The content of the invention
In view of this, it is necessary to provide a kind of optical fiber, it passes through rational optical fiber structure and designs, and the loss of optical fiber is entered one
Step is reduced, and is met simultaneously G.654 to mode field diameter, cutoff wavelength and the isoparametric requirement of bending loss.
The present invention provides a kind of cutoff wavelength displacement single-mode fiber, including sandwich layer, the inner cladding, the depression bag that coat successively
Layer, middle covering and surrounding layer, wherein:
The radius of the sandwich layer is R1, R1Scope be 5.5~8.5 μm, the refractive index of the sandwich layer is n1, the sandwich layer
The refringence of relatively described surrounding layer is △ n1, △ n1Scope be 0.1%~0.3%;
The radius of the inner cladding is R2, the thickness of the inner cladding is R2-R1, R2-R1Scope be 5~25 μm, it is described
The refractive index of inner cladding is n2, the refringence of the relatively described surrounding layer of the inner cladding is △ n2, △ n2Scope be -0.2%
~0%;
The radius of the depressed cladding is R3, the thickness of the depressed cladding is R3-R2, R3-R2Scope be 4.5~12 μ
M, the refractive index of the depressed cladding is n3, the refringence of the relatively described surrounding layer of the depressed cladding is △ n3, △ n3Model
Enclose is -0.45%~-0.25%;
The radius of the middle covering is R4, the thickness of the middle covering is R4-R3, R4-R3Scope be more than 10 μm, it is described
The refractive index of middle covering is n4, the refringence of the relatively described surrounding layer of middle covering is △ n4, △ n4Scope be △ n2~
0%;
The radius of the surrounding layer is R5, R5Scope be 60~65 μm, the refractive index of the surrounding layer is nc。
Further, the radius R of the surrounding layer5Representative value be 62.5 μm.
Further, effective area of the optical fiber under wavelength 1550nm is 100~170 μm2;Under wavelength 1550nm
Dispersion be more than 18ps/nm/km;Attenuation coefficient under wavelength 1550nm is less than 0.18dB/km;The cable cutoff of the optical fiber
Wavelength is less than 1530nm.
Further, the effective area of the optical fiber is 100~145 μm2When, under wavelength 1550nm, 30mm radiuses-
The macrobending loss of 100 circles is less than 0.05dB, and under wavelength 1625nm, the macrobending loss of the circle of 30mm radiuses -100 is less than 0.1dB.
Further, the effective area of the optical fiber is 145~170 μm2When, under wavelength 1550nm, 30mm radiuses-
The macrobending loss of 100 circles is less than 0.15dB, and under wavelength 1625nm, the macrobending loss of the circle of 30mm radiuses -100 is less than 0.3dB.
Further, the application wave-length coverage of the optical fiber is 1535~1625nm.
Further, the optical fiber is the low-loss single-mode optical fiber of cutoff wavelength displacement.
The optical fiber that optical fiber structure provided by the present invention is designed can not only meet G.654 the mode field diameter of optical fiber,
Cable cut-off wavelength λccWith the parameter request such as bending loss, and with the spy of low decay, large effective area and low bend loss
Point;The controllability of fiber cut off wavelength can be realized by the regulation to optical fiber structure (middle covering) refractive index simultaneously.
Specific embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, the technical scheme in the embodiment of the present invention is carried out clear, complete
Site preparation is described, it is clear that described embodiment is only a part of embodiment of the invention, rather than whole embodiments.It is based on
Embodiment in the present invention, it is every other that those of ordinary skill in the art are obtained under the premise of creative work is not made
Embodiment, belongs to the scope of protection of the invention.It is appreciated that accompanying drawing is only provided used with reference to explanation, not for this hair
It is bright to be any limitation as.The connection shown in accompanying drawing is only to be described for ease of clear, and does not limit connected mode.
It should be noted that when a part is considered as " connection " another part, it can be directly to another
Part may be simultaneously present part placed in the middle.Unless otherwise defined, all of technologies and scientific terms used here by the article with belong to
The implication that those skilled in the art of the invention are generally understood that is identical.Used in the description of the invention herein
Term is intended merely to describe the purpose of specific embodiment, it is not intended that in the limitation present invention.
Fig. 1 and Fig. 2 is refer to, the present embodiment provides a kind of optical fiber 10, and it can realize low-loss and large effective area.
In present embodiment, optical fiber 10 is G.654 single-mode fiber, its mode field diameter, cable cut-off wavelength λccWith the parameter such as bending loss
Meet the parameter and standard of G.654 optical fiber.Optical fiber 10 includes being located at the sandwich layer 11 of center, is coated on the outer surface of sandwich layer 11
Inner cladding 13, the depressed cladding 15 being coated on the outer surface of inner cladding 13, the middle covering being coated on the outer surface of depressed cladding 15
17 and the surrounding layer 19 that is coated on the outer surface of middle covering 17.As shown in figure 1, sandwich layer 11, inner cladding 13, depressed cladding 15, in
The cross-sectional view of covering 17 and surrounding layer 19 is five concentric circles.In the present embodiment, the increase of depressed cladding 15 is conducive to
The optimization of the bending loss of single-mode fiber 10;Surrounding layer 19 is typically made up of pure silicon dioxide.In other embodiment of the invention
In, surrounding layer 19 is alternatively the silica of other additional materials of light dope, such as silica of slight fluorine doped.
The radius of sandwich layer 11 is R1, the refractive index of sandwich layer 11 is n1, the refringence between sandwich layer 11 and surrounding layer 19 is △
n1, wherein, R1Scope be 5.5~8.5 μm, △ n1Scope be 0.1%~0.3%.Reflected between sandwich layer 11 and surrounding layer 19
The change of rate difference can be realized by adulterating germanium dioxide in sandwich layer 11.
The radius of inner cladding 13 is R2, the refractive index of inner cladding 13 is n2, the refractive index between inner cladding 13 and surrounding layer 19
Difference is △ n2, wherein, the thickness R of inner cladding 132-R1Scope be 5~25 μm, △ n2Scope be -0.2%~0%.
The radius of depressed cladding 15 is R3, the refractive index of depressed cladding 15 is n3, between depressed cladding 15 and surrounding layer 19
Refringence is △ n3, wherein, the thickness R of depressed cladding 153-R2Scope be 4.5~12 μm, △ n3Scope be -0.45%
~-0.25%.
The radius of middle covering 17 is R4, the refractive index of middle covering 17 is n4, the refractive index between middle covering 17 and surrounding layer 19
Difference is △ n4, wherein, the thickness R of middle covering 174-R3Scope be the △ n more than 10 μm4Scope be △ n2~0%.
The radius of surrounding layer 19 is R5, the refractive index of surrounding layer 19 is n5, the thickness of surrounding layer 19 is R5-R4, wherein, R5's
Scope is 60~65 μm, and its representative value is that 62.5 μm, the i.e. radius of optical fiber 10 are 60~65 μm, and its representative value is 62.5 μ
m。
Following table I shows the example of the structure design according to optical fiber of the present invention 10, and outer other of the scope of the invention set
The comparative example of meter.Wherein example 3, example 5, example 7 and example 8 are the examples according to structure design of the present invention, and example 1, example 2, example 4 and example 6 exist
Outside protection scope of the present invention and be to be compared given example.
Table I
Following table II shows the test value of the main performance of example shown in Table I and comparative example.The present invention before testing, example
The optical fiber of the description of 1 to example 8 under zero tension force after-combustion on the disk of a 420mm diameters, then using optical time domain reflectometer
(PK8000-OTDR) decay of the test optical fiber under each wavelength, to eliminate influence of the macrobending to attenuation test result.
Table II
Fig. 3 to Figure 10 is refer to, the different and superiority of each example and comparative example is analyzed in combination with Table I and Table II.Example 1
It is using axial vapor deposition method (VAD) or VAD and improved chemical vapor deposition (MCVD) fluorine doped to example 5 (Fig. 3 to Fig. 7)
Quartz socket tube mixing method makes the example of optical fiber.Example 1 and common G.652 optical fiber ((Δ n1+|Δn2|) about 0.35%) with class
As index distribution, be simplest fiber design be also the most frequently used G.654 optical fiber at present design, on the one hand it pass through
Increase the radius of sandwich layer 11 to increase effective area;On the other hand by reducing the refringence (Δ of sandwich layer 11 and inner cladding 13
n1+|Δn2| about 0.29%) increase effective area.Relative to the performance of G.652 optical fiber, the optical fiber of example 1 has relatively low decay system
Number and big mode field diameter, but due to being limited by cable cut-off wavelength and bending loss, between sandwich layer 11 and inner cladding 13
The incrementss of refringence optimization range and effective area are all very limited (nominal value of mode field diameter is typically smaller than 12.5 μm).
If necessary to further improve mode field diameter, except adjustment sandwich layer 11 and the refringence and sandwich layer diameter of inner cladding 13, also adopt
The bending loss of optical fiber is controlled with sunk structure.
Example 2 and example 1 have identical (Δ n1+|Δn2|) (about 0.29%).Further to reduce fibre loss, example 2 passes through
Reduce the doping reduction n of the germanium dioxide of sandwich layer 111, in order to keep mode field diameter constant, while reducing n2.Test result shows
Attenuation coefficient of the optical fiber of example 2 at 1550nm has somewhat declined, but cable cut-off wavelength is relatively low (1298nm).Although inner cladding
13 thickness is very big (about 22 μm), but bending loss is seriously deteriorated that (1550nm and 1625nm at, it is grand that 30mm radiuses -100 are enclosed
Curved loss is up to 0.27dB and 0.93dB respectively).
Example 3 with the addition of depressed cladding 15 and middle covering 17 on the basis of example 2, from Table II it can be seen that the optical fiber of example 3 it is curved
Song loss be significantly reduced (1550nm and 1625nm at, 30mm radiuses -100 circle macrobending loss respectively up to 0.01dB with
0.02dB), the attenuation coefficient and at 1550nm is relatively low, and cable cut-off wavelength is also significantly improved (1444nm).
Example 4 has identical n with example 2 and example 32.Optical fiber attenuation is further reduced simultaneously in order to increase mode field diameter, and example 4 has
Low-down Δ n1(0.12%), its (Δ n1+|Δn2|) it is about 0.2%.It is (i.e. recessed that the example employs traditional sunk structure
Fall into covering 15) reduce bending loss, but the data display sunk structure of Table II improves limited for the bending loss of great circle
(at 1550nm and 1625nm, the macrobending loss of the circle of 30mm radiuses -100 reaches 0.20dB and 0.39dB respectively);Simultaneously because Δ
n1Reduction, the cable cut-off wavelength of the optical fiber of example 4 is too low (1021nm), and the cable cut-off wavelength is difficult to adjust and controls.
It is not enough present in example 4 to solve, example 5 be with the addition of on the basis of example 4 in covering 17, from Table II it can be seen that example
5 bending loss that can further reduce optical fiber on the basis of relatively low decay (at 1550nm and 1625nm, 30mm radiuses-
The macrobending loss of 100 circles reaches 0.07dB and 0.16dB respectively), and cable cut-off wavelength meets G.654 standard.
Example 6 to example 8 (Fig. 8 to Figure 10) is to make optical fiber using MCVD techniques and fluorine-doped quartz sleeve pipe or pure quartz socket tube
Example.The optical fiber of comparative example 6 is further reducing the folding of sandwich layer 11 to the main performance test value and parameter of structure design of the optical fiber of example 8
Penetrate rate n1, reduce optical fiber attenuation on the premise of, simply use improvement of the depressed cladding 15 to bending loss be it is very limited amount of, only
There is increase to employ the design of middle covering 17, the bending loss of optical fiber can be just reduced within claimed range.The optical fiber of example 7 exists
Fiber attenuation coefficient at 1550nm is 0.176dB/km, and the macrobending loss of the circle of 30mm radiuses -100 is 0.02dB;In 1625nm
Place, fiber attenuation coefficient is 0.192dB/km, and the macrobending loss of the circle of 30mm radiuses -100 is 0.04dB.Comparative example 6 and example 7 and example
8, cable cut-off wavelength λcc1512nm and 1405nm are changed into from 1303nm, i.e., by cladding index n in regulation4, can be to optical fiber
Cutoff wavelength is changed and controls.
The knot of the center core layer 11 of optical fiber 10, inner cladding 13, depressed cladding 15, middle covering 17 and surrounding layer 19 that the present invention is provided
The characteristics of structure design has low decay, large effective area and low bend loss.Simultaneously sandwich layer 11, inner cladding 13, depressed cladding 15,
The parameter of middle covering 17 and surrounding layer 19 can realize following feature:The application wave-length coverage of optical fiber 10 is 1535nm to 1625nm;
Effective area is 100~170 μm under wavelength 1550nm2;Dispersion is more than 18ps/nm/km under wavelength 1550nm;In wavelength
Attenuation coefficient under 1550nm is less than 0.18dB/km.The cable cut-off wavelength of optical fiber 10 is less than 1530nm.
When the effective area scope of optical fiber 10 is 100~145 μm2, under wavelength 1550nm, it is grand that 30mm radiuses -100 are enclosed
Curved loss is less than 0.05dB, and under wavelength 1625nm, the macrobending loss of the circle of 30mm radiuses -100 is less than 0.1dB.When optical fiber 10
Effective area scope is 145~170 μm2, under wavelength 1550nm, the macrobending loss of the circle of 30mm radiuses -100 is less than 0.15dB,
Under wavelength 1625nm, the macrobending loss of the circle of 30mm radiuses -100 is less than 0.3dB.The optical fiber 10 that the present invention is provided is complied fully with
G.654 on mode field diameter, cable cut-off wavelength λ in standardccWith the requirement of bending loss, further reduce and decay and realize low
Bending loss and large effective area, meanwhile, the single-mode fiber 10 that the present invention is provided can be by the refractive index n of covering in regulation 174
Size, to realize change and control to fiber cut off wavelength.
The fibre-optical mandrel of the optical fiber 10 that the present invention is provided is applied to axial vapor deposition method (VAD), outside chemical gas phase and sinks
The various manufacture works such as area method (OVD), Plasma Enhanced Chemical Vapor Deposition (PECVD) (PCVD) and modified chemical vapor deposition process (MCVD) (MCVD)
Skill or hybrid technique.In the present embodiment, the manufacture craft of the fibre-optical mandrel can be using sedimentation in pipe, i.e., with silicon tetrachloride
As the raw material of silica, germanium tetrachloride as germanium dioxide raw material, ocratation, sulfur hexafluoride or perfluoroethane conduct
The raw material of fluorine doped, depressed cladding 15, inner cladding 13 and sandwich layer 11 are sequentially depositing in the quartzy base tube inner surface of fluorine doped, then in high temperature
It is lower by the deposition base tube collapsing into the plug, the now quartzy base tube of the quartzy base tube of the fluorine doped or the part fluorine doped
Covering 17 in formation.If the thickness of middle covering 17 is less than design load, can use in the side of the additional fluorine doped sleeve pipe of the fibre-optical mandrel
Formula realizes that now the fibre-optical mandrel and the fluorine doped sleeve pipe pass through sleeve pipe collapsing method integrator.Sedimentation is fitted in the pipe
For PCVD, MCVD or smelting furnace chemical vapour deposition technique (FCVD) manufacturing process.
In other embodiment of the invention, also the fibre-optical mandrel can be made using other manufacture crafts, such as mixed
Method, i.e., make the inner core rod of the fibre-optical mandrel first with VAD or OVD methods, and the inner core rod includes sandwich layer 11 and inner cladding 13;
In conjunction with PCVD, MCVD or FCVD method, using silicon tetrachloride as the raw material of silica, ocratation, sulfur hexafluoride or hexafluoro
Ethane as fluorine doped raw material, in fluorine-doped quartz pipe internal surface sedimentary depression covering 15;By the inner core rod and the fluorine doped stone
English pipe forms middle covering by sleeve pipe collapsing method integrator, now the fluorine-doped quartz pipe or part the fluorine-doped quartz pipe
17, if the thickness of middle covering 17 is less than design load, can be realized by the way of separately fluorine doped sleeve pipe is added outside the fibre-optical mandrel.Or
Other methods that can produce fluorine doped high purity quartz prepare depressed cladding 15 and middle covering 17, such as fluorine doped sleeve pipe or utilization OVD powder
Deposition combines fluorine doped sintering process in the inner core rod external sediment depressed cladding 15 and middle covering 17 etc..
After the fibre-optical mandrel of the single-mode fiber 10 completed by above method preparation is through survey calculation, the plug needed for obtaining is straight
Footpath and the thickness of surrounding layer 19, obtain the plug of goal standard, then melt contracting by quartz glass tube by being heat-treated extension, alignment
Or outside deposition, melt contracting method formed surrounding layer 19, finally by degassing etc. operation formed single-mode fiber 10 predispersed fiber
Rod processed.It should be understood that needing accurately to realize the △ n of design during the fibre-optical mandrel is made1、△n2、△n3、△
n4And the value of α, to ensure mode field diameter, the cable cut-off wavelength λ of single-mode fiber 10ccMeet G.654 standard with bending loss.
The single-mode fiber 10 that the present invention is provided can not only meet the G.654 mode field diameter of optical fiber, cable cut-off wavelength λcc
With the parameter request such as bending loss, and the characteristics of with low decay, large effective area and low bend loss;Simultaneously can be by right
The regulation of optical fiber structure refractive index, realizes the controllability of fiber cut off wavelength.The low damage of the cutoff wavelength displacement that the present invention is provided
Consumption single-mode fiber 10 can be applied to some high speed long distance optic transmission systems, including fibres submarine telecommunication, such as land and island, island
Communication system between small island and island, coastal cities;The geographical conditions such as circuit needs cross the desert, lake, marsh, forest are severe
Place, and geographical environment is complicated or the more severe place of weather etc.;And private communication along high-voltage electric power system.
In specification and claims of this application requirements, word "comprises/comprising" and word " have/including " and its deformation,
For specifying the presence of stated feature, numerical steps or part, but one or more of the other spy is not precluded the presence or addition of
Levy, numerical value, step, component or combinations thereof.
For clarity, some described in a single embodiment features of the present invention, can combine in single embodiment
In use.And, the various features of the invention described in single embodiment, it is also possible to individually or with any suitable shape
Formula is used in sub-portfolio.
Presently preferred embodiments of the present invention is the foregoing is only, is not intended to limit the invention, it is all in essence of the invention
Any modification, equivalent and improvement made within god and principle etc., should be included within the scope of the present invention.