JP5743157B2 - Cut-off wavelength control type optical fiber and optical fiber cable - Google Patents

Description

  The present invention relates to a technique for realizing a reduction in bending loss and an increase in MFD while suppressing an increase in cut-off wavelength in a single mode optical fiber and an optical fiber cable used for single mode optical communication.

  With the progress of Fiber To The Home (FTTH), technology for improving the efficiency of construction, maintenance and operation of optical line facilities is becoming more and more important. In recent years, optical fibers with reduced bending loss even for small bending diameters have been developed and put to practical use for indoor wiring and the like (for example, see Non-Patent Document 1).

On the other hand, it is known that in the optical transmission system, when the input power increases, the transmission characteristics deteriorate due to the optical nonlinear effect. In order to suppress the optical nonlinear effect, it is effective to increase the effective area (A _eff ) of the optical fiber. Since A _eff has a correlation with the mode field diameter (MFD), the expansion of A _eff can also be realized by increasing the MFD. For this reason, single mode optical fibers with an expanded MFD have been studied by optimizing the refractive index distribution of the core of the optical fiber (see, for example, Non-Patent Documents 2 and 3).

However, the reduction of the bending loss α _b and the expansion of the MFD are in a trade-off relationship with the cutoff wavelength λ _c . For this reason, when the bending loss is reduced or the MFD is expanded while the outer diameter of the cladding of the optical fiber is kept constant, there is a problem that the cutoff wavelength becomes longer than desired characteristics.

  More specifically, using a step-type simple refractive index distribution, the outer diameter of the cladding is 125 μm, the MFD at the cutoff wavelength and the wavelength of 1310 nm is equivalent to the conventional 1.3 μm band zero-dispersion single mode optical fiber (SMF). It was difficult to reduce the bending loss to 0.1 dB / 10 or less when measured under the conditions of 8.6 μm or more, a wavelength of 1625 nm, and a bending radius of 15 mm.

  Similarly, when using a step-type refractive index profile, the cladding has an outer diameter of 125 μm, a cutoff wavelength of 1530 nm or less, a wavelength of 1625 nm, a bending radius of 30 mm, and a bending loss of 0.1 dB / 100 or less. In addition, it was difficult to set the MFD at a wavelength of 1310 nm to about 13.5 μm or more.

  Therefore, Non-Patent Document 1 realizes desired cutoff wavelength characteristics, MFD characteristics, and bending loss characteristics by multilayering and controlling the refractive index distribution of the core of the optical fiber in more detail.

Similarly, regarding the expansion of A _eff , for example, in Non-Patent Document 3, by optimizing the refractive index distribution of the core of the optical fiber, the cut-off wavelength is set to 1460 nm or less, and the A _eff of the wavelength 1550 nm is reduced to about 160 μm ^2. Expanding techniques are disclosed. However, these A _eff expansion optical fibers have a problem that it is necessary to make the refractive index distribution multilayer and to precisely control the refractive index distribution.

  Therefore, there is a need for a technique that can simultaneously realize a reduction in bending loss and an increase in MFD while suppressing an increase in cutoff wavelength.

  In the cut-off wavelength control type optical fiber of the present invention, by appropriately controlling the normalized frequency V of the core of the optical fiber and suitably controlling the outer diameter D of the clad within a range smaller than 125 μm, the wavelength 1625 nm, A bending loss characteristic of 0.1 dB / 100 or less at a bending radius of 30 mm, an MFD characteristic of 8.6 μm or more at a wavelength of 1310 nm, and a desired cutoff wavelength characteristic are realized at the same time.

  More specifically, the cutoff wavelength control type optical fiber of the present invention has a structure having a clad having a uniform refractive index and a core having a higher refractive index than the clad, and the outer diameter of the clad of the optical fiber. The relationship between D and the normalized frequency V of the core is

The above-described problem is solved by controlling to satisfy the above.

Here, c ₁ and c ₂ are coefficients expressed by a function of the outer diameter D of the cladding, and the normalized frequency V of the core is the core diameter 2a, the relative refractive index difference Δ, and the core Using refractive index n ₁

Is described by

  More specifically, the cutoff wavelength control type optical fiber of the present invention has a normalized frequency V at a core wavelength of 1550 nm in a range from 2.00 to 3.35, and an outer diameter D of a cladding in a range from 50 to 119 μm. By controlling so as to satisfy the formula (1), the cutoff wavelength of the optical fiber is shortened by 30 nm or more from the cutoff wavelength when the outer diameter D of the cladding is 125 μm.

  More specifically, the cutoff wavelength control type optical fiber of the present invention has a normalized frequency V at a core wavelength of 1550 nm in the range from 2.25 to 2.45, and an outer diameter D of the cladding in the range from 81 to 104 μm. By controlling so as to satisfy the above formula (1), the cutoff wavelength of the optical fiber is 1260 nm or less, the MFD at the wavelength 1310 nm is 8.6 to 10.3 μm, and the wavelength is 1625 nm and the bending radius is 30 mm, 0.1 dB / 100 windings. The following bending loss characteristics are realized.

  Further, by controlling the normalized frequency V of the core in the range of 2.68 to 3.10 and the outer diameter D of the cladding in the range of 67 to 100 μm so as to satisfy the above equation (1), The cutoff wavelength is 1530 nm or less, the MFD at a wavelength of 1310 nm is 8.6 to 14.1 μm, and the bending loss at a wavelength of 1625 nm and a bending radius of 30 mm is 0.1 dB / 100 or less.

  According to the cut-off wavelength control of the present invention, it is possible to realize an optical fiber and an optical fiber cable that suppress the lengthening of the cut-off wavelength and have desired bending loss characteristics and mode field diameter characteristics. Further, the reduction of the outer diameter of the clad also has the effect of making it possible to improve the spatial multiplicity of the optical transmission medium.

It is a conceptual diagram which shows an example of the cross-section of the cutoff wavelength control type | mold optical fiber of this invention. It is a figure which shows an example of the relationship between the outer diameter D of the clad | crud in the cutoff wavelength control type | mold optical fiber of this invention, and the confinement loss of a fundamental mode and a higher mode. It is a figure which shows an example of the relationship between the outer diameter D of the clad in the cutoff wavelength control type optical fiber of this invention, and the confinement loss difference between a fundamental mode and a higher mode. It is a figure which shows an example of the relationship between the outer diameter D of a clad in the cutoff wavelength control type | mold optical fiber of this invention, and cutoff wavelength (lambda) _c . It is the figure which showed the outer diameter D of the clad as a parameter about the relationship between the cutoff wavelength λ _c and the normalized frequency V in the cutoff wavelength control type optical fiber of the present invention. FIG. 5 is a graph showing the relationship between the normalized frequency V and the outer diameter D of the cladding in the cutoff wavelength control type optical fiber of the present invention, with the amount of change Δλ _c relative to the cutoff wavelength when the outer diameter D of the cladding is 125 μm as a parameter. It is. In the cut-off wavelength control type optical fiber of the present invention, it is a diagram showing the structural conditions of the core radius a and relative refractive index difference Δ with a cut-off wavelength of 1260 nm. In the cutoff wavelength control type optical fiber of this invention, it is a figure which shows the structural conditions of the radius a of a core which makes a cutoff wavelength 1530nm, and relative refractive index difference (DELTA).

  Hereinafter, embodiments of a cutoff wavelength control type optical fiber of the present invention will be described with reference to the drawings.

  FIG. 1 is a conceptual diagram showing a cross-sectional structure of a cutoff wavelength control type optical fiber of the present invention. The cutoff wavelength control type optical fiber of the present invention comprises a clad 1 having a uniform refractive index and a core 2 having a higher refractive index than the clad 1 and disposed in the center of the clad 1. Here, the diameter of the core is defined as 2a, and the outer diameter of the cladding is defined as D.

Hereinafter, a case where the core 2 has a step type refractive index distribution in which the relative refractive index difference with respect to the cladding 1 is Δ will be described. Incidentally, delta is the refractive index n ₁ of the core 2, with a refractive index n ₂ of the cladding 1

Defined by

  FIG. 2 is a diagram showing the relationship between the outer diameter D of the cladding 1 and the confinement loss of the fundamental mode and higher-order mode at a wavelength of 1250 nm in the cutoff wavelength control type optical fiber of the present invention. In FIG. 2, as an example, the radius a of the core 2 is 4.5 μm, the relative refractive index difference Δ is 0.4%, the mode field diameter MFD (2 W) at a wavelength of 1310 nm in the core structure is 9.0 μm, and the outer diameter D of the cladding 1 is The cutoff wavelength at 125 μm is 1350 nm.

  FIG. 2 shows that the confinement loss increases as the outer diameter D of the cladding 1 decreases. It can also be seen that the increase in the confinement loss due to the decrease in the outer diameter D of the cladding 1 is larger in the higher order mode indicated by the broken line than in the fundamental mode indicated by the solid line.

  FIG. 3 is a diagram showing the relationship between the outer diameter D of the cladding 1 and the confinement loss difference between the fundamental mode and the higher order mode in the cutoff wavelength control type optical fiber of the present invention. The vertical axis represents the confinement loss difference per 22 m. The calculation wavelength is 1250 nm, and the radius a and the relative refractive index difference Δ of the core 2 are the same as those in the calculation example of FIG.

  FIG. 3 shows that the confinement loss difference increases as the outer diameter D of the cladding 1 decreases. In Non-Patent Document 4, the cutoff wavelength is defined as a wavelength at which the loss difference between the fundamental mode and the higher-order mode is 0.1 dB or more at 22 m. FIG. 3 shows that when the outer diameter D of the cladding 1 is 62 μm, the confinement loss difference per 22 m is 0.1 dB. Therefore, in the calculation example of FIG. 3, the cut-off wavelength can be shortened from 1350 nm to 1250 nm by reducing the outer diameter D of the cladding 1 from 125 μm to 62 μm.

FIG. 4 is a drawing showing an example of the relationship between the outer diameter D of the cladding 1 and the cutoff wavelength λ _{c in} the cutoff wavelength control type optical fiber of the present invention. The solid line and plot in the figure are the calculation result and the measurement result, respectively, and represent the cutoff wavelength characteristic at a length of 5 km. The radius a of the core 2 is 4.1 μm, the relative refractive index difference Δ is 0.38%, and the normalized frequency V at a wavelength of 1550 nm is 2.10. Incidentally, the normalized frequency V is the radius a of the core 2, the relative refractive index difference delta, and using the refractive index n ₁ of the core 2 is defined by equation (2). From FIG. 4, it can be confirmed that the calculation result and the measurement result are in good agreement.

FIG. 5 is a diagram showing the relationship between the cutoff wavelength λ _c and the normalized frequency V in the cutoff wavelength control type optical fiber of the present invention, with the outer diameter D of the cladding 1 as a parameter. A solid line, a broken line, and an alternate long and short dash line in the figure indicate calculation results when the outer diameter D of the cladding 1 is 125, 100, and 50 μm, respectively. From FIG. 5, it can be seen that the relationship between the cutoff wavelength λ _c and the normalized frequency V at the outer diameter D of an arbitrary clad 1 can be described by a linear function represented by equation (1).

Here, c ₁ and c ₂ in the formula (1) are coefficients expressed as a function of the outer diameter D of the cladding 1, and c ₁ and c ₂ at a wavelength of 1550 nm in the embodiment of the present invention are respectively

Can be described by

  According to Non-Patent Document 5, the maximum tensile tension required for coating removal is defined as 8.9N. Generally, in order to satisfy the mechanical strength that can withstand a tensile tension of 8.9 N, the outer diameter D of the cladding 1 needs to be 50 μm or more.

From FIG. 5, in the cut-off wavelength control type optical fiber of the present invention, in order to set the cut-off wavelength λ _c to 1530 nm or less and the outer diameter D of the clad 1 to 50 μm or more, the normalized frequency V at the wavelength 1550 nm is set to It can be seen that it must be 3.35 or less.

  Further, according to Non-Patent Document 6, in a general-purpose 1.3 μm band zero-dispersion single mode optical fiber (SMF), the MFD at a wavelength of 1310 nm is 8.6 μm or more, and the bending loss at a wavelength of 1625 nm and a bending radius of 30 mm is increased. It is recommended that the volume be 0.1 dB / 100 or less. In the optical fiber having the step-type refractive index profile shown in FIG. 1, in order to realize the above-mentioned MFD and bending loss characteristics, V at a wavelength of 1550 nm needs to be 2.0 or more.

FIG. 6 shows a change Δλ with respect to the cutoff wavelength when the outer diameter D of the cladding 1 is 125 μm with respect to the relationship between the outer diameter D of the cladding 1 and the normalized frequency V in the cutoff wavelength control type optical fiber of the present invention. It is a figure which shows _c as a parameter. A shaded area in the figure indicates a range where the above-mentioned normalized frequency V and the minimum cladding outer diameter are satisfied, and Δλ _c is 30 nm or more.

  FIG. 6 shows that when the normalized frequency V at a wavelength of 1550 nm is 2.0 and the outer diameter D of the cladding is 100 μm, a change amount of the cutoff wavelength of 30 nm can be realized. Similarly, when the normalized frequency V is 3.35, it can be confirmed that an amount of change of 30 nm can be obtained by setting the outer diameter D of the cladding 1 to 119 μm or less. Furthermore, when V is 3.35 and the outer diameter D of the optical fiber is 50 μm, it can be seen that a change amount of the cutoff wavelength of 300 nm or more can be obtained.

  In the embodiment of the present invention, a core having a step type refractive index distribution has been described as an example. However, according to Non-Patent Document 7, the normalized frequency V of a core having an arbitrary refractive index distribution is equivalent. The normalized frequency T can be handled. Therefore, a core having an arbitrary refractive index distribution can be applied to the cutoff wavelength control type optical fiber of the present invention.

  As described above, according to the cutoff wavelength control type optical fiber of the present invention, the normalized frequency V of the core is in the range of 2.00 to 3.35, and the outer diameter D of the cladding is expressed by the equations (1), (4) and By using (5) to control within a suitable range of 50 μm or more, a cutoff wavelength characteristic of 1530 nm or less, a bending loss characteristic of 0.1 dB / 100 or less at a wavelength of 1625 nm and a bending radius of 30 mm, and a wavelength of 1310 nm A single mode optical fiber having an MFD characteristic of 8.6 μm or more can be realized.

  In the following, in the cut-off wavelength control type optical fiber of the present invention having the cross-sectional structure shown in FIG. 1, the cut-off wavelength is 1260 nm or less, the wavelength is 1625 nm, the bending loss is 30 dB or less at a bend radius of 30 mm, An embodiment in which the MFD at 1310 nm is set to 8.6 μm or more will be described with reference to the drawings.

  FIG. 7 is a drawing showing the structural conditions of the core radius a and the relative refractive index difference Δ in the cutoff wavelength control type optical fiber according to the first embodiment of the present invention.

The three solid lines in the figure indicate the structural conditions where the minimum cladding outer diameter is 80, 90, and 100 μm, respectively, and the minimum cladding outer diameter is the outer diameter of the cladding with a confinement loss of 10 ⁻⁴ dB / km at a wavelength of 1625 nm. Defined as

Also, the two broken lines in the figure indicate the bending loss characteristic conditions. By controlling the core radius a and the relative refractive index difference Δ in the region above the broken line, 0.1 dB / 100 at a wavelength of 1625 nm and a bending radius of 30 mm. It is possible to realize a bending loss characteristic of not more than a winding, or a bending loss characteristic of not more than 1.0 dB / 1 winding at a wavelength of 1625 nm and a bending radius of 7.5 mm. The one-dot chain line and the two-dot chain line indicate the zero dispersion wavelength λ ₀ and MFD (2W) conditions of the general-purpose SMF, respectively, and are recommended in Non-Patent Document 6 in the region surrounded by the two lines. Therefore, it is possible to realize zero dispersion wavelength characteristics from 1 to 1324 nm and MFD characteristics from 8.6 to 9.5 μm at a wavelength of 1310 nm.

Furthermore, λ _c125 indicated by a fine dotted line in the figure indicates a boundary where the cutoff wavelength becomes 1260 nm when the outer diameter D of the cladding is 125 μm. In the conventional SMF, the cutoff is in the lower area of the fine dotted line. Wavelength characteristics can be realized. On the other hand, a thick dotted line λ _c indicates a boundary where the outer diameter D of the cladding is controlled to 125 μm or less and the cutoff wavelength is 1260 nm in the cutoff wavelength control type optical fiber of the present invention.

  From FIG. 7, the core radius a and the relative refractive index difference Δ are shaded in the figure, that is, the core radius a is in the range from 4.20 to 5.15 μm, and the relative refractive index difference Δ is 0.275 to 0.450%. MFD characteristics of 8.6 μm or more at a wavelength of 1310 nm by controlling so that the normalized frequency V of the core and the outer diameter D of the cladding satisfy the expressions (1), (4) and (5) It can be seen that a bending loss characteristic of 0.1 dB / 100 or less at a wavelength of 1625 nm and a bending radius of 30 mm and a cutoff wavelength characteristic of 1260 nm or less can be realized simultaneously.

  The core radius a is in the range from 4.2 to 4.7 μm, the relative refractive index difference Δ is in the range from about 0.345 to 0.450%, and the cladding outer diameter D is in the range from 81 to 95 μm (1), By controlling so as to satisfy (4) and (5), the MFD and zero dispersion wavelength characteristics equivalent to the conventional SMF can also be satisfied.

Here, when the core radius a is in the range of 4.25 to 4.45 μm, the relative refractive index difference Δ is in the range of 0.425 to 0.450%, and the outer diameter D of the cladding is in the range of 81 to 85 μm, It is more preferable because the same characteristics can be realized and the bending loss α _b at a wavelength of 1625 nm and a bending radius of 7.5 mm can be improved to 1.0 dB / 1 turn or less. In addition, the core radius a is in the range from 4.60 to 5.15 μm, the relative refractive index difference Δ is in the range from 0.275 to 0.355%, and the outer diameter D of the cladding is in the range from 90 to 104 μm. By controlling to satisfy 4) and (5), the MFD at a wavelength of 1310 nm can be expanded from 9.5 to 10.3 μm.

  Here, when the core radius a is in the range of 4.6 to 4.9 μm, the relative refractive index difference Δ is in the range of 0.305 to 0.355%, and the outer diameter D of the cladding is in the range of 90 to 100 μm, It is more preferable because the same zero dispersion wavelength characteristic can be realized and the MFD at a wavelength of 1310 nm can be expanded from 9.5 to 10.0 μm.

  In the following, in the cut-off wavelength control type optical fiber of the present invention having the cross-sectional structure shown in FIG. 1, the cut-off wavelength is 1530 nm or less, the wavelength is 1625 nm, the bending loss is 30 dB or less at a bend radius of 30 mm, and the wavelength is An embodiment in which the MFD at 1310 nm is 8.6 to 14.1 μm will be described with reference to the drawings.

  FIG. 8 is a view showing the structural conditions of the core radius a and the relative refractive index difference Δ in the cutoff wavelength control type optical fiber according to the second embodiment of the present invention.

The four solid lines in the figure indicate the structural conditions where the minimum cladding outer diameter is 70, 80, 90, and 100 μm, respectively. The minimum cladding outer diameter is the cladding with a confinement loss of 10 ⁻⁴ dB / km at a wavelength of 1625 nm. Defined as outer diameter.

  The broken line in the figure indicates the bending loss characteristic condition. By controlling the core radius a and relative refractive index difference Δ in the region above the broken line, the wavelength is 1625 nm, the bending radius is 30 mm, and 0.1 dB / 100 windings or less. It is possible to realize the bending loss characteristics of The two-dot chain line indicates the MFD condition of general-purpose SMF, and it is possible to realize MFD characteristics of 8.6 to 9.5 μm at a wavelength of 1310 nm in the region surrounded by the two lines.

Furthermore, λ _c125 indicated by a fine dotted line in the figure shows a boundary where the cutoff wavelength becomes 1530 nm when the outer diameter D of the cladding is 125 μm. In the conventional SMF, the cut is shown in the lower area of the fine dotted line. It is possible to realize off-wavelength characteristics. On the other hand, a thick dotted line λ _c indicates a boundary where the outer diameter D of the cladding is controlled to 125 μm or less and the cutoff wavelength is 1530 nm in the cutoff wavelength control type optical fiber of the present invention.

  From FIG. 8, the core radius a and the relative refractive index difference Δ are shaded in the figure, ie, the core radius a is in the range of 4.6 to 7.1 μm, and the relative refractive index difference Δ is 0.230 to 0.575%. MFD that becomes 8.6 μm or more at a wavelength of 1310 nm by controlling so that the normalized frequency V of the core and the outer diameter D of the cladding satisfy the expressions (1), (4), and (5) It can be seen that a characteristic, a bending loss characteristic of a wavelength of 1625 nm, a bending radius of 30 mm, 0.1 dB / 100 or less, and a cutoff wavelength characteristic of 1530 nm or less can be realized simultaneously.

When the core radius a is in the range from 6.5 to 7.1 μm, the relative refractive index difference Δ is in the range from 0.230 to 0.270%, and the outer diameter D of the cladding is in the range from 93 to 100 μm, the cut is 1530 nm or less. The off-wavelength characteristics and the bending loss at a wavelength of 1625 nm and a bending radius of 30 mm are preferably 0.1 dB / 100 or less, and the MFD at a wavelength of 1310 nm can be expanded from 13.5 to a maximum of 14.1 μm. Here, the MFD at a wavelength of 1310 nm of 14.1 μm corresponds to A _eff at a wavelength of 1550 nm of 157 μm ² , and the effective area A _eff can be increased using a simple step-type refractive index distribution.

  As described above, according to the cutoff wavelength control type optical fiber of the present invention, the normalized frequency V of the core and the outer diameter D of the cladding are controlled using the equations (1), (4), and (5). By doing so, it becomes possible to simultaneously realize a cutoff wavelength of 1530 nm or less, a bending loss of 0.1 dB / 100 or less at a wavelength of 1625 nm, a bending radius of 30 mm, and an MFD characteristic of 8.6 μm or more at a wavelength of 1310 nm. More specifically, the cutoff wavelength is 1260 nm or less, the bending loss is 1625 nm, the bending radius is 30 mm, 0.1 dB / 100 or less, the zero dispersion wavelength is 1300 to 1324 nm, which is equivalent to the conventional SMF, and the wavelength is 1310 nm. The MFD can be expanded up to 10.3 μm.

  In addition, the cut-off wavelength is 1260 nm or less, the MFD is 1310 nm, the wavelength is 8.6 to 9.5 μm, the zero-dispersion wavelength is 1300 to 1324 nm, which is equivalent to the conventional SMF, and the bending loss at the wavelength 1625 nm and the bending radius 7.5 mm is 1.0 dB / It is also possible to improve to 1 volume or less. Furthermore, the cut-off wavelength is 1530 nm or less, the bending loss is 1625 nm, which is equivalent to the conventional SMF, the bending radius is 30 mm, and the characteristic is 0.1 dB / 100 or less, and the MFD with a wavelength of 1310 nm is expanded to 14.1 μm. It becomes possible.

  1: Clad, 2: Core.

D. Boivin, et al., "All-Solid Single-Trench-Assisted Bend-Insensitive Fibers: Performances and Deployment Aspects", OFC2010, NThB3, (2010). Ikeda, et al. `` Low splice loss type low bending loss optical fiber '' IEICE Technical Report, OFT 2003-25, (2003). K. Mukasa, et al., "Comparisons of merits on wide-band transmission system between Using extremely improved SMFs with Aeff of 160μm2 and loss of 0.175dB / km and Using large-Aeff holey enabling transmission over 600nm bandwidth", OFC2008, OThR1 , (2008). ITU-T, Recommendation G.650.1 IEC60793-2-50 ITU-T, Recommendation G.652 M. Ohashi, et al., "Simple Approximations for Chromatic Dispersion in Single-Mode Fibers with Various Index Profiles", J. Lightwave Technol, LT-3, p.110 (1985).

Claims (9)

A clad having a uniform refractive index and a core having a refractive index higher than that of the clad and disposed in the center of the clad, where the refractive index of the core is n ₁ , and the refractive index of the clad is n ₂ , The relative refractive index difference Δ between the cladding and the core is

In an optical fiber having the relationship
The normalized frequency V of the core at a wavelength of 1550 nm is in the range of 2.00 to 3.35,
The outer diameter D of the clad Ri range near from 50 to 119μm,
A cut-off wavelength control type optical fiber , wherein the cut-off wavelength λ _c is shortened by 30 nm or more from the cut-off wavelength when the outer diameter D of the cladding is 125 μm . A clad having a uniform refractive index and a core having a refractive index higher than that of the clad and disposed in the center of the clad, where the refractive index of the core is n ₁ , and the refractive index of the clad is n ₂ , The relative refractive index difference Δ between the cladding and the core is

In an optical fiber having the relationship
The normalized frequency V of the core at a wavelength of 1550 nm is in the range of 2.00 to 3.35,
The outer diameter D of the cladding is in the range of 81 to 104 μm;
The radius a of the core is in the range of 4.20 to 5.15 μm;
Features and to Luke cutoff wavelength control optical fiber in that the relative refractive index difference Δ is in the range from 0.275 to 0.450%. A clad having a uniform refractive index and a core having a refractive index higher than that of the clad and disposed in the center of the clad, where the refractive index of the core is n ₁ , and the refractive index of the clad is n ₂ , The relative refractive index difference Δ between the cladding and the core is

In an optical fiber having the relationship
The normalized frequency V of the core at a wavelength of 1550 nm is in the range of 2.00 to 3.35,
The outer diameter D of the cladding is in the range of 68 to 100 μm;
The radius a of the core is in the range of 4.6 to 7.1 μm;
Features and to Luke cutoff wavelength control optical fiber in that the relative refractive index difference Δ is in the range from 0.230 to 0.575%. The relationship between the cutoff wavelength λ _{c at} the outer diameter D of the cladding and the normalized frequency V of the core is

The cutoff wavelength control type optical fiber according to any one of claims 1 to 3, wherein:   An optical fiber cable using the cut-off wavelength control type optical fiber according to any one of claims 1 to 4. A clad having a uniform refractive index and a core having a refractive index higher than that of the clad and disposed in the center of the clad, where the refractive index of the core is n ₁ , and the refractive index of the clad is n ₂ , The relative refractive index difference Δ between the cladding and the core is

Using an optical fiber having the relationship
Set the normalized frequency V of the core at a wavelength of 1550 nm to a range from 2.00 to 3.35,
Set the outer diameter D of the cladding in the range of 50 to 119 μm ,
A cut-off wavelength control method for an optical fiber , wherein the cut-off wavelength λ _c is shortened by 30 nm or more from the cut-off wavelength when the outer diameter D of the clad is 125 μm .   A clad having a uniform refractive index and a core having a higher refractive index than that of the clad and disposed in the center of the clad. ₁ , The refractive index of the cladding is n ₂ As a relative refractive index difference Δ between the cladding and the core,

Using an optical fiber having the relationship
  Set the normalized frequency V of the core at a wavelength of 1550 nm to a range from 2.00 to 3.35,
  The outer diameter D of the cladding is set in the range from 81 to 104 μm,
  Set the radius a of the core in the range from 4.20 to 5.15 μm,
  The relative refractive index difference Δ is set in a range from 0.275 to 0.450%.
  An optical fiber cut-off wavelength control method.   A clad having a uniform refractive index and a core having a higher refractive index than that of the clad and disposed in the center of the clad. ₁ , The refractive index of the cladding is n ₂ As a relative refractive index difference Δ between the cladding and the core,

Using an optical fiber having the relationship
  Set the normalized frequency V of the core at a wavelength of 1550 nm to a range from 2.00 to 3.35,
  Set the outer diameter D of the cladding in the range of 68 to 100 μm,
  The core radius a is set in the range of 4.6 to 7.1 μm,
  The relative refractive index difference Δ is set in a range from 0.230 to 0.575%.
  An optical fiber cut-off wavelength control method. The relationship between the cutoff wavelength λ _{c at} the outer diameter D of the cladding and the normalized frequency V of the core is

Cutoff wavelength controlling method of an optical fiber according to any one of claims 6 to 8, characterized in that meet.

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