• 专利附录
  • 专利说明
  • 权利要求
  • 类似技术
  • 同族专利
  • 引用文献
  • 法律状态
  • 优先权
    • 专利摘要:
    The present invention relates to a low dispersion, low loss single mode optical fiber having a zero dispersion in the 1.55㎛ wavelength band, in particular the refractive index of the core by utilizing the characteristics of the MCVD (Modified Chemical Vapor Deposition) manufacturing method that is easy to control the refractive index of complex structures By manufacturing in multiple stages, the diameter of the core can be increased, and dispersion properties and other properties can be prevented from being greatly changed even in the small changes in the core diameter and refractive index. Therefore, the reproducibility is improved when the optical fiber is manufactured, and the stability of the geometry and the optical characteristics in the longitudinal direction of the base material can be ensured.
    公开号:KR19990038607A
    申请号:KR1019970058425
    申请日:1997-11-06
    公开日:1999-06-05
    发明作者:도문현；김진한；이지훈
    申请人:윤종용；삼성전자 주식회사；
    IPC主号:
    专利说明:

    Single mode fiber with multi-level core structure
    BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a single mode optical fiber having low dispersion and low loss in a wavelength range of 1.55 占 퐉, and more particularly, to an optical fiber having a multi-core core structure.
    With the recent rapid development of high speed and high capacity communication technology of optical transmission, the loss and dispersion characteristics of optical fiber has become a limiting factor for high speed and high capacity transmission. The limiting factor due to the optical fiber loss is the commercialization of the optical amplifier that can amplify the optical signal in the 1.55㎛ wavelength region, which uses the lowest loss value of 1.55㎛ wavelength in silica single mode optical fiber, and the loss characteristic is technical In terms of efficiency, it is no longer a limiting factor for high speed and large capacity transmission. Therefore, control of the dispersion characteristics of the optical fiber is a relatively major technical problem these days.
    However, the most widely used general single mode optical fiber is designed to have no dispersion value in 1.31㎛ wavelength region, so there is a limit to using 1.55㎛ wavelength due to high dispersion value despite low loss in 1.55㎛ wavelength region. .
    In general, the total dispersion of the single mode optical fiber is determined by the sum of the material dispersion and the waveguide dispersion. At this time, the material dispersion is determined by the intrinsic properties of the material constituting the optical fiber, the waveguide dispersion is determined by the structure of the optical fiber. Therefore, the relationship between the material dispersion and the waveguide dispersion according to the wavelength of the optical signal in the single mode optical fiber having zero dispersion in the wavelength region of about 1550 M will be described with reference to FIG. As shown in FIG. 1, the material dispersion Dm is generated by the fast propagation of an optical signal with a long wavelength and the slow propagation of an optical signal with a short wavelength due to the influence of a refractive index that varies with the wavelength of the optical signal. It has this positive value. In addition, the waveguide dispersion (Dw) acts inversely to the material dispersion and has a negative value. As a result, the total dispersion Dt is determined as shown in Fig. 1, and the region where the dispersion value of the total dispersion Dt becomes "0" is called zero dispersion. Therefore, by appropriately adjusting the material dispersion (Dm) and the waveguide dispersion (Dw), it is possible to lower the total dispersion (Dt) value in the wavelength region to be used. However, in order to control the dispersion by the material, the material used for the optical fiber must be changed. Therefore, in general, a method of varying the waveguide dispersion (Dw) is used to control the total dispersion value of the single mode optical fiber. In this case, the waveguide dispersion (Dw) may control the total dispersion value by adjusting the core diameter, core / clad, core refractive index distribution, and refractive index difference of the optical fiber. In other words, in order to manufacture a single mode optical fiber having a low dispersion value in a low loss 1.55 μm wavelength region, the refractive index of the optical fiber core and the diameter of the core should be increased more than the general single mode optical fiber for 1.31 μm wavelength.
    Therefore, a profile having a refractive index of the type shown in FIG. 2A disclosed in "low dispersion, low-loss single-mode optical waveguide" of US Pat. No. 4,715,679, and a "Single mode lightquide fiber having trapezoidal refractive index profile" of US Pat. No. 4,516,826. Profiles with a refractive index of the type as shown in FIG. 2B were prepared.
    Among them, US Patent No. 4,516,826 having a triangular or trapezoidal refractive index distribution as shown in FIG. 2B has a smaller core diameter 2a and mode field diameter 2W 0 than a general single mode optical fiber for 1.31 μm wavelength, The dispersion of the waveguide was controlled to lower the dispersion value in the 1.55 탆 wavelength region. However, such a structure must accurately control the geometry. This means that the splice loss (α s = 4.3 (a / W 0 ) 2 ) becomes large when the fiber and spherical field diameter are reduced, and the fiber diameter is too small to control waveguide dispersion. Microbending loss (hereinafter referred to as microbending loss) is rapidly increased. Thus, the U.S. Patent No. 4,516,826 allows the core to have a trapezoidal structure with a refractive index distribution to reduce the microbending loss of the optical fiber.
    However, the core has a triangular refractive index structure, and very precise process control is required to manufacture a fiber having a small core diameter. In particular, when the optical fiber having the triangular structure is manufactured by MCVD (Modified Chemical Vapor Deposition) method, a desired core diameter and core due to a center dip phenomenon in which the refractive index is decreased in the central part of the core generated in the present method In order to have a refractive index, more precise process control is required, which makes it difficult to secure reproducibility of the process.
    Accordingly, it is an object of the present invention to provide a single mode optical fiber having low dispersion and low loss in the 1.55 탆 wavelength band.
    Another object of the present invention is to provide a single-mode optical fiber having a multi-step structure of the core to facilitate the manufacturing and to ensure the reproduction of the process.
    The present invention for achieving the above object is a single mode optical fiber: a central core having a refractive index of n1 with a radius of a1 from a central axis, and a refractive index of the central core with a radius of a2 outside of the central core is smaller than the refractive index of n1 a first outer core portion having a refractive index of n 2 and surrounding the central core, and a first outer core having a refractive index of n 3 smaller than the refractive index n 2 of the first outer core at a radius of a3 outside the first outer core; A cladding portion surrounding the second outer core with a second outer core portion surrounding the second outer core and a refractive index of n0 smaller than the refractive index n2 of the second outer core with a radius of a4 on the outside of the second outer core; The refractive index of the clad portion and the refractive index of the first and second outer core portions do not have a value larger than that of the central core portion (n1> n2> n3> n0 and a1 <a2 <a3 <a4).
    1 is a view for explaining the relationship between material dispersion, waveguide dispersion, and total dispersion of a conventional 1550 M single mode optical fiber.
    2a and 2b is a view showing the structure of a dispersion moving optical fiber without dispersion in the conventional 1.55㎛ wavelength region.
    3 is a view showing a core structure of a single mode optical fiber having low dispersion and low loss in a wavelength range of 1.55 μm according to an embodiment of the present invention.
    Figures 4a and 4b is a view showing the difference in core diameter and core refractive index distribution according to the technical difference according to the prior art and the embodiment of the present invention when manufacturing a plurality of optical fiber base material.
    Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description of the present invention, if it is determined that a detailed description of a related known function or configuration may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.
    3 is a refractive index distribution diagram of a single mode optical fiber having a multi-step core structure according to an embodiment of the present invention. Referring to FIG. 3, first, in the configuration of the single mode optical fiber according to the present invention, the central core 2 has a refractive index of n1 at a radius of a1 from the central axis, and the radius of a2 is outside of the central core 2. The first outer core 4 having a refractive index of n2 smaller than the refractive index n1 of the central core 2 surrounds the central core 2, and the first outer core 4 has a radius of a3 outside the first outer core 4. A second outer core 6 having a refractive index of n3 smaller than the refractive index n2 of the first outer core 4 surrounds the first outer core 4, and finally, outside the second outer core 6. A cladding 8 having a refractive index of n0 less than the refractive index n2 of the second outer core 6 with a radius of a4 surrounds the second outer core 6.
    At this time, the first outer core 4 and the second outer core 6 can be distributed in all refractive index by the following equation (1).
    In Equation 1, r is the distance from the optical fiber center, a is the radius of the core, n 1 is the refractive index at the optical fiber center, and α is the refractive index profile parameter. Therefore, when α = 1, the refractive index profile is triangular type, and α = 2, the profile is hilly type, and α = ∞ when the profile is step type, the center core The refractive index profile of n (r) is changed by the above equation (1).
    In the optical fiber, the cladding is composed of pure silica (SiO 2 ), and the central core 2 and the first outer core 4 are composed of (SiO 2 -GeO 2 ) or (SiO 2 -GeO 2 -F). , The second outer core 6 is composed of (SiO 2 -GeO 2 -F). In this case, P 2 O 5 having a mole percentage or less may be added to the second outer core 6. In addition, the ratio of the refractive index difference (Δ1 = (n 1 -n 0 ) / n 1 ) between the center core 2 and the clad 8 is about 0.8%, and the ratio between the first outer core 4 and the clad 8 is about 0.8%. The refractive index difference (Δ2 = (n 2 -n 0 ) / n 2 ) is about 0.3%, and the difference in refractive index between the second side core 6 and the cladding 8 (Δ3 = (n 3 -n 0 ) / n 3 ) is about 0.1%. The diameter of the central core 2, the diameter of the first outer core 4, the diameter of the second outer core 6 and the clad 8 are 4.2 μm, 5.5 μm 16 μm, and 125 μm, respectively.
    As a result, the zero dispersion of the optical fiber obtained by the structure of the present invention described above is 1 ps / nm / km or less at a wavelength of 1.55 µm, the mode field diameter is 8.4 µm, the loss is 0.20 dB / km, and the zero dispersion slope is 0.09. ps / nm 2 / km.
    Therefore, the optical fiber manufactured according to the embodiment of the present invention described above may have the same effect as in FIGS. 4A and 4B. At this time, Figure 4a is a view showing the reproducibility of the base material having the same core diameter when manufacturing a plurality of base materials in the prior art and the present invention, Figure 4b is the same when manufacturing a plurality of base materials in the prior art and the present invention It is a figure which shows the reproducibility of the base material which has a core refractive index. 4A and 4B, the horizontal axis represents core diameter and core refractive index, and the vertical axis represents its occupation rate.
    Therefore, when taking the refractive index distribution of the base material according to an embodiment of the present invention in Figure 4a it is possible to manufacture more optical fiber base material having the same core diameter than the prior art. In addition, when taking the refractive index distribution of the base material according to an embodiment of the present invention in Figure 4b it is possible to manufacture more optical fiber base material having the same refractive index distribution than the prior art.
    Meanwhile, in the detailed description of the present invention, specific embodiments have been described, but various modifications may be made without departing from the scope of the present invention. Therefore, the scope of the present invention should not be limited to the described embodiments, but should be defined not only by the scope of the following claims, but also by those equivalent to the scope of the claims.
    As described above, in the present invention, the core diameter can be increased by multiplying the refractive index distribution of the core in the single mode optical fiber composed of the core and the clad, thereby facilitating the manufacture, and also increasing the diameter of the mode field to reduce the splice loss of the optical fiber. Lowered. In addition, the optical fiber structure is easy to manufacture, the dispersion value is lowered at a wavelength of 1.55㎛, to provide an optical fiber capable of ultra-high-speed long-distance communication.
    In addition, by bringing the structure of the optical fiber as described in the present invention, there is an advantage that it is possible to easily change all the optical properties of the optical fiber, including dispersion by changing the refractive index difference, the refractive index form and core diameter of each core.
    In addition, the optical fiber having the structure of the present invention has the advantage that the optical properties are not sensitive to the change in the refractive index and the core diameter due to the center dip in general, even if manufactured by the MCVD method in which the center dip exists in the center of the core.
    In addition, there is an advantage in that the difference in core diameter and refractive index in the longitudinal direction of the optical fiber is uniform so that the optical properties of the optical fiber are uniform.
    权利要求:
    Claims (7)
    [1" claim-type="Currently amended] In single-mode fiber:
    A central core having a refractive index of n1 at a radius of a1 from the central axis,
    A first outer core portion surrounding the central core with a refractive index of n2 smaller than the refractive index n1 of the central core at a radius of a2 outside the central core;
    A second outer core portion surrounding the first outer core with a refractive index of n3 smaller than the refractive index n2 of the first outer core at a radius of a3 outside the first outer core;
    A clad portion surrounding the second outer core with a refractive index of n0 smaller than the refractive index n2 of the second outer core at a radius of a4 outside the second outer core;
    Single mode optical fiber characterized in that the refractive index of the clad portion and the refractive index of the first and second outer core portion does not have a value larger than the refractive index of the central core portion (n1> n2> n3> n0, a1 <a2 <a3 <a4) .
    [2" claim-type="Currently amended] The method of claim 1,
    Single-mode optical fiber, characterized in that at least two neighboring cores having a higher refractive index than the cladding, the diameter is smaller than the center of the core core portion.
    [3" claim-type="Currently amended] The method of claim 1,
    The cladding portion is a silica component (SiO 2 ), the central core portion, the first outer core portion and the second outer core portion are all composed of (SiO 2 -GeO 2 ) composition, characterized in that.
    [4" claim-type="Currently amended] The method of claim 3,
    The first outer core portion and the second outer core portion is a single mode optical fiber, characterized in that made of a composition of SiO 2 -GeO 2 -F.
    [5" claim-type="Currently amended] The method of claim 3,
    The first outer core portion and the second outer core portion is a single mode optical fiber, characterized in that made of a composition of SiO 2 -GeO 2 -FP 2 O 5 .
    [6" claim-type="Currently amended] The method of claim 1,
    A single mode optical fiber having a zero-dispersion wavelength in the range of 1.50 micrometers to 1.60 micrometers, wherein the zero-dispersion slope is less than 0.09 ps / nm 2 / km.
    [7" claim-type="Currently amended] The method of claim 1,
    The refractive index distribution of the center core part, the first outer core part and the second outer core part areSingle mode optical fiber characterized in that all possible refractive index distribution.
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    同族专利:
    公开号 | 公开日
    CA2253579A1|1999-05-06|
    GB9824149D0|1998-12-30|
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    GB2331162B|2000-02-09|
    JPH11218633A|1999-08-10|
    CN1163771C|2004-08-25|
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    JP3040383B2|2000-05-15|
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    GB2331162A|1999-05-12|
    引用文献:
    公开号 | 申请日 | 公开日 | 申请人 | 专利标题
    法律状态:
    1997-11-06|Application filed by 윤종용, 삼성전자 주식회사
    1997-11-06|Priority to KR1019970058425A
    1999-06-05|Publication of KR19990038607A
    优先权:
    申请号 | 申请日 | 专利标题
    KR1019970058425A|KR19990038607A|1997-11-06|1997-11-06|Singlemode Fiber with Multilevel Core Structure|
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