WO2013042568A1 - 光伝送路 - Google Patents
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- WO2013042568A1 WO2013042568A1 PCT/JP2012/073040 JP2012073040W WO2013042568A1 WO 2013042568 A1 WO2013042568 A1 WO 2013042568A1 JP 2012073040 W JP2012073040 W JP 2012073040W WO 2013042568 A1 WO2013042568 A1 WO 2013042568A1
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- 230000003287 optical effect Effects 0.000 title claims abstract description 76
- 230000005540 biological transmission Effects 0.000 title claims abstract description 42
- 239000013307 optical fiber Substances 0.000 claims abstract description 298
- 238000005253 cladding Methods 0.000 claims description 42
- 230000008878 coupling Effects 0.000 claims description 22
- 238000010168 coupling process Methods 0.000 claims description 22
- 238000005859 coupling reaction Methods 0.000 claims description 22
- 239000000835 fiber Substances 0.000 abstract description 15
- 230000000694 effects Effects 0.000 abstract description 2
- 230000008033 biological extinction Effects 0.000 abstract 1
- 238000005452 bending Methods 0.000 description 21
- 238000010586 diagram Methods 0.000 description 12
- 238000005259 measurement Methods 0.000 description 10
- 238000004364 calculation method Methods 0.000 description 6
- 230000000994 depressogenic effect Effects 0.000 description 6
- 230000007423 decrease Effects 0.000 description 3
- 230000005684 electric field Effects 0.000 description 3
- 230000001902 propagating effect Effects 0.000 description 3
- 230000006798 recombination Effects 0.000 description 3
- 238000005215 recombination Methods 0.000 description 3
- 230000005284 excitation Effects 0.000 description 2
- 238000002474 experimental method Methods 0.000 description 2
- 238000000034 method Methods 0.000 description 2
- 230000010287 polarization Effects 0.000 description 2
- 230000001419 dependent effect Effects 0.000 description 1
- 230000004927 fusion Effects 0.000 description 1
- 238000007526 fusion splicing Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 230000000644 propagated effect Effects 0.000 description 1
- 238000012360 testing method Methods 0.000 description 1
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
- G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
- G02B6/03622—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 2 layers only
- G02B6/03627—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 2 layers only arranged - +
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/028—Optical fibres with cladding with or without a coating with core or cladding having graded refractive index
- G02B6/0283—Graded index region external to the central core segment, e.g. sloping layer or triangular or trapezoidal layer
- G02B6/0285—Graded index layer adjacent to the central core segment and ending at the outer cladding index
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
- G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
- G02B6/03638—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only
- G02B6/0365—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 3 layers only arranged - - +
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/255—Splicing of light guides, e.g. by fusion or bonding
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/14—Mode converters
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
Definitions
- the present invention relates to an optical transmission line including a low bending loss optical fiber (BIF).
- BIF low bending loss optical fiber
- the optical fiber is required to have a small bending loss, particularly in the FTTx system.
- the BIF is used in a place where bending is easily given, such as a central office wiring.
- BIF is an ITU-T Recommendation G. 657, and grades A1, A2, B2, and B3 are divided according to the magnitude of the bending loss, and B3 has the smallest bending loss.
- an optical fiber having a trench type refractive index structure having an annular groove having a low refractive index in the cladding, and a depressed type refractive index structure in which the refractive index of the cladding is lower than the refractive index of the jacket Optical fibers are known.
- a BIF having a trench type or depressed type refractive index structure can realize low bending loss by strongly confining light in the core by a groove or a low refractive index cladding provided around the core.
- BIF not only has a small bending loss in the fundamental mode, but also has a small bending loss in the higher mode.
- the BIF is assumed to be used in a short length of several meters in the house or under bending.
- Non-Patent Document 2 Statistical Analysis of MPI in Bend-insensitive Fibers OFC 2009 OTuL1 (Non-Patent Document 2) -30dB for MPI for error-free transmission in the case of 10Gbps optical transmission It is stated that it is necessary to make it less than.
- the present invention relates to ITU-T Recommendation G. It is an object of the present invention to provide an optical transmission line that includes a low bending loss optical fiber (BIF) defined by 657 and suppresses the influence of MPI.
- BIF low bending loss optical fiber
- a core including a central axis, a first optical cladding layer surrounding the core, a second optical cladding layer surrounding the first optical cladding layer, and surrounding the second optical cladding layer A jacket layer, wherein the relative refractive index difference ⁇ 1 of the core is 0.25 to 0.37%, the relative refractive index difference ⁇ 2 of the first optical cladding layer is 0% or more and less than ⁇ 1, and the second optical cladding a is the relative refractive index difference ⁇ 3 of the layers are less -0.2%, a first optical fiber attenuation coefficient is alpha 11 at the wavelength 1310nm of LP11 mode, which is connected to one end of (2) the first optical fiber An optical transmission line in which a second optical fiber and (3) a third optical fiber connected to the other end of the first optical fiber are laid, and a connection loss A between the first optical fiber and the second optical fiber.
- the “relative refractive index difference” means a difference (n object ⁇ n jacket ) / n jacket between the refractive index of each part and the refractive index of the jacket layer with respect to the refractive index of the jacket layer.
- each of the second optical fiber and the third optical fiber is a general-purpose single mode optical fiber, and in the connection between the first optical fiber and the general-purpose single mode optical fiber, the LP11 mode and the general-purpose single mode light of the first optical fiber.
- the coupling efficiency with the LP01 mode of the fiber may be 0.5 or less.
- each of the second optical fiber and the third optical fiber may be a general-purpose single mode optical fiber, and the difference in mode field diameter between the first optical fiber and the general-purpose single mode optical fiber at a wavelength of 1310 nm may be 1 ⁇ m or less.
- the general-purpose single mode optical fiber is ITU-T recommendation G.264. This is an optical fiber conforming to 652.
- a core including a central axis, a first optical cladding layer surrounding the core, a second optical cladding layer surrounding the first optical cladding layer, and the second optical cladding layer are provided.
- the core has a relative refractive index difference ⁇ 1 of 0.25 to 0.37%, the relative refractive index difference ⁇ 2 of the first optical cladding layer is 0% or more and less than ⁇ 1, and the second optical relative refractive index difference ⁇ 3 of the clad layer is not more than -0.2%, and the first optical fiber attenuation coefficient is alpha 11 at the wavelength 1310nm of LP11 mode, is connected to one end of (2) the first optical fiber
- the second optical fiber is an optical transmission line in which the connection loss between the first optical fiber and the second optical fiber is A, and the length L [m] of the first optical fiber is expressed by the following equation: : An optical transmission line satisfying the above is provided.
- the second optical fiber is a general-purpose single-mode optical fiber, and the connection between the first optical fiber and the general-purpose single-mode optical fiber is between the LP11 mode of the first optical fiber and the LP01 mode of the general-purpose single-mode optical fiber.
- the coupling efficiency may be 0.5 or less.
- the second optical fiber may be a general-purpose single mode optical fiber, and the difference in mode field diameter between the first optical fiber and the general-purpose single mode optical fiber at a wavelength of 1310 nm may be 1 ⁇ m or less.
- a core including a central axis, an optical cladding layer surrounding the core, and a jacket layer surrounding the optical cladding layer the core has a relative refractive index difference ⁇ 1 of 0. 25 is ⁇ 0.37%, a relative refractive index difference ⁇ 2 of the optical cladding layer is 0% or more and less than -0.3%, and the first optical fiber attenuation coefficient is alpha 11 at the wavelength 1310nm of LP11 mode
- an optical transmission line in which a second optical fiber connected to one end of the first optical fiber and (3) a third optical fiber connected to the other end of the first optical fiber are laid The connection loss between the first optical fiber and the second optical fiber is A, the connection loss B between the first optical fiber and the third optical fiber, and the length L [m] of the first optical fiber is represented by the formula (3). :
- An optical transmission line satisfying the above is provided.
- each of the second optical fiber and the third optical fiber is a general-purpose single mode optical fiber, and in the connection between the first optical fiber and the general-purpose single mode optical fiber, the LP11 mode and the general-purpose single mode light of the first optical fiber.
- the coupling efficiency with the LP01 mode of the fiber may be 0.5 or less.
- each of the second optical fiber and the third optical fiber may be a general-purpose single mode optical fiber, and the difference in mode field diameter between the first optical fiber and the general-purpose single mode optical fiber at a wavelength of 1310 nm may be 1 ⁇ m or less.
- a core including a central axis, an optical cladding layer surrounding the core, and a jacket layer surrounding the optical cladding layer, the core has a relative refractive index difference ⁇ 1 of 0. is from 25 to 0.37%, the relative refractive index difference ⁇ 2 of the optical cladding layer is less than 0% or more -0.3%, a first optical fiber is an attenuation coefficient alpha 11 at the wavelength 1310nm of LP11 mode, (2) An optical transmission line in which a second optical fiber connected to one end of the first optical fiber is laid, and a connection loss A between the first optical fiber and the second optical fiber, and the first optical fiber The length L [m] is the formula (4): An optical transmission line satisfying the above is provided.
- the second optical fiber is a general-purpose single-mode optical fiber, and the connection between the first optical fiber and the general-purpose single-mode optical fiber is between the LP11 mode of the first optical fiber and the LP01 mode of the general-purpose single-mode optical fiber.
- the coupling efficiency may be 0.5 or less.
- the second optical fiber may be a general-purpose single mode optical fiber, and the difference in mode field diameter between the first optical fiber and the general-purpose single mode optical fiber at a wavelength of 1310 nm may be 1 ⁇ m or less.
- ITU-T Recommendation G It is possible to provide an optical transmission line including a low bending loss optical fiber (BIF) defined by 657 and in which the influence of MPI is suppressed.
- BIF low bending loss optical fiber
- FIG. 1 is a conceptual diagram of a measurement system of Example 1.
- Example 3 is a graph showing the relationship between MPI experimental values and MPI calculated values in Example 1.
- FIG. 6 is a conceptual diagram of a measurement system 4 in Example 2.
- FIG. 6 is a conceptual diagram of a measurement system 4 in Example 2.
- Example 10 is a graph showing the relationship between the measured MPI value and the number of staples in Example 3.
- FIG. 1 is a conceptual diagram showing a refractive index distribution of a BIF having a trench type refractive index structure.
- the trench type BIF includes a core (radius r1) including a central axis, a first optical cladding layer (radius r2) surrounding the core, a second optical cladding layer (radius r3) surrounding the first optical cladding layer, 2 having a jacket layer surrounding the optical cladding layer.
- the relative refractive index difference ⁇ 1 of the core is 0.25 to 0.37%
- the relative refractive index difference ⁇ 2 of the first optical cladding layer is 0% or more
- the relative refractive index of the second optical cladding layer is The rate difference ⁇ 3 is ⁇ 0.2% or less and satisfies the relationship ⁇ 1> ⁇ 2> ⁇ 3.
- Such a BIF is an ITU-T recommendation G.264. 657. Satisfy B3.
- FIG. 2 is a conceptual diagram showing a refractive index distribution of a BIF having a depressed type refractive index structure.
- the depressed BIF has a core (radius r1) including a central axis, an optical cladding layer (radius r2) surrounding the core, and a jacket layer surrounding the optical cladding layer.
- the relative refractive index difference ⁇ 1 of the core is 0.25 to 0.37%
- the relative refractive index difference ⁇ 2 of the optical cladding layer is ⁇ 0.3% or more and less than 0%.
- Such optical fibers are described in ITU-T Recommendation G. 657. Satisfies A2.
- FIG. 3 is a conceptual diagram illustrating the configuration of the optical transmission line 1 of the first embodiment and the MPI there.
- the optical transmission line 1 includes a first optical fiber 11, a second optical fiber 12 connected to the incident end of the first optical fiber 11, and a third optical fiber 13 connected to the output end of the first optical fiber 11. Is provided.
- the first optical fiber 11 is a BIF
- each of the second optical fiber 12 and the third optical fiber 13 is a general-purpose single mode optical fiber.
- the general-purpose single mode optical fiber may have a substantially step type refractive index structure.
- a part of the fundamental mode (LP01 mode) propagating through the second optical fiber 12 is coupled to the higher-order mode (LP11 mode) at the connection portion between the second optical fiber 12 and the first optical fiber 11. Both the fundamental mode (LP01 mode) and the higher order mode (LP11 mode) are incident on the first optical fiber 11. Most of the fundamental mode (LP01 mode) propagating through the first optical fiber 11 is coupled to the fundamental mode (LP01 mode) at the connection portion between the first optical fiber 11 and the third optical fiber 13. In addition, the higher order mode (LP11 mode) that has propagated through the first optical fiber 11 is partly coupled to the fundamental mode (LP01 mode) at the connection portion between the first optical fiber 11 and the third optical fiber 13.
- a fundamental mode derived from the fundamental mode in the first optical fiber 11 (hereinafter referred to as “basic component”) and a fundamental mode derived from the higher-order mode in the first optical fiber 11 (hereinafter referred to as “basic component”). "Higher order component”).
- MPI fundamental mode derived from the fundamental mode in the first optical fiber 11
- base component fundamental mode derived from the higher-order mode in the first optical fiber 11
- MPI Higher order component
- the electric field of the base component is represented as E 0 exp (j ⁇ 0 ), and the electric field of the higher order component is represented as ⁇ E 0 exp (j ⁇ 1 ).
- the electric field of the fundamental mode (LP01 mode) in the third optical fiber 13 is represented by the equation (5a)
- the intensity of the fundamental mode (LP01 mode) in the third optical fiber 13 is represented by the equation (5b).
- MPI is expressed by equation (6).
- the intensity represented by the equation (5b) is observed as the intensity of the guided light of the third optical fiber 13.
- the received light intensity becomes the maximum value
- the phase difference between the base component and the higher order component is ⁇
- the ratio ptp (Peak to Peak) between the maximum value and the minimum value of the received light intensity is expressed by equation (7).
- Expression (7) is used, Expression (6) is expressed by Expression (8).
- the coupling efficiency from the fundamental mode of the second optical fiber 12 to the fundamental mode of the first optical fiber 11 at the junction between the second optical fiber 12 and the first optical fiber 11 is expressed as ⁇ 01 ⁇ .
- a 01, 1 represents the coupling efficiency to the higher-order mode of the first optical fiber 11 and eta 01-11,1 from the fundamental mode of the second optical fiber 12.
- the coupling efficiency from the fundamental mode of the first optical fiber 11 to the fundamental mode of the third optical fiber 13 at the junction between the first optical fiber 11 and the third optical fiber 13 is represented by ⁇ 01-01
- the coupling efficiency from the higher order mode of the optical fiber 11 to the fundamental mode of the third optical fiber 13 is represented by ⁇ 11-01,1 .
- the length of the first optical fiber 11 is L.
- the attenuation coefficient of the higher-order mode in the first optical fiber 11 is expressed as ⁇ 11.
- the transmission loss [dB] of the higher-order mode in the first optical fiber 11 is represented by 10 ⁇ log 10 (exp ( ⁇ 11 L)). It is assumed that the fundamental mode attenuation in the first optical fiber 11 is zero.
- the intensity P 01 of the base component in the third optical fiber 13 is expressed by equation (9).
- Intensity P 11 of high-order components of the third optical fiber 13 is expressed by equation (10).
- MPI is expressed by equation (11). When the equation (11) is used, MPI can be predicted from ⁇ and ⁇ of the measurement system.
- the MPI is the coupling efficiency ⁇ 01-01,1 , ⁇ 01-11 , 1 , ⁇ 01-01 , 2 ⁇ 11-01 , 2 , higher order in the first optical fiber 11 It is determined by the mode attenuation coefficient ⁇ 11 and the length L of the first optical fiber 11.
- the coupling efficiency ⁇ 01-11,1 and the coupling efficiency ⁇ 11-01,1 are made as small as possible, the attenuation coefficient ⁇ 11 is made as large as possible, and L is made as long as possible. It is desirable.
- the coupling efficiency is determined by the difference in mode field diameter between two optical fibers connected to each other and the amount of axial deviation. In order to reduce MPI, it is desirable to reduce the difference in mode field diameter and the amount of axial deviation. Note that the coupling efficiency ⁇ 01-01,1 , ⁇ 01-01,2 in dB represents a connection loss. In other words, the smaller the connection loss, the better the MPI.
- the coupling efficiency ⁇ 01-11,1 is preferably 0.5 or less, and the coupling efficiency ⁇ 11-01,1 is preferably 0.5 or less.
- the difference of the mode field diameter in wavelength 1310nm of each of the 1st optical fiber 11 and the 2nd optical fiber 12 is 1 micrometer or less.
- the difference in mode field diameter between the first optical fiber 11 and the third optical fiber 13 at a wavelength of 1310 nm is preferably 1 ⁇ m or less.
- the higher-order mode attenuation coefficient ⁇ 11 in the first optical fiber 11 is determined by the laying state of the first optical fiber 11 (a given bending diameter) and the refractive index profile of the first optical fiber 11.
- eta, at any value alpha 11 is, by increasing the length L of the first optical fiber 11, it is possible to reduce the MPI.
- FIG. 4 is a graph showing the relationship between the length L of the first optical fiber 11 and the MPI calculation value at a wavelength of 1310 nm.
- the connection loss between the first optical fiber 11 and the second optical fiber 12 is 1.0 dB
- the connection loss between the first optical fiber 11 and the third optical fiber 13 is 1.0 dB.
- ⁇ 01-01,1 0.78
- ⁇ 01-01,1 0.78
- ⁇ 01-11,1 0.21
- ⁇ 11-01.2 0.21
- the efficiency of coupling to the mode is 0.01.
- Three types of first optical fibers 11 with different high-order mode attenuation coefficients ⁇ 11 were assumed. Each of the attenuation coefficient alpha 11 was 0.39,1.65,5.48.
- the other two types of first optical fibers (BIF) 11 are G.I. 657. Satisfies A2.
- the MPI decreases as the length L of the first optical fiber 11 increases.
- FIG. 5 is a graph showing the relationship between the connection loss at the wavelength of 1310 nm and the MPI calculation value in the first embodiment.
- the length L of the first optical fiber 11 is 1 m.
- the attenuation coefficient alpha 11 of higher-order mode of the first optical fiber 11 was set to 0.39.
- the connection loss between the first optical fiber 11 and the second optical fiber 12 is assumed to be equal to the connection loss between the first optical fiber 11 and the third optical fiber 13.
- the MPI increases as the connection loss increases. If the connection loss at both ends of the first optical fiber 11 is 0.3 dB or less, the MPI is less than ⁇ 30 dB.
- connection loss is determined by the connection method (fusion, V-connection, mechanical splice)
- the degree of freedom of the value is low. Therefore, as a technique for suppressing the MPI of the system, it is desirable to optimize the fiber length L after prescribing the connection state and limiting the range in which the connection loss can be taken.
- the minimum length with which the MPI is less than ⁇ 40 dB (the actual target MPI ⁇ 30 dB plus a margin of ⁇ 10 dB error (described later)).
- the equation for calculating L is expressed as equation (12).
- A is a connection loss [dB] between the second optical fiber 12 and the first optical fiber 11
- B is a connection loss [dB] between the first optical fiber 11 and the third optical fiber 13. .
- connection losses A and B are assumed to be less than 0.3 dB. In that case, 0.3 may be used as the values of the connection losses A and B.
- Attenuation coefficient alpha 11 of higher-order mode in the first optical fiber 11 since it is determined by the refractive index distribution varies from the fiber.
- the attenuation coefficient ⁇ 11 has wavelength dependence, and the attenuation coefficient ⁇ 11 increases as the wavelength increases in the wavelength range of 1310 to 1650 nm. Therefore, the MPI is often the largest at a wavelength of 1310 nm.
- ⁇ 11 in the 1310nm is, ITU-T Recommendation G. 657.
- the range of 0.2 to 0.5 is common for B3 compliant BIFs.
- FIG. 6 is a conceptual diagram illustrating the optical transmission line 2 and the MPI in the second embodiment.
- the optical transmission line 2 includes a first optical fiber 11, a second optical fiber 12 connected to the incident end of the first optical fiber 11, and a light receiver 14 that receives the guided light of the second optical fiber 12.
- the first optical fiber 11 is a BIF
- the second optical fiber 12 is a general-purpose single mode optical fiber.
- MPI is expressed by the equation (13).
- the coupling efficiency from the fundamental mode of the second optical fiber 12 to the fundamental mode of the first optical fiber 11 at the junction between the second optical fiber 12 and the first optical fiber 11 is represented by ⁇ 01-01
- the coupling efficiency from the fundamental mode of the two optical fibers 12 to the higher order mode of the first optical fiber 11 was represented as ⁇ 01-11 .
- the minimum length for which the MPI is less than ⁇ 40 dB (the actual target MPI ⁇ 30 dB plus a margin of ⁇ 10 dB error (described later)).
- the equation for calculating L is expressed as equation (14).
- A is a connection loss [dB] between the second optical fiber 12 and the first optical fiber 11.
- the actual MPI can be set to ⁇ 30 dB by setting the length L of the first optical fiber 11 that satisfies the expression (14).
- G.C. corresponding to the optical fiber shown in FIG. 657.
- the MPI is generated by recombination with the fundamental mode at the bent portion or the connecting portion. Therefore, it is desirable to extend the formulas (12) and (14) to a shape including the influence of bending.
- higher order mode excitation due to bending and recombination to the fundamental mode are about an order of magnitude smaller than the effect of connection loss.
- MPI can be -30 dB.
- FIG. 7 is a conceptual diagram illustrating a schematic configuration of the measurement system 3 according to the first embodiment.
- the measurement system 3 measures the MPI by experiment for the optical transmission line 1 of the first embodiment.
- the first optical fiber 11 is a BIF, and three types of fibers 1 to 3 are used as the first optical fiber 11.
- the length L of the first optical fiber 11 was 1 m.
- Each of the second optical fiber 12 and the third optical fiber 13 was a general-purpose single mode optical fiber.
- the first optical fiber 11 and the second optical fiber 12 were fused and connected, and the first optical fiber 11 and the third optical fiber 13 were fused.
- a light source 15 is provided at the entrance end of the second optical fiber 12, and a light receiver 14 is provided at the exit end of the third optical fiber 13.
- a polarization scrambler 16 is provided in the middle of the second optical fiber 12.
- MPI at a wavelength of 1310 nm was measured by the measurement method described in Ming-Jun Li, et al (Non-patent Document 2). In addition, MPI at a wavelength of 1310 nm was calculated from the equation (11).
- FIG. 8 is a graph showing the relationship between the MPI experimental value and the MPI calculated value in Example 1.
- FIG. 9 is a conceptual diagram showing a schematic configuration of the measurement system 4 of the second embodiment.
- the measurement system 4 also measures the MPI by experiment for the optical transmission line 1 of the first embodiment.
- the first optical fiber 11 was BIF. Cylindrical objects having a radius of curvature of 5 mm were arranged at each of four corners of a square having a side length of 1 m, and the first optical fiber was wound only 20 times around them.
- Each of the second optical fiber 12 and the third optical fiber 13 was a general-purpose single mode optical fiber.
- the first optical fiber 11 and the second optical fiber 12 were connected by a V-groove, and the first optical fiber 11 and the third optical fiber 13 were connected by a V-groove.
- a light source 15 is provided at the entrance end of the second optical fiber 12, and a light receiver 14 is provided at the exit end of the third optical fiber 13.
- a polarization scrambler 16 is provided in the middle of the second optical fiber 12.
- the cut-off wavelength of the first optical fiber 11 was about 1250 nm.
- the measurement wavelength was 1310 nm.
- the connection loss was less than 0.3 dB.
- the bending loss at a curvature radius of 5 mm was less than 0.1 dB / turn.
- Example 3 a stapling test was performed on the first optical fiber (BIF) 11.
- BIF first optical fiber
- a BIF-encapsulated optical fiber cable with a diameter of 3 mm was stapled at intervals of about 5 cm, and the change in MPI was measured.
- FIG. 10 is a graph showing the relationship between the MPI measurement value and the number of staples in Example 3. As can be seen from FIG. 10, there is no significant change in the measured MPI value even when staples are driven at intervals of 5 cm. It can be seen from the given bend that the connection loss at the optical fiber connection is dominant over MPI.
- BIF low bending loss optical fibers
- a transmission error occurs by setting the length of the first optical fiber 11 to be equal to or longer than the length L of the MPI of less than ⁇ 30 dB in advance. Can be avoided.
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Abstract
Description
Claims (12)
- 中心軸を含むコアと、該コアを取り囲む第1光学クラッド層と、該第1光学クラッド層を取り囲む第2光学クラッド層と、該第2光学クラッド層を取り囲むジャケット層とを有し、前記コアの相対屈折率差Δ1が0.25~0.37%であり、前記第1光学クラッド層の相対屈折率差Δ2が0%以上Δ1未満であり、前記第2光学クラッド層の相対屈折率差Δ3が-0.2%以下であって、LP11モードの波長1310nmにおける減衰係数がα11である第1光ファイバと、
前記第1光ファイバの一端に接続された第2光ファイバと、
前記第1光ファイバの他端に接続された第3光ファイバと
が敷設された光伝送路であって、
前記第1光ファイバと前記第2光ファイバとの接続ロスAと、前記第1光ファイバと前記第3光ファイバとの接続ロスBと、前記第1光ファイバの長さL[m]とが(1)式:
- 請求項1に記載の光伝送路において、
前記第2光ファイバおよび前記第3光ファイバそれぞれが、汎用シングルモード光ファイバであり、
前記第1光ファイバと前記汎用シングルモード光ファイバとの接続において、前記第1光ファイバのLP11モードと前記汎用シングルモード光ファイバのLP01モードとの結合効率が0.5以下である。 - 請求項1に記載の光伝送路において、
前記第2光ファイバおよび前記第3光ファイバそれぞれが、汎用シングルモード光ファイバであり、
前記第1光ファイバおよび前記汎用シングルモード光ファイバそれぞれの波長1310nmにおけるモードフィールド径の差が1μm以下である。 - 中心軸を含むコアと、該コアを取り囲む第1光学クラッド層と、該第1光学クラッド層を取り囲む第2光学クラッド層と、該第2光学クラッド層を取り囲むジャケット層とを有し、前記コアの相対屈折率差Δ1が0.25~0.37%であり、前記第1光学クラッド層の相対屈折率差Δ2が0%以上Δ1未満であり、前記第2光学クラッド層の相対屈折率差Δ3が-0.2%以下であって、LP11モードの波長1310nmにおける減衰係数がα11である第1光ファイバと、
前記第1光ファイバの一端に接続された第2光ファイバと
が敷設された光伝送路であって、
前記第1光ファイバと前記第2光ファイバとの接続ロスをAと、前記第1光ファイバの長さL[m]とが下記の式:
- 請求項4に記載の光伝送路において、
前記第2光ファイバが、汎用シングルモード光ファイバであり、
前記第1光ファイバと前記汎用シングルモード光ファイバとの接続において、前記第1光ファイバのLP11モードと前記汎用シングルモード光ファイバのLP01モードとの結合効率が0.5以下である。 - 請求項4に記載の光伝送路において、
前記第2光ファイバが、汎用シングルモード光ファイバであり、
前記第1光ファイバおよび前記汎用シングルモード光ファイバそれぞれの波長1310nmにおけるモードフィールド径の差が1μm以下である。 - 中心軸を含むコアと、該コアを取り囲む光学クラッド層と、該光学クラッド層を取り囲むジャケット層とを有し、前記コアの相対屈折率差Δ1が0.25~0.37%であり、前記光学クラッド層の相対屈折率差Δ2が-0.3%以上0%未満であって、LP11モードの波長1310nmにおける減衰係数がα11である第1光ファイバと、
前記第1光ファイバの一端に接続された第2光ファイバと、
前記第1光ファイバの他端に接続された第3光ファイバと
が敷設された光伝送路であって、
前記第1光ファイバと前記第2光ファイバとの接続ロスをAと、前記第1光ファイバと前記第3光ファイバとの接続ロスBと、前記第1光ファイバの長さL[m]とが(3)式:
- 請求項7に記載の光伝送路において、
前記第2光ファイバおよび前記第3光ファイバそれぞれが、汎用シングルモード光ファイバであり、
前記第1光ファイバと前記汎用シングルモード光ファイバとの接続において、前記第1光ファイバのLP11モードと前記汎用シングルモード光ファイバのLP01モードとの結合効率が0.5以下である。 - 請求項7に記載の光伝送路において、
前記第2光ファイバおよび前記第3光ファイバそれぞれが、汎用シングルモード光ファイバであり、
前記第1光ファイバおよび前記汎用シングルモード光ファイバそれぞれの波長1310nmにおけるモードフィールド径の差が1μm以下である。 - 請求項10に記載の光伝送路において、
前記第2光ファイバが、汎用シングルモード光ファイバであり、
前記第1光ファイバと前記汎用シングルモード光ファイバとの接続において、前記第1光ファイバのLP11モードと前記汎用シングルモード光ファイバのLP01モードとの結合効率が0.5以下である。 - 請求項10に記載の光伝送路において、
前記第2光ファイバが、汎用シングルモード光ファイバであり、
前記第1光ファイバおよび前記汎用シングルモード光ファイバそれぞれの波長1310nmにおけるモードフィールド径の差が1μm以下である。
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CN2012800033911A CN103168262A (zh) | 2011-09-21 | 2012-09-10 | 光传输线 |
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EP (1) | EP2573599A3 (ja) |
JP (1) | JP2013068747A (ja) |
KR (1) | KR20140068851A (ja) |
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US9075212B2 (en) * | 2013-09-24 | 2015-07-07 | Corning Optical Communications LLC | Stretchable fiber optic cable |
CN106033998B (zh) * | 2015-03-16 | 2018-08-21 | 华为技术有限公司 | 一种检测多径干涉的方法及装置 |
JP7214352B2 (ja) * | 2018-03-08 | 2023-01-30 | 古河電気工業株式会社 | 光ファイバ |
GB202215027D0 (en) * | 2022-10-12 | 2022-11-23 | Lumenisity Ltd | Hollow core optical fibre transmission link |
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CN103168262A (zh) | 2013-06-19 |
US20130094819A1 (en) | 2013-04-18 |
RU2014101765A (ru) | 2015-10-27 |
EP2573599A2 (en) | 2013-03-27 |
EP2573599A3 (en) | 2013-04-10 |
KR20140068851A (ko) | 2014-06-09 |
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