CN109725382A - A kind of ultralow three rank OAM optical fiber of decaying low crosstalk weak coupling - Google Patents
A kind of ultralow three rank OAM optical fiber of decaying low crosstalk weak coupling Download PDFInfo
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Abstract
The present invention relates to a kind of ultralow three rank OAM optical fiber of decaying low crosstalk weak coupling, it include sandwich layer and covering, it is characterized in that sandwich layer be three layers, the Δ 1 of first sandwich layer is -0.7%~-0.2%, R1 is 3.5 μm~7 μm, the Δ 2 of second sandwich layer is 0.0%~0.5%, R2 is 5.5 μm~9 μm, the Δ 3 of third sandwich layer is -0.6%~0.1%, R3 is 7.5 μm~11.5 μm, and 2 > Δ of Δ, 3 > Δ 1, 3 μm≤R3-R1≤6 μm, sandwich layer is coated with covering, covering is made of one layer of sagging covering, or it is made of two layers of the covering of covering and pure silicon dioxide glass overclad that sink, sagging covering is the covering for closely surrounding sandwich layer, its Δ 4 is -0.9%~-0.6%, R4 is 38 μm~62. 5 μm.The present invention supports the OAM mode of three orders in 1550nm communication band highest, there is biggish effective refractive index difference and lower crosstalk between the nondegenerate OAM mode of different rank, there is lesser effective refractive index difference and lower DGD between the degenerate mode of identical order.
Description
Technical field
The present invention relates to a kind of three rank OAM (orbital angular momentum) of ultralow decaying low crosstalk weak coupling for optical communication system
Optical fiber belongs to technical field of optical fiber communication.
Background technique
For single mode optical fiber since its transmission rate is fast, it is big to carry information capacity, the advantages that long transmission distance, is widely used
Among Networks of Fiber Communications.In traditional optical transport network, time division multiplexing, wavelength-division multiplex, palarization multiplexing and phase are just
The technologies such as intermodulation have all been sufficiently applied in optical communication system the transmission capacity for improving simple optical fiber.And in recent years,
Demand with business such as communication, video, big datas to capacity is growing day by day, network bandwidth Rapid Expansion, optical transport network
Capacity is just gradually close to the shannon limit of simple optical fiber: 100Tb/s.Space division multiplexing and mode division multiplexing technology are not filled also uniquely
The technology separately sent out and used, the technology can bring the promotion of the order of magnitude for simple optical fiber transmission capacity, can break tradition
Shannon limit, realize more high bandwidth transmission.Experiment show the mode division multiplexing technology based on less fundamental mode optical fibre can one with
On space-propagation mode under transmit signal, by multiple-input and multiple-output (MIMO) Digital Signal Processing by all modes
It demodulates and, to realize the transmission of more high bandwidth higher frequency spectrum efficiency, therefore have received widespread attention.However, with being
It unites the extension of capacity and the increase of transmission range, the complexity of multiple-input and multiple-output algorithm also constantly rises in mode division multiplexing system
Height, the complexity of MIMO technology and the number of channel square and DGD size it is directly proportional, for example one supported lacking for six moulds multiplexing
Mode fiber Transmission system needs the crosstalk come between compensation model using 12 × 12 MIMO signal processing system in receiving end, this
Effective refractive index difference between a little modes is bigger, DGD is bigger, then the complexity of MIMO is higher, and this severely limits mode division multiplexing skills
The commercial prospect of art.Mode division multiplexing system based on weak coupling less fundamental mode optical fibre is suggested in recent years and in short-distance transmission scene
It is verified, in weak coupling mode division multiplexing system, intermode crosstalk is greatly restricted, to reduce answering for multiple-input and multiple-output algorithm
Miscellaneous degree, multiple-input and multiple-output algorithm is used for crosstalk between the mode inside balanced mode group, the mould between modal sets in these schemes
The method that formula separation can be detected by the pattern demultiplexer of physical layer and directly is realized.But weak coupling less fundamental mode optical fibre
In with modal sets order raising, the approximate degenerate mode number inside modal sets is consequently increased, the crosstalk between modal sets
Also with modal sets order increase and increase, therefore be used to balanced mode between crosstalk multiple-input and multiple-output algorithm complexity
Also it increases, limits the further dilatation of system.
OAM mode is another mode base group suitable for mode division multiplexing system, can be solved the above problems.Due to OAM
Ring core optical fiber radially constrains, and the mode radial direction order for supporting it is unique, it means that the model number in higher order mode group
Be always four, thus will not due to modal sets order raising and increase the complexity of multiple-input and multiple-output algorithm.Currently, can
OAM optical fiber and its application scenarios are divided into three types:
First, close coupling type OAM fiber optic applications are in long distance transmission.Between the mode for the different rank that this optical fiber is supported
Effective refractive index difference is smaller, coupling is stronger, be suitble to each mode in space point using MIMO technology and DSP processing system
It separates out and.Since MIMO processing technique is needed using instrument and equipment costly, and supported in its complexity and optical fiber
Pattern count it is square proportional, demodulating system will become considerably complicated and high if the pattern count in optical fiber is more
Expensive, this severely limits the promotions of pattern count in optical fiber, limit the promotion of simple optical fiber capacity, also make it extensive commercial uncommon
It hopes remote.And the decaying of this OAM optical fiber at present is all bigger, the decaying of optical signal in a fiber is very fast, be unable to satisfy it is long away from
Requirement from repeaterless transmission, which also limits application of the optical fiber in ultra-long span transmission.Chinese patent
CN105242347B proposes a kind of parabolic type OAM optical fiber, has lesser effective refractive index between the OAM mode in optical fiber
Poor and biggish crosstalk, in fact, being deposited simultaneously although this parabolic type multimode fibre can support high-order OAM mode
Radial higher order mode the multiplexing of high-order OAM mode almost cannot achieve.And the loss of the optical fiber is larger, is 1dB/
km。
Second, weak coupling type OAM fiber optic applications are in middle and long distance transmission or data center's optical interconnection.This optical fiber is supported
Different rank mode between effective refractive index difference it is larger, the coupling between mode is weaker, does not need MIMO digital demodulation signal
System can be come out each modal cutoff in space using the method directly detected.Each high-order OAM mode includes four
A degenerate mode can not will couple too strong degenerate mode point due to separating the mode in space using the method directly detected
It comes, therefore transmission signal can only be used in one group of degenerate mode there are two the mode of different polarization states, other two mode rises
Less than the effect for improving channel quantity increase capacity, and the power loss of institute's use pattern can be bigger.In order to by every rank OAM mould
Degenerate mode in formula separates, and people devise a kind of airport OAM optical fiber, but the preparation method of the optical fiber is complicated, and performance is not
Stablize.
Third, during weak coupling mode division multiplexing optical fiber combination MIMO processing technique is used for or long distance transmission or data center's light
Interconnection.Effective refractive index difference between the mode for the different rank supported in this optical fiber is larger, coupling is weaker, using direct
The method of detection demodulates；Effective refractive index difference between the degenerate mode that the mode of each order is included is smaller, coupling is stronger,
It is demodulated using MIMO digital information processing system.The mode quantity in optical fiber can be greatly improved in this way, improve single light
Fine transmission capacity, and the complexity and expense of mimo system can be reduced.But with the increase of Optical Fiber Transmission distance, ring core light
Crosstalk couplings between fine modal sets constantly increase, this is restricted the transmission range of ring core OAM optical fiber, need further
Crosstalk couplings between reduction mode.Chinese patent CN108051888A proposes a kind of ring core optical fiber of index dip, can
Effectively to inhibit the coupling in transmission process, increase optical fiber on the basis of not increasing system multiple-input and multiple-output algorithm complexity
Transmission range.But the loss of the optical fiber and specific relative refractive index are not mentioned.Come from the refractive index profile of patent disclosure
It sees, in order to reach the relative index of refraction requirement of annular region, needs largely to mix germanium, so that the Rayleigh scattering in optical fiber is larger, decline
Subtract larger.Chinese patent CN104003614B, CN108680990A propose a kind of toroidal cores OAM optical fiber respectively, in optical fiber
There is biggish effective refractive index difference and lesser crosstalk, but the loss of optical fiber is larger, respectively reaches 2.0dB/ between OAM mode
km、1.8dB/km。
Due to the particularity of OAM mode, OAM optical fiber mentioned above is required to form one with higher phase in fibre core
The annular region of refractive index difference, could support OAM mode to transmit in a fiber, in order to reach this higher relative index of refraction
Difference needs to improve the doping concentration of the upper doped chemical such as germanium, phosphorus, increases the Rayleigh scattering in optical fiber, therefore the decaying of optical fiber
It is all bigger, usually in 1.0~2.0dB/km or so.In order to meet optical fiber telecommunications system to more large transmission power and longer transmission
The needs of distance development, the correlated performance of OAM optical fiber must have further promotion.Decaying and mode field diameter are two of optical fiber
Important performance indicator.The decaying of optical fiber is smaller, and transmission range of the optical signal in this medium is longer, the nothing of optical communication system
Repeater span is also longer, so as to substantially reduce relay station quantity, make while improving reliability of communication system construction and
Maintenance cost is greatly reduced；The mode field diameter of optical fiber is bigger, and effective area is bigger, then its nonlinear effect is weaker.Have greatly
Effect area can effectively inhibit the nonlinear effects such as Self-phase modulation, four-wave mixing, Cross-phase Modulation, guarantee high power light
The transmission quality of signal.The optical signal to noise ratio in optical fiber telecommunications system can be effectively improved by reducing decaying and increasing effective area,
Further increase the transmission range and transmission quality of system.For single mode optical fiber, the attenuation coefficient of optical fiber can use formula (1)
It indicates:
α=R/ λ4+αIR+αIM+αOH+αUV+B (1)
Wherein R is rayleigh scattering coefficient, αIR,αIM,αOH,αUVInfrared absorption, defect decaying are respectively represented, OH absorbs, and
UV absorption.In fiber optic materials, the scattering of the light due to caused by certain inhomogeneities much smaller than wavelength constitutes dissipating for optical fiber
Loss is penetrated, wherein Rayleigh scattering is one of three kinds of scattering mechanisms, is linear scattering (not generating the variation of frequency).Rayleigh scattering
Feature is inversely proportional with the biquadratic of wavelength, and the type of the loss and dopant material that are induced by it is related with concentration.For few mould
Optical fiber or OAM optical fiber, it is believed that the attenuation coefficient of each of optical fiber mode all follows above-mentioned formula (1).
Summary of the invention
Technical problem to be solved by the present invention lies in propose that a kind of ultralow decaying low crosstalk for optical communication system is weak
Three rank OAM optical fiber are coupled, it supports the OAM mode of three orders, the nondegenerate of different rank in 1550nm communication band highest
There is biggish effective refractive index difference and lower crosstalk between OAM mode, have between the degenerate mode of identical order lesser
Effective refractive index difference and lower DGD, the OAM optical fiber also have the characteristics that ultralow decaying and large effective area, make high over long distances
The optical transport of power is possibly realized.
Summary of the invention is introduced for convenience, is defined as follows term:
Prefabricated rods: meeting fiber design requirement by the radial refractive index distribution that sandwich layer and covering form can directly be drawn into
The glass bar or assembly of designed optical fiber；
Plug: the solid glass prefabricated component containing sandwich layer and part of clad；
Radius: the distance between this layer of outer boundary and central point；
Refractive index profile: the relationship between optical fiber or preform (including plug) glass refraction and its radius；
Relative fefractive index difference:
niAnd n0The refractive index of respectively each corresponding optical fiber each section and the refractive index of pure silicon dioxide glass；
The contribution amount of fluorine (F): relative index of refraction difference (Δ F) of fluorine doped (F) quartz glass relative to pure quartz glass, with
This come indicate fluorine doped (F) measure；
The contribution amount of germanium (Ge): relative index of refraction difference (Δ of germanium (Ge) quartz glass relative to pure quartz glass is mixed
Ge), measured with this to indicate to mix germanium (Ge)；
PCVD technique: with the quartz glass of plasma activated chemical vapour deposition method preparation required thickness；
MCVD technique: with the quartz glass of improved chemical vapor deposition method preparation required thickness；
OVD technique: with the quartz glass of Outside Vapor deposition and sintering process preparation required thickness；
VAD technique: with the quartz glass of axial vapor deposition and sintering process preparation required thickness；
APVD over cladding process: natural or synthetic silica flour is melted needed for mandrel surface preparation with high-frequency plasma flame
The SiO of thickness2Glass；
Bare fibre: refer to the glass fiber that coat is free of in optical fiber；
DGD: Differential Group Delay；
MIMO: MIMO technique.
The present invention be solve the problems, such as it is set forth above used by technical solution are as follows: include sandwich layer and covering, feature
It is that the sandwich layer is three layers, is followed successively by the first sandwich layer, the second sandwich layer and third sandwich layer from inside to outside, first sandwich layer
Relative fefractive index difference Δ 1 is -0.7%~-0.2%, and radius R1 is 3.5 μm~7 μm, the relative fefractive index difference of second sandwich layer
Δ 2 is 0.0%~0.5%, and radius R2 is 5.5 μm~9 μm, the relative fefractive index difference Δ 3 of the third sandwich layer is -0.6%~
0.1%, radius R3 are 7.5 μm~11.5 μm, and 2 > Δ of Δ, 31,3 μm≤R3-R1≤6 μm of > Δ, sandwich layer are coated with covering,
The covering is made of one layer of sagging covering, or is made of two layers of the covering of covering and pure silicon dioxide glass overclad that sink,
The sagging covering is the covering for closely surrounding sandwich layer, and relative fefractive index difference Δ 4 is -0.9%~-0.6%, and radius R4 is
38 μm~62.5 μm.
According to the above scheme, relative fefractive index difference Δ of the sagging cladding relative refractive difference Δ 4 less than the first sandwich layer
1, i.e. 4 < Δ 1 of Δ, and Δ 2- Δ 4 >=0.8%.
According to the above scheme, the covering is two layers of covering, and the radius R4 of the first covering is 38 μm~60 μm, the second covering
Radius R5 be 62.5um.
According to the above scheme, the sandwich layer is in step change type.
According to the above scheme, the optical fiber supports the OAM transmission mode of three stable orders at 1550nm wavelength.It is practical
Second order and three ranks the two high-orders OAM mode can be only used in communication system.
According to the above scheme, between high-order (second order and three ranks) OAM mode that the optical fiber is supported at 1550nm wavelength
Effective refractive index difference is greater than or equal to 1.8*10-3, 3.1*10 is greater than or equal under optimum condition-3。
According to the above scheme, the difference of effective refractive index of the optical fiber between all degenerate modes that identical order is included
Respectively less than or equal to 2.3*10-5。
According to the above scheme, attenuation coefficient of the OAM mode that the optical fiber is supported at 1550nm wavelength is respectively less than or waits
It is less than or equal to 0.22dB/km under 0.25dB/km, optimum condition.
According to the above scheme, the effective area of high-order OAM mode optical fiber at 1550nm wavelength is greater than or equal to 150 μ
m2。
According to the above scheme, quartz glass of each sandwich layer by fluorine doped (F) and germanium (Ge), or the stone mixed with (Ge)
English glass, or formed mixed with the quartz glass or pure quartz glass of fluorine (F).Also other dopants can be used, as phosphorus, boron,
Nitrogen, chlorine etc..
According to the above scheme, mixed with alkali metal element in the second sandwich layer and third sandwich layer.
The beneficial effects of the present invention are: 1. fibre cores have the cross-section structure of multi-level step change type, communicate in 1550nm
Wave band highest supports three rank OAM modes, the OAM mode for stablizing three orders of transmission in optical fiber to have ultralow decaying, thus
Long distance transmission may be implemented, construction associated base stations and the cost of other system equipments can also be reduced in primary transmission.It declines
Factor in terms of subtracting performance and depending on following two: firstly, the quartzy glass of the first covering or entire covering using deep fluorine doped (F)
Glass, relative fefractive index difference is biggish negative value, while so that biggish core packet refringence is guaranteed, sandwich layer relative
Rate absolute value of the difference is smaller, and doping concentration is lower, and the especially relative fefractive index difference of the second sandwich layer or third sandwich layer is substantially zeroed,
Doping concentration is close to zero, and the mould field of OAM mode is distributed mainly on the second sandwich layer and third sandwich layer, and the reduction of doping concentration is very
To close to zero, then loss caused by Rayleigh scattering reduces, so that the decaying of optical fiber is very significantly improved.Secondly,
Alkali metal element is mixed in the second sandwich layer of optical fiber and third sandwich layer, so that the viscosity of fiber core layer is improved, to increase
The uniformity of material reduces the decaying of optical fiber.2. optical fiber highest supports the transmission of stablizing of three rank OAM modes, and every rank OAM mould
Have biggish effective refractive index poor between formula, to have lower crosstalk to be conducive to directly demodulate.Due to high-order OAM mode
Between effective refractive index difference it is bigger, second order and three ranks the two high-orders OAM mode can be only used in practical communication system.
The relative fefractive index difference of the first sandwich layer is less than the relative fefractive index difference of second and third sandwich layer, and second sandwich layer in fibre profile
Relative fefractive index difference is significantly higher than the first covering, and the refractive index profile of optical fiber is enabled to support the OAM mould of annular mode distributions
Formula.The relative fefractive index difference of second sandwich layer is greater than third sandwich layer, and the relative fefractive index difference of the first sandwich layer is greater than the first covering, and second
Relative fefractive index difference between the difference of relative fefractive index difference and the first sandwich layer and the first covering between sandwich layer and third sandwich layer
Difference to generate that biggish effective refractive index is poor between high-order OAM mode, so that the crosstalk between reduction mode is conducive to directly solution
It adjusts.In addition, the effective refractive index difference between the degenerate mode that each high-order OAM mode of the optical fiber is included is smaller, DGD is smaller, can
To be separated with 4 × 4 MIMO processing system, therefore the number of mode multiplexing is increased to the maximum extent, improve single light
Fine transmission capacity, and reduce the complexity of MIMO processing system and algorithm.3. the OAM for three orders that the optical fiber is supported
Mode makes optical transport high-power over long distances become possibility in addition to also having biggish effective area with ultralow decaying.
Detailed description of the invention
Fig. 1 is the radial cross section of one embodiment of the present of invention.First sandwich layer of 00 corresponding optical fiber in figure, 10 pairs
Answer the second sandwich layer of optical fiber, the third sandwich layer of 20 corresponding optical fiber, the first covering namely surrounding layer of 30 corresponding optical fiber.
Fig. 2 is the refractive index profile figure of one embodiment of the present of invention corresponding to Fig. 1.
Fig. 3 is the three rank OAM moulds that the OAM optical fiber of one embodiment of the present of invention corresponding to Fig. 1 is supported at 1550nm
The normalization field pattern of formula.
Fig. 4 is the radial cross section of another embodiment of the invention.First sandwich layer of 00 corresponding optical fiber in figure, 10
Second sandwich layer of corresponding optical fiber, the third sandwich layer of 20 corresponding optical fiber, the first covering of 30 corresponding optical fiber, the outsourcing of 40 corresponding optical fiber
Layer.
Fig. 5 is the refractive index profile figure of another embodiment of the invention corresponding to Fig. 4.
Fig. 6 is the three rank OAM that the OAM optical fiber of another embodiment of the invention corresponding to Fig. 4 is supported at 1550nm
The normalization field pattern of mode.
Specific embodiment
Below with reference to embodiment, the present invention is described in further detail.
Embodiment one: bare fibre includes three layers of sandwich layer and one layer of covering, as shown in Figure 1.First sandwich layer 00 is by fluorine doped
(F) and the quartz glass of a small amount of germanium (Ge) or the quartz glass of fluorine doped (F) composition；Second sandwich layer 10 is by mixing germanium (Ge) and mixing on a small quantity
The quartz glass of fluorine (F) or the quartz glass or pure quartz glass composition for mixing germanium (Ge) and a small amount of fluorine doped (F) on a small quantity, the second sandwich layer
In also a small amount of incorporation alkali metal element；Third sandwich layer 20 mixes the quartz glass of germanium (Ge) by fluorine doped (F) and on a small quantity or mixes germanium on a small quantity
(Ge) it and the quartz glass of a small amount of fluorine doped (F) or is made of pure quartz glass, also a small amount of incorporation alkali metal element in third sandwich layer.
Sandwich layer is prepared by PCVD technique, and the relative fefractive index difference size of three sandwich layers meets 2 > Δ of Δ, 3 > Δ 1.It is centered around outside sandwich layer
There is one layer of covering.Covering 30 closely surrounds sandwich layer, is made of the quartz glass of the deep fluorine doped (F) of PCVD or OVD technique preparation,
Relative fefractive index difference Δ 4 is -0.9%~0.6%, and Δ 2- Δ 4 >=0.8% ensure that biggish core packet refringence in optical fiber
And total reflection condition, and 4 < Δ 1 of Δ.Fig. 2 gives the refractive index profile structure chart according to optical fiber prepared by the embodiment.
Fig. 3 gives the normalization field distribution for the three rank OAM modes supported at 1550nm according to optical fiber prepared by the embodiment
Figure.
The coat of the present embodiment optical fiber is using the double-deck coating processes, and drawing speed is 500-2000m/min, optical fiber
String diameter is 125 ± 0.7 μm.
According to the technical solution of above-mentioned OAM optical fiber, the parameter of optical fiber is designed in the range of its defined, and is led to
The plugs manufacturing process such as known PCVD technique, MCVD technique, OVD technique or VAD technique are crossed according to the design requirement system of optical fiber
Plug is made, the manufacture of entire prefabricated rods is completed by over cladding process such as casing technique, OVD technique or VAD techniques.
The refractive index profile of institute's drawing optical fiber is tested using NR-9200 equipment (EXFO), the refractive index profile of optical fiber
And special doping situation is as shown in table 1.
The Specifeca tion speeification of institute's drawing optical fiber is as shown in table 2.Wherein OAM2,1 represents second-order OAM mode, OAM3, and 1
Represent third rank OAM mode.
Statistics indicate that optical fiber manufactured by technical solution according to the invention, is supported stable at 1550nm wavelength
The OAM transmission mode of three orders, wherein the effective refractive index difference between high-order (second order and three ranks) OAM mode is greater than or waits
In 1.8*10-3, 3.1*10 is greater than or equal under optimum condition-3.Attenuation coefficient of all OAM modes at 1550nm wavelength is equal
Less than or equal to 0.25dB/km, it is less than or equal to 0.22dB/km under optimum condition.High-order OAM mode is at 1550nm wavelength
Effective area is greater than 150 μm2。
Table 1: the structure and material composition of one OAM optical fiber of embodiment
Table 2: the Specifeca tion speeification of one OAM optical fiber of embodiment
Embodiment two: bare fibre includes three layers of sandwich layer and two layers of covering, as shown in Figure 4.First sandwich layer 00 is by fluorine doped
(F) and on a small quantity the quartz glass of germanium (Ge) or the quartz glass composition of fluorine doped (F) are mixed；Second sandwich layer 10 is by mixing germanium (Ge) and a small amount of
The quartz glass of fluorine doped (F) or the quartz glass or pure quartz glass composition for mixing germanium (Ge) and a small amount of fluorine doped (F) on a small quantity, the second core
Also a small amount of incorporation alkali metal element in layer；Third sandwich layer 20 is mixed the quartz glass of germanium (Ge) by fluorine doped (F) and on a small quantity or is mixed on a small quantity
The quartz glass of germanium (Ge) and a small amount of fluorine doped (F) is made of pure quartz glass, also a small amount of incorporation alkali metal member in third sandwich layer
Element.Sandwich layer is prepared by PCVD technique, and the relative index of refraction size of three sandwich layers meets 2 > Δ of Δ, 3 > Δ 1.It is centered around sandwich layer
There is two layers of covering outside.Covering 30 is the first covering for closely surrounding sandwich layer, by the deep fluorine doped (F) of PCVD or OVD technique preparation
Quartz glass composition, relative fefractive index difference Δ 4 are -0.9%~0.6%, and Δ 2- Δ 4 >=0.8% ensure that larger in optical fiber
Core packet refringence and total reflection condition, and 4 < Δ 1 of Δ.Second covering 40 is the surrounding layer of the first covering of tight enclosure, by
The pure quartz glass composition of PCVD or OVD technique preparation, relative fefractive index difference Δ 5 are 0%, and radius R5 is 62.5 μm.Fig. 5 gives
The refractive index profile structure chart according to optical fiber prepared by the embodiment is gone out.Fig. 6 gives according to prepared by the embodiment
The normalization field pattern of three rank OAM modes supported at 1550nm of optical fiber.
The stick technique processed of the present embodiment optical fiber, drawing process and coating processes are identical with above-mentioned first embodiment.Optical fiber
String diameter be 125 ± 0.7 μm.
The refractive index profile of institute's drawing optical fiber is tested using NR-9200 equipment (EXFO), the refractive index profile of optical fiber
And special doping situation is as shown in table 3.The fade performance parameter of institute's drawing optical fiber is as shown in table 4.
Embodiment optical fiber and first group of embodiment manufactured by technical solution according to the invention are compared, other section ginsengs
Number is constant, only increases one layer of pure glass overclad, and the first cladding radius R4 is 38 μm~60 μm, pure glass overclad
Addition will not influence optical fiber fundamental performance parameter, for example, optical fiber supported pattern count, the effective refractive index difference between mode,
And the effective area of mode.Therefore it is not repeated to list performance parameter result.The decaying of mode may be subjected to the influence of R4,
When R4 is sufficiently large, the fade performance of mode will not influence, therefore, the minimum value of R4 is limited in 38 μm by us.All OAM moulds
Attenuation coefficient of the formula at 1550nm wavelength is respectively less than or is equal to 0.25dB/km, is less than or equal to 0.22dB/ under optimum condition
km。
Table 3: the structure and material composition of two OAM optical fiber of embodiment
Table 4: the fade performance of two OAM optical fiber of embodiment
Claims (9)
1. a kind of ultralow three rank OAM optical fiber of decaying low crosstalk weak coupling, includes sandwich layer and covering, it is characterised in that the core
Layer is three layers, is followed successively by the first sandwich layer, the second sandwich layer and third sandwich layer, the relative fefractive index difference of first sandwich layer from inside to outside
Δ 1 is -0.7%~-0.2%, and radius R1 is 3.5 μm~7 μm, the relative fefractive index difference Δ 2 of second sandwich layer is 0.0%~
0.5%, radius R2 are 5.5 μm~9 μm, and the relative fefractive index difference Δ 3 of the third sandwich layer is -0.6%~0.1%, radius R3
Be 7.5 μm~11.5 μm, and 2 > Δ of Δ, 31,3 μm≤R3-R1≤6 μm of > Δ, sandwich layer is coated with covering, the covering by
One layer of sagging covering is constituted, or is made of two layers of the covering of covering and pure silicon dioxide glass overclad that sink, the sagging packet
Layer is the covering for closely surrounding sandwich layer, and relative fefractive index difference Δ 4 is -0.9%~-0.6%, and radius R4 is 38 μm~62.5 μ
m。
2. three rank OAM optical fiber of ultralow decaying low crosstalk weak coupling according to claim 1, it is characterised in that the sagging packet
Relative fefractive index difference Δ 1 of the layer relative fefractive index difference Δ 4 less than the first sandwich layer, i.e. 4 < Δ 1 of Δ, and Δ 2- Δ 4 >=0.8%.
3. three rank OAM optical fiber of ultralow decaying low crosstalk weak coupling as described in claim 1 or 2, it is characterised in that the packet
Layer is two layers of covering, and the radius R4 of the first covering is 38 μm~60 μm, and the radius R5 of the second covering is 62.5um.
4. three rank OAM optical fiber of ultralow decaying low crosstalk weak coupling as described in claim 1 or 2, it is characterised in that the core
Layer is in step change type.
5. three rank OAM optical fiber of ultralow decaying low crosstalk weak coupling as described in claim 1 or 2, it is characterised in that the optical fiber
The OAM transmission mode of three stable orders is supported at 1550nm wavelength.
6. three rank OAM optical fiber of ultralow decaying low crosstalk weak coupling as described in claim 5, it is characterised in that the optical fiber exists
The effective refractive index difference between high-order OAM mode supported at 1550nm wavelength is greater than or equal to 1.8*10-3。
7. three rank OAM optical fiber of ultralow decaying low crosstalk weak coupling as described in claim 5, it is characterised in that the optical fiber is in phase
The difference for the effective refractive index between all degenerate modes for being included with order is respectively less than or is equal to 2.3*10-5。
8. three rank OAM optical fiber of ultralow decaying low crosstalk weak coupling as described in claim 1 or 2, it is characterised in that the optical fiber
Attenuation coefficient of the OAM mode supported at 1550nm wavelength is respectively less than or is equal to 0.25dB/km.
9. three rank OAM optical fiber of ultralow decaying low crosstalk weak coupling according to claim 6, it is characterised in that the high-order OAM
The effective area of mode optical fiber at 1550nm wavelength is greater than or equal to 150 μm2。
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| CN201910170385.9A CN109725382B (en) | 2019-03-07 | 2019-03-07 | Ultralow-attenuation low-crosstalk weak-coupling third-order OAM optical fiber |
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| CN201910170385.9A CN109725382B (en) | 2019-03-07 | 2019-03-07 | Ultralow-attenuation low-crosstalk weak-coupling third-order OAM optical fiber |
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| CN201910170385.9A Active CN109725382B (en) | 2019-03-07 | 2019-03-07 | Ultralow-attenuation low-crosstalk weak-coupling third-order OAM optical fiber |
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