CN105866879A - Ultralow-attenuation large-effective-area single mode fiber - Google Patents

Abstract

The invention relates to an ultralow-attenuation large-effective-area single mode fiber, comprising a core layer and a cover layer covering and winding the core layer. The ultralow attenuation large-effective-area single mode fiber is characterized in that the radius r1 of the core layer is 5-6.5 microns, and the relative index of refraction delta n1 is 0.02-0.14%; the core layer is a chlorine-doped silicon dioxide glass layer, and the content of chlorine in the core layer is 0.4-2 wt%; the cover layer is composed of an inner cover layer, a sunken inner cover layer, an auxiliary outer cover layer and an outer cover layer, which sequentially cover and wind the core layer from inside to outside; the radius r2 of the inner cover layer is 9-14 microns, and the relative index of refraction delta n2 is smaller than or equal to -0.18%; the radius r3 of the sunken inner cover layer is 12-20 microns, and the relative index of refraction delta n3 is smaller than or equal to -0.40%; the radius r4 of the auxiliary outer cover layer is 35-50 microns, and the relative index of refraction delta n4 is smaller than or equal to -0.18%; the outer cover layer is a pure silicon dioxide glass outer cover layer. The ultralow attenuation large-effective-area single mode fiber has low attenuation, the core layer and the cover layer are arranged reasonably, the viscosity is matched excellently, and the manufacturing process is simple.

Description

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

Technical field

The present invention relates to optical communication field, be specifically related to a kind of ultralow attenuation large effective area single-mode fiber.

Background technology

Optical fiber fabrication arts focus is to prepare ultralow decay novel single-mode fiber product at present, so finding a kind of effective method Reduce fiber attenuation coefficient, control manufacturing cost, for fiber manufacturing enterprise, be all the hugest challenge.It is main Difficulty is following three points: one, how to reduce decay: method currently mainly is to reduce the rayleigh scattering coefficient of optical fiber；Its Two, while obtaining ultralow attenuation quotient, need to ensure that each optical parametric of optical fiber meets ITU-T standard, refer mainly to MFD, Dispersion, cutoff wavelength and bending property control in the range of standard-required: i.e. while ensureing the ultralow fade performance of optical fiber, its He must control in respective range by optical parametric；Its three, optic fibre manufacture process is the most controlled, do not dramatically increase fiber manufacturing become This.

For three above difficulty, first for the decay how reducing optical fiber.For silica fibre, at 600nm-1600nm Decay mostly come from Rayleigh scattering, by the attenuation alpha caused by Rayleigh scattering_RCan be calculated by following formula:

${\mathrm{\α}}_R=\frac{1}{{\mathrm{\λ}}^4}{\∫}_0^{+\mathrm{\∞}}R\left(r\right)P\left(r\right)rdr/{\∫}_0^{+\mathrm{\∞}}P\left(r\right)rdr=\frac{R}{{\mathrm{\λ}}^4}+B$

In formula, λ is wavelength (μm), and R is rayleigh scattering coefficient (dB/km/ μm⁴)；P is light intensity；When rayleigh scattering coefficient is true When recognizing, B is corresponding constant.As long as thus it is just available because of declining caused by Rayleigh scattering to determine rayleigh scattering coefficient R Subtract α_R(dB/km).On the one hand Rayleigh scattering causes due to density fluctuation, on the other hand causes due to fluctuation of concentration. Thus rayleigh scattering coefficient R is represented by:

R=R_d+R_c

In above formula, R_dAnd R_cRepresent the rayleigh scattering coefficient change caused by density fluctuation and fluctuation of concentration respectively.Wherein R_cFor the fluctuation of concentration factor, it is mainly affected by fiber glass part doping content, is used the fewest Ge and F in theory Or other doping, R_cThe least, this is also to use the design of pure silicon core, it is achieved the reason of ultralow fade performance.

It should be noted that arrive, rayleigh scattering coefficient also includes another one parameter R_d。R_dFictive temperature T with glass_FPhase Close, and change with structure change and the variations in temperature of glass.The fictive temperature T of glass_FIt is to characterize one physics of glass structure Parameter, is defined as from certain temperature T that ' structure that glass is quickly cooled to room temperature glass no longer adjusts and to reach certain poised state corresponding Temperature.Work as T ' > Tf (softening temperature of glass), owing to the viscosity of glass is less, glass structure is prone to adjust, thus each Moment glass is in poised state, therefore T_F=T '；Work as T ' < T_g(transition temperature of glass), owing to the viscosity of glass is relatively big, Glass structure is difficult to adjust, and the structural adjustment of glass lags behind variations in temperature, therefore T_F>T’；Work as T_g<T’<T_f(the softening of glass Temperature), it is more shorter that glass trends towards balancing the required time, the most relevant with the component of glass and rate of cooling, therefore T_F> T ' or T_F<T’。

Virtual temperature is in addition to having relation with the thermal history of fiber preparation, and virtual temperature is had by the component of fiber glass material Substantially and directly affect.Specifically, the material component viscosity to fiber glass material, thermal coefficient of expansion, cooling procedure The impact in relaxation time, directly decides the virtual temperature of optical fiber.It should be noted that because of ultralow attenuating fiber glass part It is generally divided into several part, such as typical sandwich layer, inner cladding and surrounding layer, or more complicated structure.So to some it Between material compositional difference need reasonably mate: first ensure optical fiber optical waveguide, second ensure glass wire drawing should After being become optical fiber by wire drawing under power effect, between each layer, there is no obvious defect, cause optical fiber attenuation abnormal.

As it has been described above, from the point of view of optical fiber preparation technology, reducing fiber attenuation coefficient has three kinds of methods: the first is to try to reduce core The doping of layer segment, reduces the concentration factor of fiber Rayleigh scattering.The second is to reduce drawing speed, increases optical fiber annealing process, Ensureing that preform, during wire drawing becomes optical fiber, slowly reduces temperature, thus reduces the virtual temperature of optical fiber, reduction declines Subtract.But this method significantly improves fiber manufacturing cost, and slowly annealing process is to the contribution of optical fiber attenuation the most largely Prepared thermal history by fiber glass material component and prefabricated rods to restrict, so making the effect reducing decay in this way limited. The third is the material component coupling of appropriate design inside of optical fibre, i.e. on the basis of few doping, need to be to fiber core layer, and inner cladding And the glass material of other positions carries out rational proportioning and not only ensures in drawing process, there is rational light each position of optical fiber Learning Profile Match, there are rational viscosity, thermal expansion, Stress match in each position of optical fiber to be ensured.Manufacturing ultralow declining at present During dim light fibre, it is more attention to be placed in the first and three kinds of methods.

When using in the industry the third method to manufacture ultralow attenuating fiber at present, a kind of main method is to use the design of pure silicon core.Pure The design of silicon core refers to not carry out in sandwich layer the doping of germanium or fluorine.As it has been described above, do not have germanium Fluorin doped can effectively reduce light Fine concentration factor, advantageously reduces fiber Rayleigh coefficient.But use pure silicon core design also give optical fiber optical waveguide design with And material profile design brings a lot of challenge.When using the design of pure silicon core, in order to ensure the total reflection of optical fiber, it is necessary to use phase The inner cladding that adulterates the F of relatively low-refraction mates, to ensure to keep between sandwich layer and inner cladding enough refractive index difference. But in this case, the sandwich layer of pure silicon core is if not done by rational design of material, and its viscosity is by of a relatively high, and simultaneously big The inner cladding segment viscosity of amount F doping is relatively low, causes optical fiber structure viscosity coupling unbalance, so that the optical fiber of pure silicon cored structure is empty Intend temperature to increase sharply, cause the R of optical fiber_dIncrease.The most not only balance out R_cReduce the benefit brought, more likely cause Optical fiber attenuation is reversely abnormal.

For solving this problem, it is proposed that add alkali species in the sandwich layer of optical fiber, utilize alkali metal ion to glass material Modification, optimize viscosity and the thermal coefficient of expansion of optical fiber, make the glass material of fiber core layer and inner cladding be mutually matched, from And effectively reduce the Rayleigh coefficient of optical fiber.Alkali-metal side is added in the core as document US20100195999A1 uses Method, is keeping in the case of fiber core layer pure silicon core, by change the viscosity of fiber core layer part and core structure relaxation time Between, solve the R that viscosity mismatch causes_dIncrease, thus the overall rayleigh scattering coefficient reducing optical fiber.Although this kind of method is permissible Effectively reduce optical fiber attenuation, but technique preparation complexity relatively, need point multiple batches of plug to be processed, and alkali metal is mixed The control of miscellaneous concentration requires high, and when using the design of pure silicon core, in order to mate the refractive index of pure silicon core, it is necessary to use Fluorin doped glass Glass is as surrounding layer.The viscosity of Fluorin doped glass is the least, and manufacturing cost is high, is unfavorable for preparing large-sized optical fiber prefabricating Rod and high-speed wire-drawing, so being not easy to prepare on a large scale.

Owing to the design of pure silicon core+pure fluorine surrounding layer exists all inconvenience, if a kind of pure silicon dioxide can be developed as surrounding layer The ultralow decay of material becomes an important topic of optical fiber fabrication arts.But use pure silicon dioxide is as outsourcing layer, right Realization in ultralow attenuating fiber has two important challenges to need to solve.First is the waveguide design of optical fiber.In order to ensure optical fiber Waveguide, we must assure that the single mode transport pattern of optical fiber does not leak.If with reference to the design of conventional fiber, Refractive index is carried out the most highly doped, then high dopant can cause the Rayleigh coefficient of optical fiber to increase, it is impossible to realizes ultralow declining at sandwich layer Subtract.If not using high dopant at sandwich layer, or using adulterant less, how to ensure waveguide and other optical parametrics of optical fiber Just become a significant challenge.As document CN201310394404 proposes the design of a kind of ultralow attenuating fiber, it use pure two The surrounding layer design of silicon oxide, but because it uses typical step cross-section structure, do not use inner cladding design of sinking excellent Change the bending of optical fiber, and its sandwich layer and inner cladding do not carry out material component optimization, it is possible that occur when causing prefabricated rods to prepare Viscosity mismatch, it is possible to find that its decay is all higher than 0.170dB/km and bent horizontal is relatively poor.

Document CN201510359450.4 proposes ultralow attenuating fiber section and the design of material of a kind of non-pure silicon core.It utilizes core The a small amount of germanium fluorine of layer is co-doped with mating the Fluorin doped glass of inner cladding, optimizes the design of components of material, reduces light to a certain extent Fine rayleigh scattering coefficient；Utilize relatively low sagging inner cladding and auxiliary inner wrap material, it is achieved that the single mode transport of optical fiber； Make use of sandwich layer with the viscosity between optical fiber various piece and thermal stress, the difference of the coefficient of expansion, it is achieved that relatively low density fluctuation, Decrease the defect between interface.It should be noted that and the outsourcing layer of this design contains a certain amount of metal ion, from And it is integrally improved the viscosity of surrounding layer, and reducing the refractive index of outsourcing layer, this contributes to realizing material to a certain extent and glues Degree and the matched design of stress, but too increase the density fluctuation coefficient of optical fiber integral material.It was noted that the decay of this design Level is all higher than 0.162dB/km, increases as do not solved the fluorin-doped concentration factor caused of the germanium of sandwich layer and continues to reduce core The viscosity of layer；And solving the surrounding layer viscosity higher mismatch with auxiliary inner cladding viscosity, the program is difficult to continue to reduce declining of optical fiber Subtract.

Summary of the invention

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

Ppm: millionth weight ratio；

Start to count from fiber core axis, according to the change of refractive index, be defined as the sandwich layer that layer is optical fiber near axis, The outermost layer of optical fiber does not i.e. have the pure silicon dioxide layer of germanium and Fluorin doped to be defined as optical fiber jacket.

Relative index of refraction Δ n_i:

Optical fiber each layer relative index of refraction Δ n_iDefined by below equation,

${\mathrm{\&Delta;n}}_i=\frac{n_i-n_c}{n_c}\&times;100\%$

Wherein n_iFor the absolute index of refraction of optical fiber ad-hoc location part, and n_cFor synthesizing the absolute index of refraction of pure quartz glass, the most do not enter The synthesis pure silicon dioxide absolute index of refraction of row Ge or F doping.

The effective area A of optical fiber_eff:

$A_{eff}=2\mathrm{\&pi;}\frac{{\left({\&Integral;}_0^{\mathrm{\&infin;}}{E}^{2}rdr\right)}^2}{{\&Integral;}_0^{\mathrm{\&infin;}}{E}^{4}rdr}$

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

Cable cut-off wavelength λ_cc:

Defined in IEC (International Electrotechnical Commission) standard 60793-1-44: cable cut-off wavelength λ_ccIt is that optical signal passes in a fiber It is not re-used as, after having broadcast 22 meters, the wavelength that single mode signal carries out propagating.Test time need to by optical fiber around a radius 14cm Circle, the circle of two radius 4cm obtains data.

The technical problem to be solved is that the deficiency existed for above-mentioned prior art provides a kind of ultralow decay the most effective Area single-mode optical fiber, it not only decays low, and core covering arranges rationally, and viscosity coupling is excellent, and processing technology is easy.

The present invention solves that the technical scheme that problem set forth above is used is: include sandwich layer and hold the covering of sandwich layer, its The core radius r1 being characterised by described is 5～6.5 μm, and relative index of refraction Δ n1 is 0.02～0.14%, and described sandwich layer is Mixing the silica glass layer of chlorine, in sandwich layer, the content of chlorine is 0.4-2wt% (percentage by weight), and described covering is by introversion Outer hold the inner cladding of sandwich layer, the inner cladding that sink, auxiliary surrounding layer and surrounding layer successively, described inner cladding diameter r2 be 9～ 14 μm, relative index of refraction Δ n2 is less than or equal to-0.18%, and described sagging inner cladding diameter r3 is 12～20 μm, relatively Refractive index n3 is less than or equal to-0.40%, and described auxiliary outsourcing cladding radius r4 is 35～50 μm, relative index of refraction Δ n4 Less than or equal to-0.18%, described surrounding layer is pure silicon dioxide glass overclad.

By such scheme, described inner cladding relative index of refraction Δ n2 is-0.18～-0.40%.

By such scheme, the described silica glass layer that sagging inner cladding is fluorine doped, relative index of refraction Δ n3 be-0.40～ -0.61%.

By such scheme, described auxiliary surrounding layer is the silica glass layer of fluorine doped, relative index of refraction Δ n4 be-0.18～ -0.47%.

By such scheme, described optical fiber effective area at 1550nm wavelength is 100～145 μm²。

By such scheme, described optical fiber attenuation quotient at 1550nm wavelength is less than or equal to 0.165dB/km, optimum condition Under, less than or equal to 0.160dB/km.

By such scheme, the cabled cutoff wavelength of described optical fiber equals 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, the dispersion at wavelength 1550nm of the described optical fiber equals to or less than 23ps/nm*km, and described optical fiber is at ripple Dispersion at long 1625nm equals to or less than 27ps/nm*km.

The present invention is based on following research: the chlorine doping carrying out high concentration in sandwich layer part can realize being similar to alkali metal ion pair The modification of glass material.At the fiber core layer position doping chloride ion more than 5000ppm, the refractive index of optical fiber can be improved, fall The viscosity of low optical fiber, accelerates the structural relaxation of glass.It is further noted that, the concentration factor of optical fiber is contributed by chlorine ion concentration Inconspicuous, so the suitable chlorine ion concentration improving sandwich layer glass material, in conjunction with the inner wrap material design of components of matched design, The attenuation quotient of optical fiber can be effectively reduced；So that the optimization of outsourcing layer component, it is more prone to control, it is not necessary to use Al and other metal ions increase the viscosity of outsourcing layer.That is: use the pure silicon core design of chlorine doping, reduce fiber core layer Viscosity；Inner cladding doping reasonable in design, the relaxation time of coupling sandwich layer；Utilize inner cladding design of sinking, optimize optical waveguide； Sandwich layer reasonable in design, inner cladding, sink inner cladding and auxiliary inner cladding Fluorin doped concentration solution inside of optical fibre viscosity coupling； Finally utilizing harder pure silicon dioxide surrounding layer structure to undertake the main drawing tensile force of optical fiber, what minimizing drawing optical fibers tension force caused should Power defect.

The beneficial effects of the present invention is: 1, by sandwich layer, and inner cladding and sagging inner cladding, assist surrounding layer, outsourcing Layer carries out different materials component and waveguiding structure design, optimizes the design of optical fiber various piece viscosity and fiber stress section, realizes The ultralow fade performance of single-mode fiber and have greatly little area；2, the pure silicon sandwich layer coupling pure silicon dioxide glass outsourcing of chlorine doping is used Layer decreases doping process and controls difficulty, reduces optical fiber fabrication cost；3, sandwich layer is the pure silicon sandwich layer of chlorine doping, reduces core Layer viscosity；By appropriate design sandwich layer and inner wrap material, reduce sandwich layer and inner cladding glass material is tied in fiber preparation Structure relaxation time mismatch, decreases boundary defect；4, in sandwich layer and surrounding layer centre position, designed by sagging surrounding layer, press down Basic mode processed cut-off problem, improves fibre-optic waveguide transmission conditions；5, drawing optical fibers tension force is undertaken by pure silicon dioxide surrounding layer structure, Reduce the interface location defect that stress causes.

Accompanying drawing explanation

Fig. 1 is the Refractive Index Profile of Optical schematic diagram of the present invention.

Detailed description of the invention

Describe the present invention below in conjunction with specific embodiment.

Optical fiber includes sandwich layer, inner cladding, the inner cladding that sink, auxiliary inner cladding and surrounding layer composition.Sandwich layer is by the titanium dioxide mixing chlorine Quartz silica glass forms；Inner cladding closely surrounds sandwich layer；Sagging inner cladding closely surrounds inner cladding, by fluorine doped silica quartz Glass forms；Sink inner cladding outer wrap auxiliary surrounding layer, and auxiliary surrounding layer is the silica glass layer of fluorine doped；Optical fiber prefabricating Rod outermost layer is made up of pure silicon dioxide glass, and surrounding layer radius is 62.5 μm.

The core material component of the be classified as preferred embodiment of the present invention of table 1, each several part refractive index profile parameter and the decay system of correspondence Number.

Table 1

Claims (10)

1. a ultralow attenuation large effective area single-mode fiber, includes sandwich layer and holds the covering of sandwich layer, it is characterised in that be described Core radius r1 be 5～6.5 μm, relative index of refraction Δ n1 is 0.02～0.14%, and described sandwich layer is the titanium dioxide mixing chlorine Silica glass layer, in sandwich layer, the content of chlorine is 0.4-2wt%, described covering be hold the most successively sandwich layer inner cladding, under Falling into inner cladding, auxiliary surrounding layer and surrounding layer, described inner cladding diameter r2 is 9～14 μm, and relative index of refraction Δ n2 is less than Or equal to-0.18%, described sagging inner cladding diameter r3 is 12～20 μm, relative index of refraction Δ n3 is less than or equal to-0.40%, Described auxiliary outsourcing cladding radius r4 is 35～50 μm, and relative index of refraction Δ n4 is less than or equal to-0.18%, described outsourcing Layer is pure silicon dioxide glass overclad.

2. the ultralow attenuation large effective area single-mode fiber as described in claim 1, it is characterised in that described inner cladding phase doubling Penetrating rate Δ n2 is-0.18～-0.40%.

3. the ultralow attenuation large effective area single-mode fiber as described in claim 1 or 2, it is characterised in that the described interior bag that sink Layer is the silica glass layer of fluorine doped, and relative index of refraction Δ n3 is-0.40～-0.61%.

4. the ultralow attenuation large effective area single-mode fiber as described in claim 1 or 2, it is characterised in that described auxiliary outsourcing Layer is the silica glass layer of fluorine doped, and relative index of refraction Δ n4 is-0.18～-0.47%.

5. the ultralow attenuation large effective area single-mode fiber as described in claim 1 or 2, it is characterised in that described optical fiber exists Effective area at 1550nm wavelength is 100～145 μm²。

6. the ultralow attenuation large effective area single-mode fiber as described in claim 1 or 2, it is characterised in that described optical fiber exists Attenuation quotient at 1550nm wavelength is less than or equal to 0.165dB/km.

7. the ultralow attenuation large effective area single-mode fiber as described in claim 1 or 2, it is characterised in that described optical fiber exists Attenuation quotient at 1550nm wavelength is less than or equal to 0.160dB/km.

8. the ultralow attenuation large effective area single-mode fiber as described in claim 1 or 2, it is characterised in that the stranding of described optical fiber Cutoff wavelength equals to or less than 1530nm.

9. the ultralow attenuation large effective area single-mode fiber as described in claim 1 or 2, it is characterised in that zero color of described optical fiber Scatterplot is less than or equal to 1300nm.

10. the ultralow attenuation large effective area single-mode fiber as described in claim 9, it is characterised in that described optical fiber is at wavelength Dispersion at 1550nm equals to or less than 23ps/nm*km, and the dispersion at wavelength 1625nm of the described optical fiber equals to or less than 27ps/nm*km。