JPH08136756A - Single mode optical fiber - Google Patents

Single mode optical fiber

Info

Publication number
JPH08136756A
JPH08136756A JP7232567A JP23256795A JPH08136756A JP H08136756 A JPH08136756 A JP H08136756A JP 7232567 A JP7232567 A JP 7232567A JP 23256795 A JP23256795 A JP 23256795A JP H08136756 A JPH08136756 A JP H08136756A
Authority
JP
Japan
Prior art keywords
refractive index
optical fiber
recess
single mode
mode optical
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
JP7232567A
Other languages
Japanese (ja)
Inventor
Taeko Shibuta
妙子 渋田
Tadashi Takahashi
正 高橋
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Furukawa Electric Co Ltd
Original Assignee
Furukawa Electric Co Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Furukawa Electric Co Ltd filed Critical Furukawa Electric Co Ltd
Priority to JP7232567A priority Critical patent/JPH08136756A/en
Publication of JPH08136756A publication Critical patent/JPH08136756A/en
Pending legal-status Critical Current

Links

Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B37/00—Manufacture or treatment of flakes, fibres, or filaments from softened glass, minerals, or slags
    • C03B37/01—Manufacture of glass fibres or filaments
    • C03B37/012—Manufacture of preforms for drawing fibres or filaments
    • C03B37/014—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD]
    • C03B37/018—Manufacture of preforms for drawing fibres or filaments made entirely or partially by chemical means, e.g. vapour phase deposition of bulk porous glass either by outside vapour deposition [OVD], or by outside vapour phase oxidation [OVPO] or by vapour axial deposition [VAD] by glass deposition on a glass substrate, e.g. by inside-, modified-, plasma-, or plasma modified- chemical vapour deposition [ICVD, MCVD, PCVD, PMCVD], i.e. by thin layer coating on the inside or outside of a glass tube or on a glass rod
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2203/00—Fibre product details, e.g. structure, shape
    • C03B2203/10—Internal structure or shape details
    • C03B2203/22—Radial profile of refractive index, composition or softening point
    • C03B2203/24—Single mode [SM or monomode]
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2203/00—Fibre product details, e.g. structure, shape
    • C03B2203/36—Dispersion modified fibres, e.g. wavelength or polarisation shifted, flattened or compensating fibres (DSF, DFF, DCF)

Abstract

PURPOSE: To obtain a single mode optical fiber which is good in both of dispersion characteristics and bending loss characteristic by providing the refractive index profile of a core part with a gentle recess and specifying the difference in the specific refractive index of the recess to a specific value or below. CONSTITUTION: The refractive index profile of the core part 1 of the single mode optical fiber of a 1.3μm band having the refractive index profile of a step type in which the refractive index n1 of the core part 1 is higher than the refractive index n2 of the clad part 2 has the gentle recess and the recess is <=2.0% in the difference in the specific refractive index. Such difference is based on a theoretical simulation and if the difference in the specific refractive index of such recess is confined to <=0.2%, the single mode optical fiber good in both of the dispersion characteristic and the bending loss characteristic is obtd. The reason why the difference in the specific refractive index of the recess is confined to <=0.2% lies in that the dispersion at the same Q value (the same bending loss) is not improved as compared with the conventional case where there is no recess if the size of the recess increases 0.2%.

Description

【発明の詳細な説明】Detailed Description of the Invention

【０００１】[0001]

【産業上の利用分野】本発明は、シングルモード光ファ
イバの屈折率プロファイルに関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a refractive index profile of a single mode optical fiber.

【０００２】[0002]

【従来の技術】従来、シングルモード光ファイバはコア
部分と該コア部分の周囲を取り囲むクラッド部分からな
り、その基本的な屈折率プロファイルは、図５に示すよ
うに、光ファイバ軸に垂直な断面内で、屈折率がクラッ
ド部分２の値ｎ2 からコア部分１の値ｎ1 に階段状に変
化しているステップ型である。ところで、シングルモー
ド光ファイバの伝送特性は分散と損失によって表され
る。この分散特性は比屈折率差Δ＝（ｎ1 −ｎ2 ）／ｎ
1 の小さい方が良好であり、曲げ損失特性はΔの大きい
方が良好であることが知られている。2. Description of the Related Art Conventionally, a single mode optical fiber has a core portion and a cladding portion surrounding the core portion, and its basic refractive index profile has a cross section perpendicular to the optical fiber axis as shown in FIG. in inner, a step type refractive index is changed stepwise from the value n 2 of the cladding portion 2 to the value n 1 of the core portion 1. By the way, the transmission characteristics of a single mode optical fiber are represented by dispersion and loss. This dispersion characteristic has a relative refractive index difference Δ = (n 1 −n 2 ) / n
It is known that a smaller value of 1 is better, and a larger bending loss characteristic is better.

【０００３】[0003]

【発明が解決しようとする課題】上述のように、従来の
シングルモード光ファイバには、分散特性を良くしよう
としてΔを小さくすると、曲げ損失特性が悪化するとい
う問題があった。As described above, the conventional single mode optical fiber has a problem that the bending loss characteristic is deteriorated when Δ is reduced in order to improve the dispersion characteristic.

【０００４】[0004]

【課題を解決するための手段】本発明は上記問題点を解
決したシングルモード光ファイバを提供するもので、コ
ア部分と該コア部分の周囲を取り囲むクラッド部分から
なり、コア部分の屈折率がクラッド部分の屈折率よりも
大きく、ステップ型の屈折率プロファイルを有する１．
３μｍ帯シングルモード光ファイバにおいて、コア部分
の屈折率プロファイルは少なくとも一個のなめらかな凹
みを有し、該凹みは、比屈折率差が０．２％以下である
ことを特徴とするものである。SUMMARY OF THE INVENTION The present invention provides a single mode optical fiber which solves the above problems and comprises a core portion and a clad portion surrounding the core portion, and the refractive index of the core portion is the clad. 1. Has a step type refractive index profile that is larger than the refractive index of the part
In the 3 μm band single mode optical fiber, the refractive index profile of the core portion has at least one smooth dent, and the dent has a relative refractive index difference of 0.2% or less.

【０００５】[0005]

【作用】本発明は理論的なシュミレーションに基づいた
ものである。即ち、コア部分の屈折率プロファイルに少
なくとも一個の凹みを設け、該凹みの比屈折率差を０．
２％以下にすると、分散特性および曲げ損失特性がとも
に良好なシングルモード光ファイバが得られる。ここ
で、凹みの比屈折率差を０．２％以下にする理由は、凹
みの大きさが０．２％を越えると、同一Ｑ値（同一曲げ
損失）での分散が従来の凹みがない場合に比較して改善
されないからである。The present invention is based on theoretical simulation. That is, at least one recess is provided in the refractive index profile of the core portion, and the relative refractive index difference of the recess is 0.
When it is 2% or less, a single mode optical fiber having excellent dispersion characteristics and bending loss characteristics can be obtained. Here, the reason why the relative refractive index difference of the dents is 0.2% or less is that when the size of the dents exceeds 0.2%, the dispersion with the same Q value (the same bending loss) does not have the conventional dents. This is because there is no improvement compared to the case.

【０００６】[0006]

【実施例】以下、図面に示した実施例に基づいて本発明
を詳細に説明する。図１（ａ）は本発明に係るシングル
モード光ファイバの一実施例の屈折率プロファイルを示
す図であり、コア部分に比屈折率差の凹みを設けてあ
る。図１（ｂ）、（ｃ）は比較例となる光ファイバの屈
折率プロファイルを示す図であり、コア部分がフラット
なもの、および凸形状であるものを示している。図１
（ａ）〜（ｃ）に示す３例の屈折率プロファイルをもつ
光ファイバについて、Ｑ値（ＭＦＤ／λC ）と波長１．
２８５μｍでの分散との関係を測定した。その結果を図
２に示す。ここで、Ｑ値は曲げ損失特性のパラメータで
あり、値が大きくなると、曲げ損失特性が悪いことを示
すことが知られている。なお、ＭＦＤは光パワーがどの
程度拡がっているかを示すモードフィールド径、λC は
高次モードを遮断するカットオフ波長である。DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the embodiments shown in the drawings. FIG. 1 (a) is a diagram showing a refractive index profile of an embodiment of a single mode optical fiber according to the present invention, in which a core portion is provided with a recess for relative refractive index difference. 1B and 1C are views showing the refractive index profile of an optical fiber as a comparative example, in which the core portion is flat and the core portion is convex. FIG.
Regarding the optical fibers having the refractive index profiles of the three examples shown in (a) to (c), the Q value (MFD / λ C ) and the wavelength 1.
The relationship with the dispersion at 285 μm was measured. The result is shown in FIG. Here, the Q value is a parameter of the bending loss characteristic, and it is known that the larger the value, the worse the bending loss characteristic. It should be noted that MFD is a mode field diameter indicating how much the optical power is expanded, and λ C is a cutoff wavelength that cuts off higher-order modes.

【０００７】図２は、図１（ａ）〜（ｃ）に示す３例の
屈折率プロファイルをもつ光ファイバについて、Ｑ値と
１．２８５μｍでの分散の関係を示すものである。図２
からわかるように、Ｑ値が等しい場合、図１（ａ）に示
す屈折率プロファイルのようにコア部分に凹みがある光
ファイバが最も小さい分散を示している。即ち、コア部
分に凹みを有する屈折率プロファイルの光ファイバが、
フラット状の光ファイバよりも曲げ損失特性を悪化させ
ることなく、分散特性を向上させることができる。図１
（ａ）に示す屈折率プロファイルにおいて、Ｑ値を７．
４に一定にして、凹みの比屈折率差と分散の関係を測定
した結果を図３に示す。ここで、Ｑ値を７．４にした理
由は、１．３μｍ帯シングルモード光ファイバの特性値
が一般的にＭＦＤ＝９．２５μｍ、λC ＝１．２５μｍ
となるからである。図３からわかるように、凹みの比屈
折率差Δが０．２％以下では、フラット型の屈折率プロ
ファイル（Δ＝０）を有する光ファイバよりも分散特性
が向上する。図１（ａ）に示す屈折率プロファイルを有
する光ファイバは、ＶＡＤ法により製作することができ
る。なお、本発明にかかる屈折率プロファイルとして
は、図１（ａ）に示す形状のものに限定されず、図４
（ａ）、（ｂ）に示すようにさまざまな形状を用いるこ
とができる。FIG. 2 shows the relationship between the Q value and dispersion at 1.285 μm for the optical fibers having the refractive index profiles of the three examples shown in FIGS. 1 (a) to 1 (c). Figure 2
As can be seen from the above, when the Q values are the same, the optical fiber having a recess in the core portion as shown in the refractive index profile shown in FIG. 1A exhibits the smallest dispersion. That is, an optical fiber with a refractive index profile having a recess in the core portion,
The dispersion characteristic can be improved without deteriorating the bending loss characteristic as compared with the flat optical fiber. FIG.
In the refractive index profile shown in (a), the Q value is 7.
FIG. 3 shows the result of measuring the relationship between the relative refractive index difference of the dent and the dispersion while keeping it constant at 4. Here, the reason for setting the Q value to 7.4 is that the characteristic values of the 1.3 μm band single mode optical fiber are generally MFD = 9.25 μm and λ C = 1.25 μm.
This is because As can be seen from FIG. 3, when the relative refractive index difference Δ of the recess is 0.2% or less, the dispersion characteristics are improved as compared with the optical fiber having the flat type refractive index profile (Δ = 0). The optical fiber having the refractive index profile shown in FIG. 1A can be manufactured by the VAD method. The refractive index profile according to the present invention is not limited to the shape shown in FIG.
Various shapes can be used as shown in (a) and (b).

【０００８】[0008]

【発明の効果】以上説明したように本発明によれば、コ
ア部分と該コア部分の周囲を取り囲むクラッド部分から
なり、コア部分の屈折率がクラッド部分の屈折率よりも
大きく、ステップ型の屈折率プロファイルを有する１．
３μｍ帯シングルモード光ファイバにおいて、コア部分
の屈折率プロファイルは少なくとも一個のなめらかな凹
みを有し、該凹みは、比屈折率差が０．２％以下である
ため、分散特性および曲げ損失特性がともに良好なシン
グルモード光ファイバが得られるという優れた効果があ
る。As described above, according to the present invention, the core portion and the cladding portion surrounding the core portion are provided, and the refractive index of the core portion is larger than the refractive index of the cladding portion. With rate profile 1.
In a 3 μm band single mode optical fiber, the refractive index profile of the core portion has at least one smooth dent, and the dent has a relative refractive index difference of 0.2% or less. Both have an excellent effect that a good single mode optical fiber can be obtained.

【図面の簡単な説明】[Brief description of drawings]

【図１】（ａ）は本発明に係るシングルモード光ファイ
バの一実施例の屈折率プロファイルを示す図、（ｂ）、
（ｃ）は比較例となる光ファイバの屈折率プロファイル
を示す図である。FIG. 1A is a diagram showing a refractive index profile of an embodiment of a single mode optical fiber according to the present invention, FIG.
(C) is a figure which shows the refractive index profile of the optical fiber used as a comparative example.

【図２】上記光ファイバについて、Ｑ値と分散の関係を
示す図である。FIG. 2 is a diagram showing a relationship between a Q value and dispersion of the optical fiber.

【図３】上記実施例において、凹みの比屈折率差と分散
の関係を示す図である。FIG. 3 is a diagram showing a relationship between a relative refractive index difference of a recess and dispersion in the above-mentioned embodiment.

【図４】（ａ）、（ｂ）は他の実施例の屈折率プロファ
イルを示す図である。FIG. 4A and FIG. 4B are views showing refractive index profiles of other examples.

【図５】シングルモード光ファイバの屈折率プロファイ
ルの説明図である。FIG. 5 is an explanatory diagram of a refractive index profile of a single mode optical fiber.

【符号の説明】[Explanation of symbols]

１ コア部分 ２ クラッド部分 1 core part 2 clad part

Claims (1)

【特許請求の範囲】[Claims] 【請求項１】 コア部分と該コア部分の周囲を取り囲む
クラッド部分からなり、コア部分の屈折率がクラッド部
分の屈折率よりも大きく、ステップ型の屈折率プロファ
イルを有する１．３μｍ帯シングルモード光ファイバに
おいて、コア部分の屈折率プロファイルは少なくとも一
個のなめらかな凹みを有し、該凹みは、比屈折率差が
０．２％以下であることを特徴とするシングルモード光
ファイバ。1. A 1.3 μm band single mode light having a core portion and a cladding portion surrounding the core portion, wherein the refractive index of the core portion is larger than that of the cladding portion and has a step type refractive index profile. In the fiber, the refractive index profile of the core portion has at least one smooth depression, and the depression has a relative refractive index difference of 0.2% or less.
JP7232567A 1994-09-16 1995-09-11 Single mode optical fiber Pending JPH08136756A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP7232567A JPH08136756A (en) 1994-09-16 1995-09-11 Single mode optical fiber

Applications Claiming Priority (3)

Application Number Priority Date Filing Date Title
JP6-221738 1994-09-16
JP22173894 1994-09-16
JP7232567A JPH08136756A (en) 1994-09-16 1995-09-11 Single mode optical fiber

Publications (1)

Publication Number Publication Date
JPH08136756A true JPH08136756A (en) 1996-05-31

Family

ID=26524463

Family Applications (1)

Application Number Title Priority Date Filing Date
JP7232567A Pending JPH08136756A (en) 1994-09-16 1995-09-11 Single mode optical fiber

Country Status (1)

Country Link
JP (1) JPH08136756A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103869410A (en) * 2014-01-26 2014-06-18 烽火通信科技股份有限公司 Small bending radius single-mode optical fiber with compatibility

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN103869410A (en) * 2014-01-26 2014-06-18 烽火通信科技股份有限公司 Small bending radius single-mode optical fiber with compatibility

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