JPS5831566B2 - low-order mode optical fiber - Google Patents
low-order mode optical fiberInfo
- Publication number
- JPS5831566B2 JPS5831566B2 JP55106527A JP10652780A JPS5831566B2 JP S5831566 B2 JPS5831566 B2 JP S5831566B2 JP 55106527 A JP55106527 A JP 55106527A JP 10652780 A JP10652780 A JP 10652780A JP S5831566 B2 JPS5831566 B2 JP S5831566B2
- Authority
- JP
- Japan
- Prior art keywords
- refractive index
- core
- optical fiber
- value
- cladding
- 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.)
- Expired
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/036—Optical fibres with cladding with or without a coating core or cladding comprising multiple layers
- G02B6/03616—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference
- G02B6/03622—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 2 layers only
- G02B6/03627—Optical fibres characterised both by the number of different refractive index layers around the central core segment, i.e. around the innermost high index core layer, and their relative refractive index difference having 2 layers only arranged - +
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/02—Optical fibres with cladding with or without a coating
- G02B6/028—Optical fibres with cladding with or without a coating with core or cladding having graded refractive index
- G02B6/0288—Multimode fibre, e.g. graded index core for compensating modal dispersion
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- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Chemical & Material Sciences (AREA)
- Dispersion Chemistry (AREA)
- Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)
- Waveguides (AREA)
Description
【発明の詳細な説明】
この発明は低次モードＬＰｏ１．ＬＰ１、を伝搬モード
とし、広帯域伝送路として使用可能な低次モード光ファ
イバに関するものである。DETAILED DESCRIPTION OF THE INVENTION This invention provides low-order mode LPo1. This invention relates to a low-order mode optical fiber that has LP1 as its propagation mode and can be used as a broadband transmission line.
従来この種の光ファイバは実質的にＬＰ。Conventionally, this type of optical fiber is essentially an LP.
１とＬＰ１１モードを伝搬モードとして耘り、このモー
ド間の群遅延時間差△τが等しいか、また著しく小さい
領域を使用している。1 and LP11 modes are used as propagation modes, and a region in which the group delay time difference Δτ between these modes is equal or extremely small is used.
その光ファイバの屈折率分布は第１図に示すような形状
をしていた。The refractive index distribution of the optical fiber had a shape as shown in FIG.
第１図に釦いて横軸は光ファイバの中心から半径方向に
於ける距離を、縦軸は屈折率をそれぞれ示す。In FIG. 1, the horizontal axis shows the distance in the radial direction from the center of the optical fiber, and the vertical axis shows the refractive index.
屈折率はコアの中心で最大値ｎ１であり中心から離れる
に従って小さくなりクラッド
ｎ（ｒ）−ｎ、 （１−２△ｐ （ｒ／ａ ） ）
Ａ （０≦ｒ≦ａ）の屈折率ｎ２は一定となっている
。The refractive index has a maximum value n1 at the center of the core, and decreases as it moves away from the center.
The refractive index n2 of A (0≦r≦a) is constant.
このコアの屈折率分布ｎ （ｒ）は次式で表わされる。The refractive index distribution n (r) of this core is expressed by the following equation.
ｒはコア中心から半径方向の距離、△は比屈折率で であった。r is the radial distance from the core center, △ is the relative refractive index Met.
一般に光ファイバの使用領域を表わすのに規格化周波数
Ｖ（Ｖ−２πａ ｎｌ ｉΣア］）（λは波長）が用い
られており、最適規格化周波数■。Generally, the normalized frequency V (V-2πa nl iΣa]) (λ is the wavelength) is used to express the usage area of an optical fiber, and the optimal normalized frequency .
Ｐｔは第３次モード群の遮断規格化周波数■。Pt is the cutoff normalized frequency of the third mode group.
２□により制限される。Limited by 2□.
従来の屈折率分布形では最適Ｖ値、即ち■。In the conventional refractive index distribution type, the optimum V value, that is, ■.
Ｐｔは４．６、最適αは４．５とし、又は■を４．３８
〜４．４６、αを５．０２〜５．５４としていた。Pt is 4.6, optimal α is 4.5, or ■ is 4.38
~4.46, and α was 5.02 to 5.54.
従来の最適Ｖ、最適αでの群遅延時間差△τを第４図に
曲線１に示す。Curve 1 in FIG. 4 shows the group delay time difference Δτ at the conventional optimum V and optimum α.
第４図で横軸は■、縦軸は１△τ１である。In FIG. 4, the horizontal axis is ■ and the vertical axis is 1Δτ1.
広帯域な伝送路としては△τの小さな領域がＶ値に対し
て広い程設計上有利となる。As a broadband transmission line, it is advantageous in terms of design that the region where Δτ is small is wider than the V value.
この評価として△τが２０ ｐｓｅｃ／Ｋｍ以下となる
Ｖ値の幅を、△τが最小となるＶ値で割った値Ｂｖを用
いると、従来の屈折率分布形では第４図に示した曲線１
の最適値でもＢｖ＝０．０１ときわめて狭く、わずかな
Ｖ値の変動に対しても大きな△τの変動となり、製造及
び設計において実際上かなり難しい問題があった。For this evaluation, if we use the value Bv, which is the width of the V value where △τ is 20 psec/Km or less, divided by the V value where △τ is the minimum, the curve shown in Figure 4 is obtained for the conventional refractive index distribution type. 1
Even the optimum value of Bv=0.01 is extremely narrow, and even a slight variation in V value results in a large variation in Δτ, which poses a practical problem in manufacturing and design.
なｚ−煽１□）１は第３次モード群の遮断波長である。1) 1 is the cutoff wavelength of the third-order mode group.
この発明の目的はＬＰｏｌ及びＬＰｌ、モード間の群遅
延時間差△τが規格化周波数■の変化に対して大きく変
動しない■の範囲があり、製造及び設計が容易な低次モ
ード光ファイバを提供することにある。An object of the present invention is to provide a low-order mode optical fiber that has a range of ■ in which the group delay time difference Δτ between LPol and LPl modes does not vary significantly with respect to changes in the normalized frequency ■, and is easy to manufacture and design. There is a particular thing.
この発明の他の目的はコアの外側の屈折率をクラッドの
屈折率よりも下げたり、またコアとクラッドの間に屈折
率の低い領域を設けることによってモード間の群遅延時
間差が小さいＶ値の領域を著しく拡大した低次モード光
ファイバを提供することにある。Another object of the present invention is to lower the refractive index of the outside of the core than the refractive index of the cladding, and to provide a region with a low refractive index between the core and the cladding, thereby reducing the V value so that the difference in group delay time between modes is small. The object of the present invention is to provide a low-order mode optical fiber with a significantly expanded area.
この発明によればρを１以上３以下にする。According to this invention, ρ is set to 1 or more and 3 or less.
第２図はこの発明の第１の実施例にも−ける径方向の屈
折率分布を示したものである。FIG. 2 shows the radial refractive index distribution in the first embodiment of the present invention.
縦軸は屈折率ｎ、横軸はコア中心からの距離ｒ、ｎｌは
コア中心０の屈折率、ｎ２はクラッドの屈折率、ａはコ
ア半径である。The vertical axis is the refractive index n, the horizontal axis is the distance r from the core center, nl is the refractive index at the core center 0, n2 is the refractive index of the cladding, and a is the core radius.
コア中心０からｒの位置における屈折率ｎ （ｒ）は、
△を比屈折率差、λを波長、α。The refractive index n (r) at the position r from the core center 0 is
△ is the relative refractive index difference, λ is the wavelength, and α.
ρを定数とする次の式で表わされる。It is expressed by the following equation where ρ is a constant.
つ１り屈折率はコア中心から離れるに従ってｎｌより漸
次減少し、ｎ２ より小さくなってクラッドの位置ａで
ｎ２に急に大きくなる。The refractive index gradually decreases from nl as it moves away from the core center, becomes smaller than n2, and suddenly increases to n2 at position a of the cladding.
この屈折率分布形（ρ〉１）を有し、ＬＰｏｌおよびＬ
Ｐ１１モードのみが伝搬可能な光ファイバの一例として
λ＝１．３μｍ、α−２，０３、ρ＝２．０としたもの
によって２モ一ド間の群遅延時間差△τとＶ値との関係
を第４図の曲線２に示す。Having this refractive index distribution shape (ρ〉1), LPol and L
As an example of an optical fiber in which only the P11 mode can propagate, the relationship between the group delay time difference △τ between two modes and the V value using λ = 1.3 μm, α - 2,03, and ρ = 2.0. is shown in curve 2 in FIG.
第４図中の焔１□）１は第３次モード群の遮断Ｖ値であ
る。Flame 1□)1 in FIG. 4 is the cutoff V value of the third mode group.
また△τが２０ ｐｓｅｃ／Ｋｍ以下となるＶ値の幅を
、△τが最小となるＶ値■。Also, the width of the V value where Δτ is 20 psec/Km or less is the V value ■ where Δτ is the minimum.
で割った値Ｂｖ（ｄＢｖ＝ ０．０８であり、曲線１に
示した従来の場合のＢｖ＝０．０１の８倍にもなってい
る。The value Bv (dBv = 0.08) divided by Bv = 0.08 is eight times as large as Bv = 0.01 in the conventional case shown in curve 1.
このようにρ〉１とすることで容易にＢｖを拡大するこ
とが可能である。By setting ρ>1 in this way, Bv can be easily expanded.
次に実際の広帯域伝送路としてこの発明を適用した場合
にα、ρおよび■がどのような値をとるかについて説明
する。Next, the values α, ρ, and ■ will be explained when this invention is applied to an actual broadband transmission line.
１ず一般に光通信には光源として半導体レーザが用いら
れてむり、これを用いた場合変調特性を考慮すると１．
６ Ｇ ｂｉｔ／ｓｅｅの伝送速度が限界と考えられる
。1. In general, a semiconductor laser is used as a light source for optical communication, and when considering the modulation characteristics when using this, 1.
A transmission speed of 6 Gbit/see is considered to be the limit.
広帯域光ファイバの適用は主に長距離伝送方式であり市
外局間の無中継伝送が目的とされる。Broadband optical fiber is mainly applied to long-distance transmission systems, and is intended for non-repeater transmission between long-distance offices.
市外局間距離が５０ｋｍＪｇ内となるのは、日本に督い
ては全体の９０優である。There are only 90 stations in Japan where the distance between local stations is within 50kmJg.
従って一つの基準として５０ｋｍの距離にち・いて１．
６ Ｇ ｂｉｔ／ｓｅｅの伝送を可能とするには現状の
技術レベルで８００ＭＨ２（３ｄＢ帯域幅）の帯域を必
要とする。Therefore, as a standard, 1.
To enable transmission of 6 Gbit/see, a band of 800 MH2 (3 dB bandwidth) is required at the current technological level.
これを△τに換算すると約・２０ ｐｓｅｃ／ｉ＜ｍと
なる。When this is converted into Δτ, it becomes approximately 20 psec/i<m.
従ってＩ△τ１≦２０（ｐｓｅｃ／ｋｍ）となる領域に
むいて光フアイバパラメータを定めればよい。Therefore, the optical fiber parameters may be determined in the region where IΔτ1≦20 (psec/km).
第５図にはＶ値と△τの関係を示し、横軸はＶ値、縦軸
は△τであり、ρ＝２．０の場合の種々のαについて示
し、点線の範囲は１△τ１≦２０ｐｓｅｃ／ｋｍとなる
■の範囲を示している。Figure 5 shows the relationship between V value and △τ, the horizontal axis is V value, the vertical axis is △τ, and the range of the dotted line is 1△τ1. The range of ■ is ≦20 psec/km.
ここで△τ１≦２０ ｐｓｅｃ／ ｋｍとなるＶ値の範
囲の△■をＶ。Here, △■ in the range of V values where △τ1≦20 psec/km is V.
で割った値Ｂｖ＝△ｖ／■ｏを用いて種種のρ釦よびα
を評価する。Using the value Bv=△v/■o divided by
Evaluate.
このＢｖとαとの関係を示したのが第６図である。FIG. 6 shows the relationship between Bv and α.
その横軸はαであり、縦軸はＢｖであってρ、■、Ｂｖ
の関係がわかりやすいようにρを適当に選んで示しであ
る。The horizontal axis is α, the vertical axis is Bv, and ρ, ■, Bv
ρ is chosen appropriately to make the relationship easier to understand.
ＢｖはＶ。Bv is V.
からのずれの許容度を表わして釦り光ファイバの製造性
と密接に関係する。It represents the tolerance for deviation from the button and is closely related to the manufacturability of the optical fiber.
そのためここではＢｖをＢｖ≧０，０５なるように〜の
下限を定める。Therefore, here, the lower limit of ~ is determined so that Bv≧0.05.
・これを第６図中に破線で示す。またクラッドの屈折率
よりも低い領域がコア内にある場合（１）＞ １ ）
ＬＰ２１ ｔ ＬＰＯ２モードが■。- This is shown by the broken line in Figure 6. Also, if there is a region in the core that has a lower refractive index than the cladding (1) > 1)
LP21 t LPO2 mode is ■.
２１付近においてもρ−１の場合と異なり、曲がりに対
する損失が小さくなりその影響が無視できなくなる。Also in the vicinity of 21, unlike the case of ρ-1, the loss due to bending becomes small and its influence cannot be ignored.
そのため動作Ｖ値はＬＰ１□モードの遮断■値■。Therefore, the operating V value is the cutoff ■ value ■ of LP1□ mode.
１、と、ＬＰ２１モードの遮断Ｖ値Ｖ。1, and the cutoff V value V in LP21 mode.
２１ との間になるように定める必要がある。21.
第５図の関係を多くのαについて求め、また第６図の関
係を多くのρについて求め、これらからＢｙ≧０．０５
となるαとρの範囲を示したのが第７図である。The relationship shown in Figure 5 is obtained for many α, and the relationship shown in Figure 6 is obtained for many ρ, and from these, By≧0.05
FIG. 7 shows the range of α and ρ.
第７図で横軸はα、縦軸はρであり、１△τ１≦２０
（ｐｓｅｃ／ｋｍ ） ｔ Ｂｖ≧０．０５となるα、
ρの範囲は第７図よりρ≧ｉ、ｓｏ、α≦２．０８２と
なることがわかる。In Figure 7, the horizontal axis is α, the vertical axis is ρ, and 1△τ1≦20
(psec/km) t α such that Bv≧0.05,
It can be seen from FIG. 7 that the range of ρ is ρ≧i, so, and α≦2.082.
一方ρの値は任意に大きくできるものではなく屈折率を
下げるドーパント（屈折率制御用注入材）としてフッ素
、ホウ素を用いた場合比較的実現できる値はクラッドの
５ｉ０２屈折率に対して比屈折率差で０．３〜０．６φ
である。On the other hand, the value of ρ cannot be arbitrarily increased, and when fluorine or boron is used as a dopant (implanted material for controlling the refractive index) to lower the refractive index, the value that can be achieved is a relative refractive index relative to the 5i02 refractive index of the cladding. The difference is 0.3 to 0.6φ
It is.
従って△を０．３％附近とするとρは３以下となり、第
７図の斜線領域が全ての条件を含む領域となる。Therefore, if Δ is set around 0.3%, ρ becomes 3 or less, and the shaded area in FIG. 7 is the area that includes all the conditions.
この図より第２図に示した実施例では１．９７≦α≦２
．０８２ 。From this figure, in the embodiment shown in FIG. 2, 1.97≦α≦2
．． 082.
１．８０≦ρ≦３．Ｖ ≦■≦■ｏ２．となる。1.80≦ρ≦3. V≦■≦■o2. becomes.
ｌｌ
第３図はこの発明第２の実施例にかける径方向の屈折率
分布を表わしたものである。FIG. 3 shows the radial refractive index distribution of the second embodiment of the present invention.
この例ではコアの中心０から離れるに従って屈折率はｎ
、より漸次減少し、ｎ２ より更に小さくなり、ｒ−ａ
で第１クラツドに達しその時の屈折率ｎ３に第１クラツ
ドは保持され、ｒ＝ｂの第２クラツドになると屈折率は
ｎ２に急に大きくなり第２クラツドの屈折率はｎ２ に
保持される。In this example, the refractive index increases as you move away from the core center 0.
, decreases more gradually and becomes even smaller than n2, r-a
When reaching the first cladding, the first cladding is maintained at the refractive index n3 at that time, and when reaching the second cladding, where r=b, the refractive index suddenly increases to n2 and the refractive index of the second cladding is maintained at n2.
コア中心からｒの位置における屈折率ｎ （ｒ）は次式
で表わされる。The refractive index n (r) at a position r from the center of the core is expressed by the following equation.
ｎ（ｒ）＝ ｎ １（］−２△ρ（ｒ／ａ）：］／２０
≦ｒ≦ａここでは一例としてｂ ／ ａ ＝ ０．８の
場合について説明する。n(r)=n 1(]-2Δρ(r/a):]/20
≦r≦a Here, the case where b/a = 0.8 will be explained as an example.
この場合も先に述べた第１の実施例と同様にｌ△τ１≦
２０ （ｐｓｅｃ／ｋｍ） Ｂ、≧０．０５となる領域
でパラメータの範囲を検討する。In this case, as in the first embodiment described above, l△τ1≦
20 (psec/km) B, consider the range of parameters in the region where ≧0.05.
第８図は第５図と対応しｂ ／ ａ ＝ ０．８に耘け
るＶ値と△τとの関係を示してむり、同時に種々の屈折
率分布形について１△τ１≦２０ （ｐｓｅｃ／ｋｍ）
となるＶの範囲を示す。Fig. 8 corresponds to Fig. 5 and shows the relationship between the V value and △τ that satisfies b/a = 0.8, and at the same time shows the relationship between 1△τ1≦20 (psec/km) for various refractive index distribution shapes. )
The range of V is shown below.
■値の範囲もＶｃｌ、＜ｉ＜３．２１としてＢｖＯ値を
種々のρ、αについて求めえものを第６図と対応して第
９図に示す。(2) The value range is Vcl, <i<3.21, and the BvO values obtained for various ρ and α are shown in FIG. 9 in correspondence with FIG. 6.
第１０図は第７図と同様にＢｖ≧０．０５の条件よりρ
とαの関係を求めたものである。Figure 10 shows ρ from the condition of Bv≧0.05, similar to Figure 7.
This is to find the relationship between and α.
さらに第１の実施例にち−けるρの条件ρ≦３を考慮す
るとｂ／ａ＝０．８でｌ△τ１≦２０ （ｐｓｅｃ／ｋ
ｍ）となるαとρの関係は第１０図の斜線で示した領域
となる。Furthermore, considering the condition of ρ≦3 in the first embodiment, b/a=0.8 and l△τ1≦20 (psec/k
The relationship between α and ρ resulting in m) corresponds to the shaded area in FIG.
第２の実施例に釦ける第１クラツドの効果はｂ ／ ａ
≦０．８のときに顕著に現われるため、■ｏ１１≦Ｖ≦
’Ｃ２１、ｂ ／ Ｂ≦０．８ 、１．４３≦ρ≦３が
条件となる。The effect of the first cladding in the second embodiment is b/a
It appears prominently when ≦0.8, so ■o11≦V≦
'C21, b/B≦0.8, 1.43≦ρ≦3 are the conditions.
以上説明したように従来の屈折率分布形では最適なファ
イバパラメータを設定してもＢｖ＝Ｏ，ＯＩであり、Ｂ
ｖをこれ以上拡大することは不呵能であった。As explained above, in the conventional refractive index distribution type, even if the optimal fiber parameters are set, Bv = O, OI, and B
It was impractical to expand v any further.
これに対しこの発明では第６図からもわかるようにρ＝
２．５．α−２，０１で従来のＢｖの２１倍となり、Ｂ
ｖ＝０．２１４で拡大できるという大きな利点を持つ。On the other hand, in this invention, as can be seen from Fig. 6, ρ=
2.5. α-2.01 is 21 times the conventional Bv, and B
It has the great advantage of being able to be expanded with v=0.214.
さらに第２の実施例では第９図よりρ−２，０゜α−２
，０１で従来の２，６倍のＢｖ値を、第１の実施例のρ
よりも小さい値で得ることができる。Furthermore, in the second embodiment, from FIG. 9, ρ-2,0°α-2
, 01, the Bv value is 2.6 times that of the conventional one, and the ρ of the first embodiment is
can be obtained with a smaller value.
これはｂ≦ｒ≦ａ ＶＣ＄”ける第１クラツドの効果に
よるものであり、第１０図の斜線部分が第１の実施例と
比較してかなり広くなっており、第１クラツドを有する
利点はきわめて太きい。This is due to the effect of the first cladding, where b≦r≦a VC$”, and the shaded area in FIG. 10 is considerably wider compared to the first embodiment, and the advantage of having the first cladding is Extremely thick.
また最適Ｖ値が大きい程光ファイバの接続損失が小さく
なる傾向にあり、この点について比較すると第１実施例
、第２実施例とも従来のＶ値の２倍以上大きくでき接続
に釦いても有利である。In addition, the larger the optimal V value, the smaller the optical fiber splice loss tends to be. Comparing this point, both the first and second embodiments can be more than twice as large as the conventional V value, which is advantageous even when splicing. It is.
従って広帯域でかつより低損失な伝送線路を設計する上
で著しい改善がこの発明によってなされることがわかる
。Therefore, it can be seen that the present invention provides a significant improvement in designing a transmission line with a wider band and lower loss.
第１図は従来の光ファイバの半径方向にむける屈折率分
布形を示す図、第２図はこの発明の第１の実施例の半径
方向における屈折率分布形の一例を示す図、第３図はこ
の発明の第２の実施例の半径方向に釦ける屈折率分布形
の一例を示す図、第４図は従来の光ファイバの最適値で
の群遅延時間差とＶ値との関係及びこの発明の第１の実
施例の群遅延時間差とＶ値との関係をそれぞれ示す図、
第５図はこの発明の第１実施例における種々のαに対す
るｖ値と△τとの関係を示す図、第６図はこの発明の第
１実施例にむける種々のρに対するαとＢｖとの関係を
示す図、第７図はこの発明の第１実施例のαとρとの関
係を示す図、第８図はこの発明の第２実施例に釦けるα
ｌＶ１△τの関係を示す図、第９図はこの発明の第２実
施例Ｖｃ釦けるρ＋ Ｂｙ ）αの関係を示す図、第
１０図はこの発明の第２実施例にち−けるｂ ／ ａ
＝ ０．８で１△τ≦２０ ｐｓｅｃ ／ｋｍの領域を
示すα、ρの関係図である。FIG. 1 is a diagram showing the refractive index distribution shape in the radial direction of a conventional optical fiber, FIG. 2 is a diagram showing an example of the refractive index distribution shape in the radial direction of the first embodiment of the present invention, and FIG. is a diagram showing an example of the refractive index profile buttoned in the radial direction according to the second embodiment of the present invention, and FIG. 4 is a diagram showing the relationship between the group delay time difference and the V value at the optimum value of a conventional optical fiber and the present invention Diagrams each showing the relationship between the group delay time difference and the V value of the first example,
FIG. 5 is a diagram showing the relationship between v values and Δτ for various α in the first embodiment of the invention, and FIG. 6 is a diagram showing the relationship between α and Bv for various ρ in the first embodiment of the invention. FIG. 7 is a diagram showing the relationship between α and ρ in the first embodiment of this invention, and FIG. 8 is a diagram showing the relationship between α and ρ in the second embodiment of this invention.
Figure 9 is a diagram showing the relationship between lV1△τ, Figure 9 is a diagram showing the relationship between Vc button (ρ+By)α, and Figure 10 is a diagram showing the relationship between ρ+By)α and b/ a
FIG. 2 is a relationship diagram of α and ρ showing a region where 1Δτ≦20 psec/km with = 0.8.
Claims (1)
低下しているコアと、そのコアの外側に一定の屈折率の
クラッドをもつ二層構造の光ファイバに３いて、上記コ
ア中心の屈折率ｎ、上記クラッドの屈折率ｎ２ 、比屈
折率差△、コア半径ａ、波長λ、定数α、ρとしてコア
中心からｒの位置にむける屈折率ｎ （ｒ）か に選定されていることを特徴とする低次モード光ファイ
バ。 ２ 中心から外側に向ってなだらかに屈折率が一様に低
下しているコアと、そのコアの外側に設けられ屈折率の
最も低い一定の幅の第１クラツドと、その外側に設けら
れた一定の屈折率をもつ第２クラツドとからなる三層構
造の光ファイバにむいて、コア中心の屈折率ｎｌ 、第
２クラツドの屈折率ｎ２ 、コア半径ａ、第１クラツド
の外半径ｂ、比屈折率差△、波長λ、定数α、ρとして
コア中心からｒの位置に釦ける屈折率ｎ （ｒ）がとす
るときＬＰ１□モードの遮断Ｖ値をＶ。 １１゜ＬＰ２□モードの遮断Ｖ値を■。 ２□ としての条件に選定されていることを特徴とする
低次モード光ファイバ。[Claims] 1. An optical fiber with a two-layer structure having a core whose refractive index gradually and uniformly decreases from the center outward, and a cladding with a constant refractive index on the outside of the core. Then, the refractive index n (r) from the core center to the position r from the core center is the refractive index n at the core center, the refractive index n2 of the cladding, the relative refractive index difference Δ, the core radius a, the wavelength λ, constants α and ρ. A low-order mode optical fiber characterized by being selected for. 2. A core whose refractive index gradually and uniformly decreases from the center to the outside, a first cladding with a constant width provided outside the core and having the lowest refractive index, and a constant width provided outside the core. For an optical fiber with a three-layer structure consisting of a second cladding with a refractive index of When the index difference △, the wavelength λ, the constants α, and ρ are the refractive index n (r) at a position r from the core center, the cutoff V value of the LP1□ mode is V. 11゜The cutoff V value of LP2□ mode is ■. 2. A low-order mode optical fiber characterized by being selected under the following conditions.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP55106527A JPS5831566B2 (en) | 1980-08-01 | 1980-08-01 | low-order mode optical fiber |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP55106527A JPS5831566B2 (en) | 1980-08-01 | 1980-08-01 | low-order mode optical fiber |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS5732404A JPS5732404A (en) | 1982-02-22 |
| JPS5831566B2 true JPS5831566B2 (en) | 1983-07-07 |
Family
ID=14435861
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP55106527A Expired JPS5831566B2 (en) | 1980-08-01 | 1980-08-01 | low-order mode optical fiber |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS5831566B2 (en) |
Families Citing this family (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPH0725736Y2 (en) * | 1987-07-22 | 1995-06-07 | 株式会社小田原機器 | Coin detection sensor |
| KR100403736B1 (en) | 2001-11-30 | 2003-10-30 | 삼성전자주식회사 | Wide band dispersion-controlled fiber |
| JP5193398B2 (en) * | 2011-02-09 | 2013-05-08 | 古河電気工業株式会社 | Optical fiber and optical transmission system |
| US9823413B2 (en) * | 2011-02-24 | 2017-11-21 | Ofs Fitel, Llc | Multicore fiber designs for spatial multiplexing |
| DE102011109838A1 (en) | 2011-05-27 | 2012-11-29 | J-Plasma Gmbh | optical fiber |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4966146A (en) * | 1972-09-11 | 1974-06-26 | ||
| JPS50131535A (en) * | 1974-04-03 | 1975-10-17 | ||
| JPS5250246A (en) * | 1975-10-20 | 1977-04-22 | Hitachi Ltd | Light transmitting line |
| JPS543553A (en) * | 1977-06-10 | 1979-01-11 | Nippon Telegr & Teleph Corp <Ntt> | Optical line |
| JPS5443749A (en) * | 1977-09-13 | 1979-04-06 | Nippon Telegr & Teleph Corp <Ntt> | Wide range oprical fiber |
-
1980
- 1980-08-01 JP JP55106527A patent/JPS5831566B2/en not_active Expired
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS4966146A (en) * | 1972-09-11 | 1974-06-26 | ||
| JPS50131535A (en) * | 1974-04-03 | 1975-10-17 | ||
| JPS5250246A (en) * | 1975-10-20 | 1977-04-22 | Hitachi Ltd | Light transmitting line |
| JPS543553A (en) * | 1977-06-10 | 1979-01-11 | Nippon Telegr & Teleph Corp <Ntt> | Optical line |
| JPS5443749A (en) * | 1977-09-13 | 1979-04-06 | Nippon Telegr & Teleph Corp <Ntt> | Wide range oprical fiber |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS5732404A (en) | 1982-02-22 |
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