-way test is averaged≤0.05dB/km; Polarization mode dispersion (PMD _Q) :≤0.15ps/km ^1/2@1550nm; Cable optical fiber cutoff wavelength (λ cc) :≤1450nm; Use operation wavelength: 1460nm～1625nm.

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

Claims (11)

1. the single-mode fiber of low bend loss, low nonlinear effects; the resin protective layer (12,13) that comprises naked glass optical fiber (11) and be enclosed in described naked glass optical fiber periphery; it is characterized in that described naked glass optical fiber (11) is made up of a sandwich layer district and three clad regions (113,114,115); and the sandwich layer district is made up of lower depressed area of refractive index (111) and the higher non-depressed area (112) of refractive index, and first clad region (113) and triple clad district (115) are pure SiO ₂Layer, the refractive indices 2 of second clad region (114) is higher than the refringence in sandwich layer district, and described sandwich layer district and three cladding region refractive index sections all are the notch cuttype sections;

Sandwich layer depressed area refractive indices c is between 0.0035～0.0072; Sandwich layer depressed area thickness is between 0.9～2.1 μ m; The non-depressed area of sandwich layer refractive indices 1 is between 0.0081～0.0095; The non-depressed area of sandwich layer thickness is promptly between 0.6～2.3 μ m; First cladding thickness is between 0.8～2.3 μ m; The refractive indices 2 of second covering is between 0.0089～0.0107; Second cladding thickness is between 0.76～1.78 μ m; Triple clad thickness is between 57.2～58.8 μ m;

The refractive indices 2 of sandwich layer depressed area 111 refractive indices c, sandwich layer non-depressed area 112 refractive indices 1 and second covering 114 calculates with following formula respectively:

$\mathrm{\&Delta;c}=\frac{\mathrm{nc}-n0}{\mathrm{nc}}\&times;100\%,$ $\mathrm{\&Delta;}1=\frac{n1-n0}{n1}\&times;100\%,$ $\mathrm{\&Delta;}2=\frac{n2-n0}{n2}\&times;100\%,$

N0 is pure SiO in the formula ₂Refractive index, nc is the refractive index of sandwich layer depressed area, n1 is the refractive index of the non-depressed area of sandwich layer, n2 is the refractive index of second covering.

2. the single-mode fiber of low bend loss according to claim 1, low nonlinear effects is characterized in that the refractive indices 2 of second covering is higher by 9%～14% than the non-depressed area of sandwich layer refractive indices 1.

3. the single-mode fiber of low bend loss, low nonlinear effects; the resin protective layer (12,13) that comprises naked glass optical fiber (11) and be enclosed in described naked glass optical fiber periphery; it is characterized in that described naked glass optical fiber (11) is made up of a sandwich layer district and three clad regions (113,114,115); and the sandwich layer district is made up of lower depressed area of refractive index (111) and the higher non-depressed area (112) of refractive index, and first clad region (113) and triple clad district (115) are pure SiO ₂Layer, the refringence of second clad region (114) is higher than the refringence in sandwich layer district, and described sandwich layer district and three cladding region refractive index sections all are the notch cuttype sections;

Sandwich layer depressed area refractive indices c is between 0.0037～0.0039, the non-depressed area of sandwich layer refractive indices 1 is between 0.0092～0.0096, the refractive indices 2 of second covering is between 0.0097～0.0100, sandwich layer depressed area diameter (a0) is between 4.04～4.36 μ m, the non-depressed area of sandwich layer diameter (a) is between 6.19～6.61 μ m, first cladding diameter (c1) is between 7.15～7.65 μ m, second cladding diameter (c2) is between 8.96～9.60 μ m, and triple clad diameter (c3) is between 124.00～126.00 μ m;

The refractive indices 2 of sandwich layer depressed area 111 refractive indices c, sandwich layer non-depressed area 112 refractive indices 1 and second covering 114 calculates with following formula respectively:

$\mathrm{\&Delta;c}=\frac{\mathrm{nc}-n0}{\mathrm{nc}}\&times;100\%,$ $\mathrm{\&Delta;}1=\frac{n1-n0}{n1}\&times;100\%,$ $\mathrm{\&Delta;}2=\frac{n2-n0}{n2}\&times;100\%,$

N0 is pure SiO in the formula ₂Refractive index, nc is the refractive index of sandwich layer depressed area, n1 is the refractive index of the non-depressed area of sandwich layer, n2 is the refractive index of second covering.

4. the single-mode fiber of low bend loss according to claim 3, low nonlinear effects is characterized in that useful area (A _Eff) greater than 80 μ m ²Nonlinear waveguide coefficient (γ) is less than 1.102W ^-1K ^-1Mode field diameter (MFD under 1550nm ₁₅₅₀) between 10.10～10.30 μ m.

5. the single-mode fiber of low bend loss according to claim 3, low nonlinear effects is characterized in that the refringence of second covering is higher by 9%～14% than the non-depressed area of sandwich layer refringence.

6. the single-mode fiber of low bend loss, low nonlinear effects; the resin protective layer (12,13) that comprises naked glass optical fiber (11) and be enclosed in described naked glass optical fiber periphery; it is characterized in that described naked glass optical fiber (11) is made up of a sandwich layer district and three clad regions (113,114,115); and the sandwich layer district is made up of lower depressed area of refractive index (111) and the higher non-depressed area (112) of refractive index, and first clad region (113) and triple clad district (115) are pure SiO ₂Layer, the refringence of second clad region (114) is higher than the refringence in sandwich layer district, and described sandwich layer district and three cladding region refractive index sections all are the notch cuttype sections;

Sandwich layer depressed area refractive indices c is between 0.0034～0.0036, the non-depressed area of sandwich layer refractive indices 1 is between 0.0086～0.0090, the refractive indices 2 of second covering is between 0.0094～0.0100, sandwich layer depressed area diameter (a0) is between 3.85～4.15 μ m, the non-depressed area of sandwich layer diameter (a) is between 5.22～5.58 μ m, first cladding diameter (c1) is between 5.98～6.42 μ m, second cladding diameter (c2) is between 7.72～8.28 μ m, and (c3) is between 124.26～125.92 μ m between the triple clad;

The refractive indices 2 of sandwich layer depressed area 111 refractive indices c, sandwich layer non-depressed area 112 refractive indices 1 and second covering 114 calculates with following formula respectively:

$\mathrm{\&Delta;c}=\frac{\mathrm{nc}-n0}{\mathrm{nc}}\&times;100\%,$ $\mathrm{\&Delta;}1=\frac{n1-n0}{n1}\&times;100\%,$ $\mathrm{\&Delta;}2=\frac{n2-n0}{n2}\&times;100\%,$

N0 is pure SiO in the formula ₂Refractive index, nc is the refractive index of sandwich layer depressed area, n1 is the refractive index of the non-depressed area of sandwich layer, n2 is the refractive index of second covering.

7. the single-mode fiber of low bend loss according to claim 6, low nonlinear effects is characterized in that bending resistance damage characteristic parameter (MAC) is less than 5.9; When bending radius is 30mm, when the crooked number of turns is 100 circles, the maximum macrobending loss＜0.15dB under the 1625nm wavelength; Mode field diameter (MFD under 1550nm ₁₅₅₀) be 8.30～8.50 μ m.

8. the single-mode fiber of low bend loss according to claim 6, low nonlinear effects is characterized in that the refringence of second covering is higher by 9%～14% than the non-depressed area of sandwich layer refringence.

9. the single-mode fiber of low bend loss, low nonlinear effects; the resin protective layer (12,13) that comprises naked glass optical fiber (11) and be enclosed in described naked glass optical fiber periphery; it is characterized in that described naked glass optical fiber (11) is made up of a sandwich layer district and three clad regions (113,114,115); and the sandwich layer district is made up of lower depressed area of refractive index (111) and the higher non-depressed area (112) of refractive index, and first clad region (113) and triple clad district (115) are pure SiO ₂Layer, the refringence of second clad region (114) is higher than the refringence in sandwich layer district, and described sandwich layer district and three cladding region refractive index sections all are the notch cuttype sections;

Sandwich layer depressed area refractive indices c is between 0.0071～0.0075, the non-depressed area of sandwich layer refractive indices 1 is between 0.0086～0.0090, the refractive indices 2 of second covering is between 0.0097～0.0100, sandwich layer depressed area diameter (a0) is between 1.92～2.08 μ m, the non-depressed area of sandwich layer diameter (a) is between 5.44～5.76 μ m, first cladding diameter (c1) is between 6.40～6.80 μ m, second cladding diameter (c2) is between 8.80～9.36 μ m, and (c3) is between 124.31～125.94 μ m between the triple clad;

The refractive indices 2 of sandwich layer depressed area 111 refractive indices c, sandwich layer non-depressed area 112 refractive indices 1 and second covering 114 calculates with following formula respectively:

$\mathrm{\&Delta;c}=\frac{\mathrm{nc}-n0}{\mathrm{nc}}\&times;100\%,$ $\mathrm{\&Delta;}1=\frac{n1-n0}{n1}\&times;100\%,$ $\mathrm{\&Delta;}2=\frac{n2-n0}{n2}\&times;100\%,$

N0 is pure SiO in the formula ₂Refractive index, nc is the refractive index of sandwich layer depressed area, n1 is the refractive index of the non-depressed area of sandwich layer, n2 is the refractive index of second covering.

10. the single-mode fiber of low bend loss according to claim 9, low nonlinear effects is characterized in that useful area (A _Eff) greater than 65 μ m ²Bending resistance is decreased characteristic parameter (MAC) less than 7.1; When bending radius is 30mm, when the crooked number of turns was 100 circles, the maximum macrobending loss under the 1625nm wavelength was less than 0.25dB; Mode field diameter (MFD under 1550nm ₁₅₅₀) be 9.70～9.90 μ m.

11. the single-mode fiber of low bend loss according to claim 9, low nonlinear effects is characterized in that the refringence of second covering is higher by 9%～14% than the non-depressed area of sandwich layer refringence.

Images