CN104898201A - Ultralow attenuation large-effective-area single-mode optical fiber - Google Patents

Abstract

The present invention relates to an ultralow attenuation large-effective-area single-mode optical fiber. The ultralow attenuation large-effective-area single-mode optical fiber comprises a core layer and wrapping layers, and is characterized in that a radius R1 of the core layer is 4.5-6.5 [mu]m, [delta]1 of the core layer is -0.05% to 0.10%, the core layer is wrapped from inside to outside in turn by an inner wrapping layer, a first sunken inner wrapping layer, a middle inner wrapping layer, a second sunken inner wrapping layer, an auxiliary outer wrapping layer and an outer wrapping layer, a radius R3 of the inner wrapping layer is 8.5-14 [mu]m, [delta]2 is -0.35% to -0.12%, an radius R3 of the first sunken inner wrapping layer is 13-22[mu]m, [delta]3 is -0.7% to -0.30%, a radius R4 of the middle inner wrapping layer is 14-23[mu]m, [delta]4 is -0.40% to -0.15%, a radius R5 of the second sunken inner wrapping layer is 28-30 [mu]m, [delta]5 is -0.6% to -0.25%, a radius R6 of the auxiliary outer wrapping layer is 35-50[mu]m, [delta]6 is -0.55% to -0.15%, and the outer wrapping layer is a pure silicon dioxide glass layer. The ultralow attenuation large-effective-area single-mode optical fiber is low in attenuation and large in effective area, and has excellent bending loss and dispersion characteristics, and cabling cut-off wavelength is smaller than 1530 nm.

Description

A kind of single-mode fiber of ultralow attenuation large effective area

Technical field

The present invention relates to optical fiber transmission technique field, be specifically related to a kind of single-mode fiber with ultralow decay and large effective area.

Background technology

Along with increasing rapidly of IP network data service, operator improves constantly for the demand of transmission capacity, and in existing network, single fiber capacity is approaching ultimate value 100Tbps gradually.100G transmission system has started to enter the commercial first year.How on the basis of 100G signal transmission, to increase transmission capacity further, be the focus that each system equipment business and operator pay close attention to.

In 100G and super 100G system, receiving end adopts coherent reception and Digital Signal Processing (DSP), the dispersion that can accumulate in the whole transmitting procedure of digital compensation in the electrical domain and polarization mode dispersion (PMD); The baud rate of signal by adopting the multiplexing and various high-order modulating of polarization mode to reduce signal, such as PM-QPSK, PDM-16QAM, PDM-32QAM, even PDM-64QAM and CO-OFDM.But high-order modulating is very responsive to nonlinear effect, therefore Optical Signal To Noise Ratio (OSNR) is had higher requirement.Introduce low-loss large effective area fiber, the effect improving OSNR and reduction nonlinear effect can be brought when employing high power density system for system, nonlinear factor is the parameter of the system performance quality caused for assessment of nonlinear effect, and it is defined as n2/A _eff.Wherein, n2 is the nonlinear refraction index of Transmission Fibers, A _effit is the useful area of Transmission Fibers.Increase the useful area of Transmission Fibers, the nonlinear effect in optical fiber can be reduced.

At present, for the general single mode fiber of land transmission system circuit, its useful area is about 80um only ²left and right.And in the long haul transmission system of land, requiring higher to the useful area of optical fiber, general useful area is at 100um ²above.In order to reduce laying cost, reduce the use of repeater as much as possible, at repeatless transmission system, as undersea transmission system, the useful area of Transmission Fibers is preferably at 130um ²above.But, in the design of the refractive index profile of current large effective area fiber, obtain large useful area often through the diameter increasing the optical core layer being used for transmitting optical signal.Such scheme also exists certain design difficulty.On the one hand, the key property of the sandwich layer of optical fiber and the covering major decision optical fiber near it, and larger proportion is occupied in the cost of fiber manufacturing, if the radial dimension of design is excessive, the manufacturing cost of optical fiber will inevitably be improved, raise optical fiber price, by the obstacle becoming this type optical fiber and generally apply.On the other hand, compare general single mode fiber, the increase of optical fiber effective area, can bring the deterioration of some other parameter of optical fiber: such as, fiber cut off wavelength can increase, if cutoff wavelength is excessive, is difficult to the single mode ensureing optical fiber light signal in transmission wave band; In addition, if Refractive Index Profile of Optical designs improper, bending property, the isoparametric deterioration of dispersion can also be caused.

The optic fibre characteristic of another kind of restriction long distance Large Copacity transmission is decayed exactly, the decay of the G.652.D optical fiber of current routine is generally at 0.20dB/km, laser energy is reducing gradually after long range propagation, so need to adopt the form of relaying again to amplify signal.And cost that is relative and optical fiber cable, relay station relevant device and maintenance cost, in more than 70% of whole chain-circuit system, if so relate to a kind of low decay or ultralow attenuating fiber, just can effectively be extended transmission distance, and reduce and build and maintenance cost.Through correlation computations, if the decay of optical fiber is reduced to 0.16dB/km from 0.20, the construction cost of whole link totally will reduce about 30%.

In sum, a kind of ultralow attenuation large effective area optical fiber of development and Design becomes an important topic of optical fiber fabrication arts.Document US2010022533 proposes a kind of design of large effective area fiber, in order to obtain lower Rayleigh coefficient, it adopts the design of pure silicon core, does not carry out the codope of germanium and fluorine in the core, and its design adopts the silicon dioxide mixing fluorine as surrounding layer.For the design of this pure silicon core, it requires that inside of optical fibre must carry out complicated viscosity coupling, and requires in drawing process, adopt extremely low speed, and the decay avoiding high-speed wire-drawing to cause the defect of inside of optical fibre to cause increases, manufacturing process and complexity thereof.

Document EP2312350 proposes a kind of large effective area fiber design of non-pure silicon core design, it adopts stepped sagging cladding structure design, and have a kind of design to adopt pure silicon dioxide surrounding layer structure, correlated performance can reach large effective area fiber G.654.B with the requirement of D.But the clad section maximum radius of Fluorin doped is 36 μm in its design, although can ensure that the cutoff wavelength of optical fiber is less than or equal to 1530nm, but be subject to the impact of its less Fluorin doped radius, the microcosmic of optical fiber and macrobending degradation, so in optical fiber cabling process, decay can be caused to increase, also not mentioned relevant bending property in its document.

Document CN10232392A describes a kind of optical fiber with more large effective area.Although the useful area of the described optical fiber of this invention reaches 150 μm ²above, but mix the sandwich layer design of mode altogether because of the germanium and fluorine that have employed routine, and realized by the performance index sacrificing cutoff wavelength.It allows cable cut-off wavelength at more than 1450nm, and in embodiment described in it, cabled cutoff wavelength even reaches more than 1800nm.In the middle of practical application, too high cutoff wavelength is difficult to ensure that optical fiber is ended in application band, just cannot ensure that light signal is single mode when transmitting.Therefore, this type optical fiber may face a series of practical problems in the application.In addition, in the embodiment cited by this invention, sink cladding outer diameter R ₃minimum is 16.3 μm, bigger than normal equally to some extent.This invention does not have to obtain optimum combination in optical fiber parameter (e.g., useful area, cutoff wavelength etc.) and fiber manufacturing cost.

From analysis above, we can find, there is the feasibility using non-pure silicon core and part Fluorin doped covering to carry out ultralow attenuating fiber technological design.But being subject to the impact of fibre-optic waveguide design limiting factor, if use pure silicon dioxide as outsourcing layer, how under such design, controlling the optical parametric of optical fiber, is our facing challenges.

Because if use and there is no the pure silicon dioxide of Fluorin doped as outsourcing layer, 3 problems can be faced.

The first, suppress basic mode cut-off: fibre-optic waveguide design in, outsourcing layer and core material refractive index difference too little, optical fiber basic mode can be caused to reveal, thus affect the decay of optical fiber.So adopt the non-ultralow attenuation large effective area optical fiber mixing the design of F outsourcing layer, because relative to traditional fiber, sandwich layer diameter is larger, just in surrounding layer and sandwich layer centre position, must be designed by rational fibre profile, suppresses basic mode to be revealed.

Generally traditional large effective area fiber all adopts single sagging cladding structure to optimize the waveguide of fiber glass part.Fundamental purpose is, is first to utilize structure of sinking to optimize MFD, and obtain larger useful area, this is method the most frequently used in optical design; Secondly be exactly because the sandwich layer diameter of large effective area fiber is general larger, thus cause the bending property of optical fiber poor, so utilize the cladding structure that sink to optimize the bending property of optical fiber.

Single sagging cladding structure Design and manufacture is relatively simple, so common, especially the large effective area fiber of normal attenuation coefficient is very common in designing.If but in ultralow attenuation large effective area optical fiber design, especially adopt pure silicon dioxide material as in the ultralow attenuation large effective area optical fiber of surrounding layer, because the refractive index of sandwich layer is little with the refractive index difference of pure silicon dioxide surrounding layer, and the sandwich layer diameter of large effective area fiber design is general all very large, the basic mode of having a headache most in just more easily causing fibre-optic waveguide to design is revealed, and causes optical fiber long wavelength to decay exception.And conventional solution, the cutoff wavelength of optical fiber can be caused again to exceed standard as increased the methods such as the volume of single sagging covering, so find a kind of blanket design method of better sinking, be also the emphasis realizing the design of ultralow attenuation large effective area optical fiber.

The second, consider viscosity coupling: if do not do any viscosity optimal design in outsourcing layer, its viscosity and inner cladding and sandwich layer viscosity gradient mismatch, also can cause the problems such as the defect of interface location and virtual temperature rising, thus increase optical fiber attenuation.Utilize single sagging cladding structure or two sagging cladding structure, while realizing fibre-optic waveguide optimization, utilize the difference of different structure doping of sinking, be more conducive to fibre profile viscosity matched design.In brief, if do not adopt sagging blanket design, so the viscosity design of inner cladding segment just only has a gradient; Adopt single sagging cladding structure, just can increase a gradient; Adopt two sagging cladding structure, be just equivalent to increase by three gradients (two sagging covering position doping are different, and the position of sinking between covering and sagging covering also can use the design of special viscosity).

3rd, consider optical cross-sectional coupling: if use pure silicon dioxide glass as outsourcing layer, when considering to be responsible for viscosity matched design, just define the concentration of various piece doping, and meet the parameter request of G652 or G654 optical fiber in order to the optical parametric demonstrate,proving optical fiber, both ensured the MFD of optical fiber, dispersion and bending property meet standard-required, and optical cross-sectional designs to require again us to consider.This just requires that we are when carrying out viscosity design, consider the optical design of optical fiber, add the difficulty that technique realizes.

Document US8515231B2 proposes a kind of single-mode fiber of two sagging cladding structure, but the design that its plug high concentration Ge adopted adulterates, and sandwich layer diameter is less, so can not reach ultralow fade performance, and useful area is significantly less than 100 μm ², the nonlinear effect of optical fiber can not be suppressed.

Summary of the invention

Be below definition and the explanation of some terms related in the present invention:

Relative index of refraction Δ n _i:

Count from fiber core axis, according to the change of refractive index, that layer be defined as near axis is core layer, and outermost layer and the pure silicon dioxide layer of optical fiber are defined as optical fiber jacket.

Optical fiber each layer relative index of refraction Δ i is defined by following equation:

$\mathrm{\Δ}i=\frac{n_i-n_c}{n_c}\×100\%$

Wherein n _ifor the refractive index of fibre core, and n _cfor outermost cladding index, namely do not carry out the refractive index of the pure silicon dioxide of Ge or F doping.

The relative index of refraction contribution amount Δ Ge that fiber core layer Ge adulterates is defined by following equation,

$\mathrm{\Δ}Ge=\frac{n_{Ge}-n_c}{n_c}\×100\%$

Wherein n _gefor supposing the Ge alloy of fibre core, not having in the pure silicon dioxide of other alloys being doped to, causing the variable quantity of silica glass refractive index, wherein n _cfor outermost cladding index, namely do not carry out the refractive index of the pure silicon dioxide of Ge or F doping.

The useful area A of optical fiber _eff.:

$A_{\mathrm{eff}}=2\mathrm{\π}\frac{({{\∫}_0^{\mathrm{\∞}}{E}^{2}rdr)}^2}{{\∫}_0^{\mathrm{\∞}}{E}^{4}rdr}$

Wherein, E is and propagates relevant electric field, and R is the distance that axle center arrives between Electric Field Distribution point.

Cable cut-off wavelength λ _cc:

Define in IEC (International Electrotechnical Commission) standard 60793-1-44: cable cut-off wavelength λ _ccthat light signal have propagated 22 meters of wavelength not being re-used as single mode signal afterwards and carrying out propagating in a fiber.Need by the circle of optical fiber around a radius 14cm when testing, the circle of two radius 4cm obtains data.

Technical matters to be solved by this invention is intended to design a kind of single-mode fiber with the ultralow attenuation large effective area of lower optical fiber manufacturing cost, and its cabled cutoff wavelength is less than 1530nm, and has good bending loss, dispersion.

The technical scheme that the problem that the present invention is the above-mentioned proposition of solution adopts is: include sandwich layer and covering, it is characterized in that described core radius R ₁be 4.5 ~ 6.5 μm, sandwich layer refractive index contrast Δ 1 is-0.05% ~ 0.10%, sandwich layer from inside to outside coated inner cladding successively outward, first sagging inner cladding, middle inner cladding, the second sagging inner cladding, auxiliary surrounding layer and surrounding layer, the inner cladding diameter R of described optical fiber ₂be 8.5 ~ 14 μm, refractive index contrast Δ 2 is-0.35% ~-0.12%, the described first sagging inner cladding diameter R ₃be 13 ~ 22 μm, refractive index contrast Δ 3 is-0.7% ~-0.30%, middle inner cladding diameter R ₄be 14 ~ 23 μm, refractive index contrast Δ 4 is-0.40% ~-0.15%; Second sagging inner cladding diameter R ₅be 18 ~ 30 μm, refractive index contrast Δ 5 is-0.6% ~-0.25%; Described auxiliary surrounding layer radius R ₆be 35 ~ 50 μm, refractive index contrast Δ 6 is-0.55% ~-0.15%; Described surrounding layer is pure silicon dioxide glassy layer.

By such scheme, the sandwich layer of optical fiber is the silica glass layer that germanium and fluorine are mixed altogether, or for mixing the silica glass layer of germanium, and the Ge-doped relative index of refraction contribution amount Δ Ge of its center core layer is 0.02% ~ 0.10%.

By such scheme, middle inner cladding diameter is greater than the first sagging inner cladding diameter, and R ₄-R ₃>=1 μm.

By such scheme, described optical fiber is 100 ~ 145 μm at the useful area of 1550nm wavelength ², under optimum condition, be 120 ~ 140 μm ².

By such scheme, the cabled cutoff wavelength of described optical fiber is equal to or less than 1530nm.

By such scheme, the zero dispersion point of described optical fiber is less than or equal to 1300nm.

By such scheme, described optical fiber is equal to or less than 23ps/nm*km in the dispersion at wavelength 1550nm place, and described optical fiber is equal to or less than 27ps/nm*km in the dispersion at wavelength 1625nm place.

By such scheme, described optical fiber is equal to or less than 0.175dB/km in the attenuation at wavelength 1550nm place; 0.170dB/km is equal to or less than under optimum condition; Described optical fiber is equal to or less than 0.204dB/km in the attenuation at wavelength 1625nm place; 0.194dB/km is equal to or less than under optimum condition.

By such scheme, described optical fiber is equal to or less than 3dB/km at the microbending loss at wavelength 1700nm place.

By such scheme, described optical fiber is at wavelength 1550nm place, and the macrobending loss that R15mm bend radius 10 is enclosed is equal to or less than 0.25dB, and the macrobending loss that R10mm bend radius 1 is enclosed is equal to or less than 0.75dB.

Beneficial effect of the present invention is: 1, adopt the sandwich layer design of mixing germanium, reasonably devises the viscosity coupling of inside of optical fibre, reduces defect in fiber preparation, reduce the attenuation parameter of optical fiber.2, devise rational optical fiber Fluorin doped to sink structure, and by the appropriate design to each core layer section of optical fiber, optical fiber is had and is equal to or greater than 100 μm ²useful area, under better parameter area, can reach and be equal to or greater than 130 μm ², be even greater than 140 μm ²useful area.3, utilize two sagging cladding structure design, effectively inhibit basic mode to end problem, and the method utilizing high-order mode to be coupled, effectively reduce the cutoff wavelength of optical fiber.To ensure the single mode of this type optical fiber light signal in C-band transmission application, and to the bending loss of optical fiber, there is good improved action.4, outermost surrounding layer structure have employed the design of pure silicon dioxide, reduces Fluorin doped glass proportion in a fiber, thus reduces fiber manufacturing production cost.

Accompanying drawing explanation

Fig. 1 is the refractive index profile structure distribution figure of one embodiment of the invention.

Embodiment

Describe the present invention below in conjunction with embodiment.

Include sandwich layer and covering, described sandwich layer is the silica glass layer that germanium and fluorine are mixed altogether, or for mixing the silica glass layer of germanium, the outer from inside to outside coated inner cladding successively of sandwich layer, first sink inner cladding, middle inner cladding, second sagging inner cladding, auxiliary surrounding layer and surrounding layer.Surrounding layer normal diameter is 125 μm.

Table one be classified as the refractive index profile parameter of the preferred embodiment of the invention, wherein Δ Ge is the Ge-doped relative index of refraction contribution amount of sandwich layer.The light-transfer characteristic of table two corresponding to optical fiber described in table one.

The fibre profile parameter of table one, the embodiment of the present invention

The fiber optics of table two, the embodiment of the present invention and bending property parameter

Claims (10)

1. a single-mode fiber for ultralow attenuation large effective area, includes sandwich layer and covering, it is characterized in that described core radius R ₁be 4.5 ~ 6.5 μm, sandwich layer refractive index contrast Δ 1 is-0.05% ~ 0.10%, sandwich layer from inside to outside coated inner cladding successively outward, and first sink inner cladding, middle inner cladding, and second sink inner cladding, auxiliary surrounding layer and surrounding layer, described inner cladding diameter R ₂be 8.5 ~ 14 μm, refractive index contrast Δ 2 is-0.35% ~-0.12%, the described first sagging inner cladding diameter R ₃be 13 ~ 22 μm, refractive index contrast Δ 3 is-0.7% ~-0.30%, middle inner cladding diameter R ₄be 14 ~ 23 μm, refractive index contrast Δ 4 is-0.40% ~-0.15%; Second sagging inner cladding diameter R ₅be 18 ~ 30 μm, refractive index contrast Δ 5 is-0.6% ~-0.25%; Described auxiliary surrounding layer radius R ₆be 35 ~ 50 μm, refractive index contrast Δ 6 is-0.55% ~-0.15%; Described surrounding layer is pure silicon dioxide glassy layer.

2. by the single-mode fiber of ultralow attenuation large effective area according to claim 1, it is characterized in that the sandwich layer of described optical fiber is the silica glass layer that germanium and fluorine are mixed altogether, or for mixing the silica glass layer of germanium, the Ge-doped relative index of refraction contribution amount Δ Ge of its center core layer is 0.02% ~ 0.10%.

3., by the single-mode fiber of the ultralow attenuation large effective area described in claim 1 or 2, it is characterized in that middle inner cladding diameter is greater than the first sagging inner cladding diameter, and R ₄-R ₃>=1 μm.

4., by the single-mode fiber of the ultralow attenuation large effective area described in claim 1 or 2, it is characterized in that described optical fiber is 100 ~ 145 μm at the useful area of 1550nm wavelength ².

5., by the single-mode fiber of the ultralow attenuation large effective area described in claim 1 or 2, it is characterized in that the cabled cutoff wavelength of described optical fiber is equal to or less than 1530nm.

6., by the single-mode fiber of the ultralow attenuation large effective area described in claim 1 or 2, it is characterized in that the zero dispersion point of described optical fiber is less than or equal to 1300nm.

7. by the single-mode fiber of the ultralow attenuation large effective area described in claim 1 or 2, it is characterized in that described optical fiber is equal to or less than 23ps/nm*km in the dispersion at wavelength 1550nm place, described optical fiber is equal to or less than 27ps/nm*km in the dispersion at wavelength 1625nm place.

8. by the single-mode fiber of the ultralow attenuation large effective area described in claim 1 or 2, it is characterized in that described optical fiber is equal to or less than 0.175dB/km in the attenuation at wavelength 1550nm place, described optical fiber is equal to or less than 0.204dB/km in the attenuation at wavelength 1625nm place.

9., by the single-mode fiber of the ultralow attenuation large effective area described in claim 1 or 2, it is characterized in that described optical fiber is equal to or less than 3dB/km at the microbending loss at wavelength 1700nm place.

10. by the single-mode fiber of the ultralow attenuation large effective area described in claim 1 or 2, it is characterized in that described optical fiber is at wavelength 1550nm place, the macrobending loss that R15mm bend radius 10 is enclosed is equal to or less than 0.25dB, and the macrobending loss that R10mm bend radius 1 is enclosed is equal to or less than 0.75dB.