WO2023145862A1 - 偏波保持ファイバ - Google Patents

偏波保持ファイバ Download PDF

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Publication number
WO2023145862A1
WO2023145862A1 PCT/JP2023/002603 JP2023002603W WO2023145862A1 WO 2023145862 A1 WO2023145862 A1 WO 2023145862A1 JP 2023002603 W JP2023002603 W JP 2023002603W WO 2023145862 A1 WO2023145862 A1 WO 2023145862A1
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Prior art keywords
polarization
maintaining fiber
stress
wavelength
less
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English (en)
French (fr)
Japanese (ja)
Inventor
義一 佐々木
和幸 林
昌一郎 松尾
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Fujikura Ltd
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Fujikura Ltd
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Priority to CN202380018971.6A priority Critical patent/CN118575109A/zh
Priority to US18/834,333 priority patent/US20250130363A1/en
Priority to JP2023577009A priority patent/JPWO2023145862A1/ja
Publication of WO2023145862A1 publication Critical patent/WO2023145862A1/ja
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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
    • G02B6/024—Optical fibres with cladding with or without a coating with polarisation maintaining properties
    • 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
    • G02B6/02004—Optical fibres with cladding with or without a coating characterised by the core effective area or mode field radius
    • 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
    • G02B6/02—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
    • G02B6/03694—Multiple layers differing in properties other than the refractive index, e.g. attenuation, diffusion, stress properties

Definitions

  • the present invention relates to a polarization-maintaining fiber provided with a pair of stress-applying portions.
  • Optical digital coherent communication has become widely used in order to respond to the increase in optical communication capacity accompanying the spread of smartphones and the diversification of data services. Also, recently, it is being considered to further increase the capacity of optical digital coherent communication by increasing the number of optical transceivers used for optical digital coherent communication.
  • Polarization-maintaining fiber is used to connect devices that perform optical digital coherent communication.
  • Patent Document 1 can be cited.
  • the optical transceivers In order to increase the number of optical transceivers, it is preferable to downsize the optical transceivers.
  • a polarization-maintaining fiber When a polarization-maintaining fiber is accommodated in a small optical transceiver, it becomes necessary to bend the polarization-maintaining fiber with a small bending radius, which leads to deterioration in communication quality due to an increase in bending loss. Further, when the polarization maintaining fiber is accommodated in a small optical transceiver, the polarization maintaining fiber may be twisted as well as bent.
  • the inventors studied the bending loss of polarization-maintaining fibers to which twist was applied. As a result, it was found that the twisted polarization-maintaining fiber has an extremely large bending loss compared to the non-twisted polarization-maintaining fiber.
  • One aspect of the present invention has been made in view of the above problems, and an object of the present invention is to reduce bending loss even if a degree of torsion that may occur when being accommodated in an optical transceiver or when being applied to a sensor is applied. To realize a polarization-maintaining fiber capable of suppressing to a level capable of withstanding normal use.
  • a polarization-maintaining fiber according to aspect 1 of the present invention comprises a core, a pair of stress-applying portions disposed on both sides of the core, and a clad enclosing the core and the pair of stress-applying portions, and
  • the cutoff wavelength is 1.41 ⁇ m or more and less than 1.55 ⁇ m when the length is 2 m and the bending radius is 140 mm.
  • the bending loss at 0.55 ⁇ m is 7 dB or less.
  • bending loss can be suppressed to a level that can withstand normal use, even if a twist that can occur when housing in an optical transceiver or when applying to a sensor is applied.
  • polarization-maintaining fiber can be realized.
  • FIG. 1A is a cross-sectional view showing a cross-section of a polarization maintaining fiber according to an embodiment of the present invention
  • FIG. (b) is a graph showing the refractive index distribution along the line AA' of the cross section shown in (a) of the polarization-maintaining fiber.
  • FIG. 1(a) is a cross-sectional view showing a cross section of the polarization-maintaining fiber 1.
  • FIG. (b) of FIG. 1 is a graph showing the refractive index distribution of the polarization maintaining fiber 1 along the line AA' of the cross section shown in (a) of FIG.
  • the cross section refers to a cross section perpendicular to the central axis of the polarization maintaining fiber 1 .
  • the polarization-maintaining fiber 1 includes a core 11, a pair of stress applying portions 12a and 12b arranged on both sides of the core 11, and a core 11 and a pair of stress applying portions 12a and 12b. and a clad 13 containing 12b.
  • the polarization-maintaining fiber 1 may have a coating that covers the clad 13 .
  • the polarization maintaining fiber 1 is also called a PANDA (Polarization-maintaining AND Absorption-reducing) fiber.
  • the core 11 is a columnar region extending in the central axis direction of the polarization maintaining fiber 1 .
  • the core refractive index n11 is higher than the clad 13 refractive index n13.
  • the core 11 is made of, for example, silica glass doped with an updopant. Examples of the updopant added to the core 11 include germanium (Ge).
  • the cross-sectional shape of the core 11 is circular.
  • the cross-sectional shape of the core 11 is not limited to this.
  • the cross-sectional shape of core 11 may be oval, crescent, or non-circular, for example.
  • the cross-sectional shape of the core 11 refers to the cross-sectional shape of the core 11 perpendicular to the central axis of the polarization-maintaining fiber 1 .
  • the stress-applying portions 12 a and 12 b are columnar regions extending in the central axis direction of the polarization maintaining fiber 1 .
  • the refractive index n12 of the stress applying portions 12a and 12b is lower than the refractive index n13 of the clad.
  • the stress-applying portions 12a and 12b are made of silica glass to which a down dopant is added, for example. Boron (B) and fluorine (F) are examples of down dopants added to the stress applying portions 12a and 12b.
  • the cross-sectional shape of the stress-applying portions 12a and 12b is circular (illustrated by solid lines) or elliptical (illustrated by dotted lines) whose short axis direction is the direction in which the stress-applying portions 12a and 12b are arranged.
  • the cross-sectional shapes of the stress applying portions 12a and 12b are not limited to these.
  • the cross-sectional shape of the stress applying portions 12a, 12b may be, for example, crescent-shaped or non-circular.
  • the cross-sectional shape of the stress-applying portions 12a and 12b refers to the shape of the cross-section orthogonal to the central axis of the polarization maintaining fiber 1 among the cross-sections of the stress-applying portions 12a and 12b.
  • the stress applying portions 12a and 12b are separated from the core 11 respectively.
  • the polarization-maintaining fiber 1 that satisfies Condition 2 or Condition 3, which will be described later.
  • the core 11 undergoes unexpected deformation due to the stress from the stress-applying portions 12a and 12b.
  • the transmission loss deteriorates due to material mismatch.
  • the core 11 is spaced apart from the stress-applying portions 12a and 12b, it is possible to suppress deterioration of transmission loss due to structural mismatch.
  • the cladding 13 is a columnar region extending in the central axis direction of the polarization maintaining fiber 1 .
  • the refractive index n13 of the clad 13 is lower than the refractive index n11 of the core 11 and higher than the refractive index n12 of the stress applying portions 12a and 12b.
  • the clad 13 is made of quartz glass, for example.
  • the cross-sectional shape of the clad 13 is circular.
  • the cross-sectional shape of the clad 13 is not limited to this.
  • the cross-sectional shape of the cladding 13 may be oval, crescent, or non-circular, for example.
  • the cross-sectional shape of the clad 13 refers to the cross-sectional shape of the clad 13 perpendicular to the central axis of the polarization-maintaining fiber 1 .
  • the clad diameter is preferably 80 ⁇ m or less.
  • the installation area when it is accommodated in an optical transceiver or when it is applied to a sensor, so high-density mounting can be achieved. Since the rigidity can be kept small, it is possible to reduce the deterioration of the mechanical strength of the polarization-maintaining fiber 1 when it is twisted.
  • a feature of the polarization-maintaining fiber 1 according to this embodiment is that it satisfies Condition 1 below.
  • the bending loss is 7 dB or less at a wavelength of 1.55 ⁇ m when the bending radius is 5 mm and the twist per fiber length of 31.4 mm (per turn, or approximately per turn) is one turn.
  • the bending loss of the polarization-maintaining fiber 1 can be suppressed to a level that can withstand normal use.
  • the degree of twisting that can occur in normal use is, for example, twisting that occurs when the polarization maintaining fiber 1 is accommodated in a housing of an optical transceiver or when the polarization maintaining fiber 1 is applied to a sensor. be.
  • the bending loss that can withstand normal use is, for example, bending loss that does not impair information superimposed on signal light in optical communication using the polarization maintaining fiber 1 .
  • the above bending loss can be any value of 7 dB or less. Therefore, for example, from the polarization-maintaining fiber 1 that satisfies Condition 1, to the polarization-maintaining fiber 1 whose bending loss is a specific numerical value, or the polarization-maintaining fiber 1 whose bending loss is within a specific numerical range, , are also included in the scope of disclosure of the specification of the present application as the polarization maintaining fiber 1 having the above effects.
  • the bending loss when twisting the polarization-maintaining fiber 1 tends to be minimized at the cut-off wavelength. Therefore, by bringing the cut-off wavelength closer to the working wavelength (1.55 ⁇ m in this embodiment), the amount of light leaking from the core 11 to the clad 13 when twisting and bending occurs can be suppressed. Also, by making the cut-off wavelength smaller than the working wavelength, it is possible to realize single-mode transmission at the working wavelength. Focusing on these points, the inventors of the present application have found that when the cut-off wavelength satisfies the following condition 1a, the bending loss when twisting satisfies the above condition 1, and single-mode transmission at the working wavelength is possible. We have found that the polarization maintaining fiber 1 can be realized.
  • the cutoff wavelength is 1.41 ⁇ m or more and less than 1.55 ⁇ m when the fiber length is 2 m and the bending radius is 140 mm.
  • the cut-off wavelength can be any value between 1.41 ⁇ m and less than 1.55 ⁇ m. Therefore, for example, from the polarization-maintaining fiber 1 satisfying the conditions 1 and 1a, to the polarization-maintaining fiber 1 having the cut-off wavelength of a specific value, or the polarization-maintaining fiber having the cut-off wavelength within a specific numerical range, 1 is also included in the scope of disclosure of this specification as the polarization maintaining fiber 1 that satisfies condition 1 above.
  • the cut-off wavelength may shift to the longer wavelength side due to lateral pressure on the polarization-maintaining fiber 1 (for example, lateral pressure caused by deterioration of the resin coating covering the side surface of the polarization-maintaining fiber 1) or disturbance.
  • lateral pressure on the polarization-maintaining fiber 1 for example, lateral pressure caused by deterioration of the resin coating covering the side surface of the polarization-maintaining fiber 1
  • disturbance for example, lateral pressure caused by deterioration of the resin coating covering the side surface of the polarization-maintaining fiber 1
  • the cut-off wavelength may shift to the longer wavelength side due to lateral pressure or disturbance.
  • the lower limit of the cut-off wavelength is set to 1.41 ⁇ m, even if the cut-off wavelength shifts to the long wavelength side due to the side pressure or disturbance, the cut-off wavelength is prevented from exceeding the working wavelength. Therefore, it is possible to further reduce the possibility of difficulty in single-mode transmission at the wavelength used.
  • the polarization-maintaining fiber 1 in which the relative refractive index difference of the core 11 with respect to the clad 13 is large can suppress the bending loss when torsion is applied. Therefore, when the relative refractive index difference of the core 11 with respect to the clad 13 satisfies the following condition 1b, the above condition 1 can be satisfied more reliably.
  • Condition 1b The relative refractive index difference of the core 11 with respect to the clad 13 is 0.36% or more.
  • a small mode field diameter at the wavelength used (1.55 ⁇ m in this embodiment) means that light propagating through the core 11 is strongly confined in the core 11 . Therefore, the polarization-maintaining fiber 1 having a smaller mode field diameter at the wavelength used can suppress bending loss when twisted. Therefore, when the mode field diameter at the working wavelength satisfies the following condition 1c, it becomes possible to satisfy the above condition 1 more reliably.
  • Condition 1c The mode field diameter at a wavelength of 1.55 ⁇ m is 9.2 ⁇ m or less.
  • the relative refractive index difference may be any value of 0.36% or more. Therefore, for example, from the polarization-maintaining fiber 1 satisfying the above conditions 1a, 1b, and 1c, to the polarization-maintaining fiber 1 having the specific value of the relative refractive index difference, or the specific numerical range of the relative refractive index difference.
  • the polarization-maintaining fiber 1 that satisfies Condition 1 above is also included in the scope of disclosure of the present specification.
  • the mode field diameter can be any value of 9.2 ⁇ m or less. Therefore, for example, from the polarization-maintaining fiber 1 that satisfies the above conditions 1a, 1b, and 1c, the polarization-maintaining fiber whose mode field diameter is a specific numerical value or whose mode field diameter is within a specific numerical range 1 is also included in the scope of disclosure of this specification as the polarization maintaining fiber 1 that satisfies condition 1 above.
  • Table 1 shows (1) the bending loss when 10 turns are wound around a mandrel with a radius of 5 mm without twisting, and (2) per fiber length of 31.4 mm for seven types of polarization-maintaining fibers A to G. This is the result of measurement of bending loss when twisted by one turn (360°) and wound 10 times around a mandrel with a radius of 5 mm.
  • Table 1 also shows the working wavelength, the cutoff wavelength, the mode field diameter, the clad diameter, and the relative refractive index difference as parameters that have a particularly dominant effect on the bending loss.
  • the cutoff wavelength is the cutoff wavelength when the fiber length is 2 m and the bending radius is 140 mm.
  • the mode field diameter is the mode field diameter at a wavelength of 1.55 ⁇ m (used wavelength).
  • the relative refractive index difference is the relative refractive index difference of the core with respect to the clad.
  • polarization-maintaining fibers A to E satisfy the above conditions 1 and 1a.
  • polarization-maintaining fibers A-E are examples.
  • the polarization-maintaining fibers F to G do not satisfy Condition 1 described above. Therefore, the polarization-maintaining fibers F to G are comparative examples.
  • the relative refractive index difference was 0.36% or more.
  • the relative refractive index difference was less than 0.36%. Therefore, it was confirmed that the relative refractive index difference preferably satisfies the above condition 1b in order for the polarization-maintaining fiber to satisfy the above condition 1.
  • the relative refractive index difference was 0.55% or less.
  • the relative refractive index difference preferably satisfies Condition 1b' below.
  • the effective condition for reducing the bending loss when torsion is applied is that the relative refractive index difference is 0.36% or more, and that the relative refractive index difference is 0.55% or less. , is not essential to satisfy condition 1.
  • Condition 1b' The relative refractive index difference of the core 11 with respect to the clad 13 is 0.36% or more and 0.55% or less.
  • the mode field diameter was 9.2 ⁇ m or less.
  • the mode field diameter was larger than 9.2 ⁇ m. Therefore, in order for the polarization-maintaining fiber to satisfy Condition 1 above, it was confirmed that the mode field diameter preferably satisfies Condition 1c above.
  • the mode field diameter was 8.0 ⁇ m or more.
  • the mode field diameter preferably satisfies Condition 1c' below.
  • the condition effective for reducing the bending loss when torsion is applied is that the mode field diameter is 9.2 ⁇ m or less, and that the mode field diameter is 8.0 ⁇ m or more is the condition 1. not required for fulfillment.
  • Condition 1c' The mode field diameter at a wavelength of 1.55 ⁇ m is 8.0 ⁇ m or more and 9.2 ⁇ m or less.
  • a light source such as a tunable laser that can be used for optical transceivers and sensors typically has an emitted light diameter of 8.0 ⁇ m or more and 9.5 ⁇ m or less in the 1.55 ⁇ m band, for example.
  • the polarization-maintaining fiber 1 satisfies the condition 1c', the difference between the exit light diameter of such a light source and the mode field diameter of the polarization-maintaining fiber 1 can be kept small. Therefore, a polarization-maintaining fiber that satisfies condition 1c' above has the additional advantage that connection loss can be small when connecting with such a light source.
  • the mode field diameter tends to increase. Therefore, in the case of a polarization-maintaining fiber that satisfies the above condition 1c′, the connection loss between the light source and the polarization-maintaining fiber is reduced to can be suppressed. Moreover, when the value of 0.55% or less is satisfied in the above condition 1b', the mode field diameter tends to increase. Therefore, in the case of a polarization-maintaining fiber that satisfies the above condition 1b′, the connection loss between the light source and the polarization-maintaining fiber is reduced to can be suppressed.
  • Table 2 shows, for the polarization-maintaining fibers A to F shown in Table 1, (1) polarization crosstalk at a wavelength of 1.55 ⁇ m without twisting or bending, and (2) polarization-maintaining fibers with a radius of 5 mm without twisting. (3) Polarization crosstalk at a wavelength of 1.55 ⁇ m when the mandrel is wound 10 times, (3) when a fiber length of 31.4 mm is twisted by 1 rotation (360°) and the mandrel is wound 10 times with a radius of 5 mm. (4) Polarization crosstalk at 1.55 ⁇ m wavelength and 1 turn per 31.4 mm fiber length for 10 turns on a 5 mm radius mandrel without twisting. 10 shows the result of measurement of the ratio of the polarization crosstalk at a wavelength of 1.55 ⁇ m when the wire is twisted 10 times around a mandrel with a radius of 5 mm.
  • parameters that have a particularly dominant effect on polarization crosstalk include the wavelength used, the cladding diameter b, the mode field diameter d, the stress-applied portion diameter t, the stress-applied portion spacing a, normalization It is a table listing stress-applied portion intervals 2a/d, normalized stress-applied portion diameters t/b, and stress-applied portion non-circularity.
  • the stress-applying portion interval a is half the shortest distance between the two stress-applying portions 12a and 12b.
  • the diameter t of the stress-applying portion is the diameter of the circle
  • the stress-applying portions 12a and 12b are elliptical
  • the length of the minor axis of the ellipse short (twice the shaft radius)
  • the length of the major axis twice the major axis radius
  • the length of the major axis may be the stress applying portion diameter t.
  • the stress-applying portion diameter t is the length of the minor axis of the imaginary ellipse circumscribing the shape (2 times).
  • the noncircularity of the stressed portion is the quotient obtained by dividing the difference between the length of the major axis and the length of the minor axis by the diameter t of the stressed portion when the stressed portions 12a and 12b are oval.
  • the normalized stress-applied portion interval 2a/d is a value obtained by normalizing twice the stress-applied portion interval a by the mode field diameter d, that is, twice the stress-applied portion interval a divided by the mode field diameter d. is a quotient.
  • the normalized stress-applied portion spacing is sometimes defined as a value obtained by normalizing twice the stress-applied portion spacing a by the core diameter, but in this specification, the mode field diameter is Considering that it is an influential parameter, it is defined as a value normalized by the mode field diameter d, which is twice the stress applying portion interval a. Since the mode field diameter is strongly correlated with the core diameter, it is permissible to adopt the definition herein.
  • the normalized stress-applying portion diameter t/b is the value obtained by normalizing the stress-applying portion diameter t by the clad diameter b, that is, the quotient obtained by dividing the stress-applying portion diameter t by the clad diameter b.
  • the polarization-maintaining fibers A to E according to the example satisfy the following condition 3. If the following condition 3 is satisfied, even if the polarization maintaining fiber 1 is twisted to a degree that can occur in normal use, the polarization crosstalk of the polarization maintaining fiber 1 can be suppressed to a level that can withstand normal use. It has the effect of being able to
  • Condition 3 Polarization crosstalk at a wavelength of 1.55 ⁇ m when the bending radius is 5 mm and no twisting occurs, and wavelength 1 when the bending radius is 5 mm and the twist is one rotation per fiber length of 31.4 mm. It can be seen that the ratio to polarization crosstalk at 55 ⁇ m is 1.26 or less.
  • the normalized stress applying portion interval 2a/d was 1.091 or more and 1.226 or less. Therefore, in order for the polarization-maintaining fiber to satisfy Condition 2 or Condition 3 above, it was found that the normalized stress-applying portion interval 2a/d is preferably 1.091 or more and 1.226 or less.
  • the normalized stress-applied portion diameter t/b was 0.281 or more and 0.319 or less in the polarization-maintaining fibers A to E according to the example. Therefore, in order for the polarization-maintaining fiber to satisfy Condition 2 or Condition 3 above, it was found that the normalized stress-applying portion diameter t/b is preferably 0.281 or more and 0.319 or less.
  • the non-circularity of the stress applying portions 12a and 12b was 4.2% or more and 4.5% or less. Therefore, it was found that the non-circularity of the stress-applying portions 12a and 12b is preferably 4.2% or more and 4.5% or less in order for the polarization-maintaining fiber to satisfy Condition 2 or Condition 3 above. .
  • a polarization-maintaining fiber according to aspect 1 of the present invention comprises a core, a pair of stress-applying portions disposed on both sides of the core, and a clad enclosing the core and the pair of stress-applying portions, and
  • the cutoff wavelength is 1.41 ⁇ m or more and less than 1.55 ⁇ m when the length is 2 m and the bending radius is 140 mm.
  • the bending loss at 0.55 ⁇ m is 7 dB or less.
  • the relative refractive index difference of the core with respect to the clad is 0.36% or more, and the mode field diameter at a wavelength of 1.55 ⁇ m is A configuration is adopted in which the thickness is 9.2 ⁇ m or less.
  • the relative refractive index difference of the core with respect to the clad is 0.36% or more and 0.55% or less, and the wavelength is 1.55 ⁇ m.
  • a mode field diameter of 8.0 ⁇ m or more and 9.2 ⁇ m or less is employed.
  • the polarization-maintaining fiber according to aspect 4 of the present invention in addition to the configuration of aspects 1 to 3, at a wavelength of 1.55 ⁇ m when the bending radius is 5 mm and the twist per fiber length of 31.4 mm is 1 rotation A configuration is adopted in which the polarization crosstalk is -25 dB or less.
  • polarization-maintaining fiber according to aspect 5 of the present invention in addition to the configuration of any one of aspects 1 to 4, polarization crosstalk at a wavelength of 1.55 ⁇ m when the bending radius is 5 mm and twist is eliminated, A configuration is adopted in which the ratio of polarization crosstalk at a wavelength of 1.55 ⁇ m is 1.26 or less when the bending radius is 5 mm and the twist per fiber length of 31.4 mm is one rotation.
  • the cross section of each of the pair of stress-applying parts in addition to the configuration of any one of aspects 1 to 5, in the cross section of each of the pair of stress-applying parts, the cross section is an ellipse with the short axis direction being the direction in which the pair of stress applying portions are arranged, and the non-circularity thereof is 4.2% or more and 4.5% or less.
  • polarization-maintaining fiber according to aspect 7 of the present invention in addition to the configuration of any one of aspects 1 to 6, a configuration is adopted in which the pair of stress-applying portions are separated from the core. ing.
  • polarization-maintaining fiber according to aspect 8 of the present invention in addition to the configuration of any one of aspects 1 to 7, a regular A configuration is adopted in which the stress-applying portion interval 2a/d is 1.091 or more and 1.226 or less.
  • a normalized stress-applying portion diameter t/b obtained by normalizing the stress-applying portion diameter t by the cladding diameter b is A configuration of 0.281 or more and 0.319 or less is adopted.
  • a configuration is adopted in which the clad diameter of the clad is 80 ⁇ m or less.

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  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
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PCT/JP2023/002603 2022-01-31 2023-01-27 偏波保持ファイバ Ceased WO2023145862A1 (ja)

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WO2025159182A1 (ja) * 2024-01-26 2025-07-31 株式会社フジクラ 偏波保持ファイバ

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WO2025159182A1 (ja) * 2024-01-26 2025-07-31 株式会社フジクラ 偏波保持ファイバ

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