CN106371167A - High-bandwidth multi-mode fiber - Google Patents

Abstract

The invention relates to a high-bandwidth multi-mode fiber which comprises a core layer and a wrapping layer surrounding the core layer. The High-bandwidth multi-mode fiber is characterized in that a refractive index profile of the core layer is parabolic, the distribution index alpha ranges from 1.9 to 2.2, the radius R1 of the core layer ranges from 23 to 27 micron, the maximal relative refractive index difference delta1 of the central position of the core layer ranges from 0.9% to 1.2%, the wrapping layer comprises an inner wrapping layer, a recessed wrapping layer and an outer wrapping layer from inside to outside successively, the radius of the inner wrapping layer is R2, the single-side radial width (R2-R1) ranges from 1 to 3 micron, the relative refractive index difference delta2 ranges from -0.05 to 0.05%, the radius of the recessed wrapping layer is R3, the single-side radial width (R3-R2) ranges from 4 to 8 micron, the relative refractive index difference delta3 ranges from 0.7 to -0.3%, and the outer wrapping layer is a pure silica glass layer. According to the invention, the bandwidth performance of the fiber is further improved via special material component design and waveguide structure optimized design of the core layer of the fiber.

Description

A kind of high-bandwidth multi-mode fiber

Technical field

The present invention relates to a kind of multimode fibre with high bandwidth performance, belong to technical field of photo communication.

Background technology

Multimode fibre is with its less expensive system cost advantage, and is easy to the feature continuing, in short-distance transmission network Widely use, such as in lan LAN.With the continuous growth to network capacity requirements for the user, high-property transmission network is to multimode Bandwidth of an optical fiber proposes higher requirement.

In order to obtain the high-bandwidth multi-mode fiber with good stability, Refractive Index Profile of Optical, especially core refractive Rate section must be with anticipated shape accurately mate.Generally the sandwich layer design in preform mixes certain density germanium to realize The index distribution of desired fiber core layer.But preform is after high-temperature fusion draws and is cooled to optical fiber, in light Under the influence of fine internal residual stress, index distribution can be distorted.Thus manage to reduce remaining answering in optical fiber production process The impact of power refractive index distribution is critically important.In glass network structure, dopant such as germanium, fluorine, chlorine plasma are formed with network Presented in body, intermediate or modified body, destroy the globality of legacy network structure, the viscous of glass can be reduced at high temperature Degree.Dopant ion concentration directly affects the high temperature viscosity of optical fiber.The amount of multimode fibre sandwich layer center doped germanium is more than sandwich layer edge The high temperature viscosity mismatch mixed germanium amount, lead to fiber optic materials component, exacerbate the formation of fiber core layer residual stress.

Chinese patent cn102654602 describes a kind of single-mode optics by method in pipe or the outer method alkali doped of pipe Fibre, reduces optical fiber attenuation by the control of sandwich layer and clad doped component and doping content difference.Patent cn 103030269 carries Go out the technique being combined with ovd and vad and prepare the multimode fibre mixing chlorine, but do not relate to fluorine doped and specific dopant Concentration value.

Content of the invention

The technical problem to be solved is to provide a kind of core material for the deficiency that above-mentioned prior art exists Rationally, structural design optimization is it is easy to the high-bandwidth multi-mode fiber of technology controlling and process for coupling.

The core refractive rate section of multimode graded-index optical fiber meets following power exponential function and is distributed:

$\begin{array}{cc}{n}^2\left(r\right)=n_1^2\&lsqb;1-2{\mathrm{\&delta;}}_0{\left(\frac{r}{a}\right)}^{\mathrm{\&alpha;}}\&rsqb;& r<a\end{array}$

Wherein, n₁Refractive index for optical fiber axle center；R is the distance leaving optical fiber axle center；A is optical fiber core radius；α is distribution Index；δ₀Refractive index for core centre opposed cladding layers.

Relative index of refraction is δ_i:

δ_i%=[(n_i ²-n₀ ²)/2n_i ²] × 100%,

Wherein, n_iIt is the refractive index apart from core centre i position；n₀For the minimum refractive index of fiber core layer, generally also light The refractive index of fine covering.

The present invention by solving the problems, such as adopted technical scheme set forth above is: includes sandwich layer and the bag around sandwich layer It is characterised in that described core refractive rate section parabolically shape, profile exponent α is 1.9～2.2 to layer, the radius r1 of sandwich layer For 23～27 μm, sandwich layer centre bit maximum relative refractive index difference δ 1 is 0.9%～1.2%, and described covering is from inside to outside successively For inner cladding, sink covering and surrounding layer, and the radius of described inner cladding is r2, and monolateral radial width (r2-r1) is 1～3 μm, Refractive index contrast δ 2 is -0.05～0.05%；The radius of described sagging covering is r3, and monolateral radial width (r3-r2) is 4～8 μm, refractive index contrast δ 3 is -0.7～-0.3%；Described surrounding layer is pure silicon dioxide glassy layer.

The silica glass layer being co-doped with for germanium fluorine chlorine ge/f/cl by such scheme, described sandwich layer, wherein, in sandwich layer Ge-doped amount is successively decreased along radial direction by mass, and Fluorin doped amount is incremented by or impartial, chlorine doping along radial direction by mass It is incremented by or impartial along radial direction by mass.

By such scheme, doping c when sandwich layer margin location doping when described Fluorin doped amount is incremented by or equalization_f2For 3000～20000ppm, more excellent for 5000～12300ppm.

By such scheme, sandwich layer margin location Fluorin doped amount c when described Fluorin doped amount is incremented by_f2Mix with sandwich layer centre bit fluorine Miscellaneous amount c_f1Ratio c_f2/c_f1For 5～40.

By such scheme, doping c when sandwich layer margin location doping when described chlorine doping is incremented by or equalization_cl2 For 200～8000ppm, more excellent for 1000～6000ppm.

By such scheme, sandwich layer margin location chlorine doping c when described chlorine doping is incremented by_cl2With sandwich layer centre bit chlorine Doping c_cl1Ratio c_cl2/c_cl1For 1.5～15.

By such scheme, c in described sandwich layer_f2+c_cl2More than 6000ppm, more excellent for 8000～15000ppm.

By such scheme, the numerical aperture of described optical fiber is 0.185～0.215.

By such scheme, described optical fiber has 3500mhz-km or 3500mhz-km band above in 850nm wavelength, 950nm wavelength has 1850mhz-km or 1850mhz-km band above, 1300nm wavelength have 500mhz-km or 500mhz-km band above.

By such scheme, described optical fiber has effective mould of 4700mhz-km or more than 4700mhz-km in 850nm wavelength Formula bandwidth (emb), has the effective model bandwidth (emb) of 2470mhz-km or more than 2470mhz-km in 953nm wavelength.

By such scheme, described optical fiber, at 850nm wavelength, is added with the bending that 7.5 millimeters of bending radius lead to around 2 circles Loss is less than 0.2db；At 1300nm wavelength, it is less than with the bending added losses that 7.5 millimeters of bending radius lead to around 2 circles 0.5db.

The technical scheme of methods for optical fiber manufacture of the present invention is: using pure quartz glass tube as substrate bushing pipe, using pcvd Or mcvd technique prepares sandwich layer；In reacting gas Silicon chloride. (sicl₄) and oxygen (o₂) in, it is passed through germanium tetrachloride (gecl₄) enter Row is Ge-doped, is passed through fluoro-gas and carries out fluorine (f) doping, is passed through chloride gas and carries out chlorine (cl) doping, by microwave or hydrogen The heating sources such as oxygen flame promote the mixed gas in bushing pipe that chemical reaction occurs, and are finally deposited in bushing pipe in the form of glass Wall；During being somebody's turn to do, in control bushing pipe, mixture pressure is in 10～18mbar；Doping according to described fibre-optic waveguide structure will Ask, successively change the flow of each component gas and reaction condition parameter in mixed gas, successively sink to center from the edge of sandwich layer Long-pending；After the completion of deposition, with electric furnace, post-depositional bushing pipe collapsing is become solid mandrel；Using the pipe external sediment work such as ovd or vad Skill is sequentially depositing out fluorine-containing sagging covering and pure quartz glass surrounding layer, prepared prefabricated rods；Or with fluorine doped glass pipe as sleeve pipe, Carry out secondary collapsing with solid mandrel, gained solid bar is combined into rit (rod in pure quartz glass trocar sheath again after combining Tube) prefabricated rods；Prefabricated rods are placed on fiber drawing tower and are drawn into optical fiber, two-layer ultra-violet curing inside and outside optical fiber surface coating Polypropylene acid resin.

Another technical scheme of methods for optical fiber manufacture of the present invention is: using pure quartz glass tube as substrate bushing pipe, makes Prepare sandwich layer, inner cladding and sagging covering with pcvd or mcvd technique；In reacting gas Silicon chloride. (sicl₄) and oxygen (o₂) In, it is passed through fluoro-gas and carries out fluorine (f) doping, first in the sagging covering of bushing pipe inwall deposition fluorine doped；Redeposited inner cladding；Again to It is passed through germanium tetrachloride (gecl in reacting gas₄), carry out Ge-doped, be passed through fluoro-gas and carry out fluorine (f) doping, be passed through chloride Gas carries out chlorine (cl) doping, goes out sandwich layer from edge to the center layer by layer deposition of sandwich layer；During being somebody's turn to do, control gaseous mixture in bushing pipe Body pressure is in 10～18mbar；Doping according to described fibre-optic waveguide structure requires, and successively changes each component gas in mixed gas The flow of body and reaction condition parameter；After the completion of deposition, with electric furnace, post-depositional bushing pipe collapsing is become solid mandrel；With pure Quartz glass is obtained rit prefabricated rods for sleeve pipe；Prefabricated rods are placed on fiber drawing tower and are drawn into optical fiber, in optical fiber surface coating The polypropylene acid resin of inside and outside two-layer ultra-violet curing.

The beneficial effects of the present invention is: 1, pass through the special material design of components of fiber core layer, common using germanium, fluorine, chlorine The mode mixed, improves total doping content of sandwich layer edge fluorine and chlorine so as to be higher than the fluorine of sandwich layer core, chlorine doping content, Core material high temperature viscosity is tried one's best mate, can reduce between sandwich layer marginal portion and core in terms of glass viscosity Difference so that the fiber core layer residual stress during prefabricated stick drawn wire is reduced, make the folding of fiber core layer gradation type Penetrate that rate distribution is precisely controlled, core refractive rate section and anticipated shape accurately mate, thus realize fiber bandwidth performance Lifting.2nd, pass through sedimentation such as pcvd and mcvd preparation technology in pipe and just can preferably realize the distribution of core refractive rate and dopant Component and the precise control of concentration.3rd, appropriate design waveguiding structure, waveguiding structure is further optimized, and so that bandwidth performance is entered One step improves.

Brief description

Fig. 1 is the refractive index profile schematic diagram of one embodiment of the invention.

Fig. 2 is a kind of doping component distribution schematic diagram of fiber core layer of the present invention.

Fig. 3 is another kind of doping component distribution schematic diagram of fiber core layer of the present invention.

Fig. 4 is the third doping component distribution schematic diagram of fiber core layer of the present invention.

Fig. 5 is a kind of doping component distribution schematic diagram of comparative example fiber core layer.

Specific embodiment

The present invention includes sandwich layer and the covering around sandwich layer, described core refractive rate section parabolically shape, and distribution refers to Number is α, and the radius of sandwich layer is r1, and sandwich layer centre bit maximum relative refractive index difference is δ 1；Described covering is followed successively by from inside to outside Inner cladding, sagging covering and surrounding layer, the radius of described inner cladding is r2, and monolateral radial width is (r2-r1), relative Rate difference is δ 2；The radius of described sagging covering is r3, and monolateral radial width is (r3-r2), and refractive index contrast is δ 3；Institute The surrounding layer stated is pure silicon dioxide glassy layer.The silica glass layer that described sandwich layer is co-doped with for germanium fluorine chlorine ge/f/cl, its In, in sandwich layer, Ge-doped amount is successively decreased along radial direction by mass, and Fluorin doped amount is incremented by or impartial along radial direction by mass, Chlorine doping is incremented by or impartial along radial direction by mass.

3 embodiments and 1 comparative example are given below, the present invention is further illustrated.Embodiment and comparative example light The core structure parameter of fibre, sandwich layer doping content and Specifeca tion speeification are as shown in table 1.

Embodiment 1, fiber optic materials adopt pcvd technique to be obtained, and when starting deposition of core layer, open and control germanium tetrachloride gas The effusion meter of flow, controls germanium tetrachloride flow to be gradually increased according to specific distribution curve by software.Open two points simultaneously Not Kong Zhi fluoro-gas and chlorine-containing gas flow effusion meter, from during edge to the center layer by layer deposition of sandwich layer, keep Chlorine-containing gas flow aperture is constant, and is gradually reduced fluoro-gas flow aperture, and keeps fluoro-gas flow aperture linearly to become Change.

Embodiment 2, fiber optic materials adopt pcvd technique to be obtained, and when starting deposition of core layer, open and control germanium tetrachloride gas The effusion meter of flow, controls germanium tetrachloride flow to be gradually increased according to specific distribution curve by software.Open two points simultaneously Not Kong Zhi fluoro-gas and chlorine-containing gas flow effusion meter, from during edge to the center layer by layer deposition of sandwich layer, keep Fluoro-gas flow aperture is constant, and is gradually reduced chlorine-containing gas flow aperture, by software control fluoro-gas flow according to Doping design needs and change.

Embodiment 3, fiber optic materials adopt pcvd technique to be obtained, and when starting deposition of core layer, open and control germanium tetrachloride gas The effusion meter of flow, controls germanium tetrachloride flow to be gradually increased according to specific distribution curve by software.Open two points simultaneously Not Kong Zhi fluoro-gas and chlorine-containing gas flow effusion meter, from during edge to the center layer by layer deposition of sandwich layer, gradually Reduce fluoro-gas flow aperture, be gradually reduced chlorine-containing gas flow aperture, control gas flow to set according to doping by software Meter needs and change.

Comparative example 1, fiber optic materials adopt mcvd technique to be obtained, and when starting deposition of core layer, open and control germanium tetrachloride gas The effusion meter of flow, controls germanium tetrachloride flow to be gradually increased according to specific distribution curve by software.Open two points simultaneously Not Kong Zhi fluoro-gas and chlorine-containing gas flow effusion meter, from during edge to the center layer by layer deposition of sandwich layer, keep Chlorine-containing gas flow aperture is constant, keeps fluoro-gas flow aperture constant.

Table 1: the core structure parameter of optical fiber, sandwich layer doping content and Specifeca tion speeification

Claims (9)

1. a kind of high-bandwidth multi-mode fiber, including sandwich layer and around sandwich layer covering it is characterised in that described core refractive rate Section parabolically shape, profile exponent α is 1.9～2.2, and the radius r1 of sandwich layer is 23～27 μm, and sandwich layer centre bit is maximum relatively Refractivity δ 1 is 0.9%～1.2%, and described covering is followed successively by inner cladding from inside to outside, sink covering and surrounding layer, institute The radius of the inner cladding stated be r2, monolateral radial width (r2-r1) be 1～3 μm, refractive index contrast δ 2 be -0.05～ 0.05%；The radius of described sagging covering is r3, and monolateral radial width (r3-r2) is 4～8 μm, refractive index contrast δ 3 For -0.7～-0.3%；Described surrounding layer is pure silicon dioxide glassy layer.

2. the high-bandwidth multi-mode fiber as described in claim 1 is it is characterised in that described sandwich layer is co-doped with for germanium fluorine chlorine ge/f/cl Silica glass layer, wherein, in sandwich layer, Ge-doped amount is successively decreased along radial direction by mass, Fluorin doped amount edge by mass Radial direction is incremented by or impartial, and chlorine doping is incremented by or impartial along radial direction by mass.

3. the high-bandwidth multi-mode fiber as described in claim 2 is it is characterised in that sandwich layer side when described Fluorin doped amount is incremented by Doping c when edge position doping or equalization_f2For 3000～20000ppm.

4. the high-bandwidth multi-mode fiber as described in claim 3 is it is characterised in that sandwich layer side when described Fluorin doped amount is incremented by Edge position Fluorin doped amount c_f2With sandwich layer centre bit Fluorin doped amount c_f1Ratio c_f2/c_f1For 5～40.

5. the high-bandwidth multi-mode fiber as described in claim 3 is it is characterised in that sandwich layer side when described chlorine doping is incremented by Doping c when edge position doping or equalization_cl2For 200～8000ppm.

6. the high-bandwidth multi-mode fiber as described in claim 5 is it is characterised in that sandwich layer side when described chlorine doping is incremented by Edge position chlorine doping c_cl2With sandwich layer centre bit chlorine doping c_cl1Ratio c_cl2/c_cl1For 1.5～15.

7. the high-bandwidth multi-mode fiber as described in claim 5 is it is characterised in that c in described sandwich layer_f2+c_cl2More than 6000ppm.

8. the high-bandwidth multi-mode fiber as described in claim 1 or 2 is it is characterised in that described optical fiber has in 850nm wavelength 3500mhz-km or 3500mhz-km band above, has 1850mhz-km or 1850mhz-km band above in 950nm wavelength, In 1300nm wavelength, there is 500mhz-km or 500mhz-km band above.

9. the high-bandwidth multi-mode fiber as described in claim 1 or 2 is it is characterised in that described optical fiber has in 850nm wavelength The effective model bandwidth of 4700mhz-km or more than 4700mhz-km, has 2470mhz-km or 2470mhz- in 953nm wavelength The effective model bandwidth of more than km.