JPS63306403A - Polarization maintaining fiber - Google Patents

Polarization maintaining fiber

Info

Publication number
JPS63306403A
JPS63306403A JP62142797A JP14279787A JPS63306403A JP S63306403 A JPS63306403 A JP S63306403A JP 62142797 A JP62142797 A JP 62142797A JP 14279787 A JP14279787 A JP 14279787A JP S63306403 A JPS63306403 A JP S63306403A
Authority
JP
Japan
Prior art keywords
refractive index
stress
core
base material
polarization
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
JP62142797A
Other languages
Japanese (ja)
Inventor
Yoshinori Hibino
善典 日比野
Fumiaki Hanawa
文明 塙
Masaharu Horiguchi
堀口　正治
Hiroyuki Suda
裕之 須田
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.)
Nippon Telegraph and Telephone Corp
Original Assignee
Nippon Telegraph and Telephone Corp
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 Nippon Telegraph and Telephone Corp filed Critical Nippon Telegraph and Telephone Corp
Priority to JP62142797A priority Critical patent/JPS63306403A/en
Publication of JPS63306403A publication Critical patent/JPS63306403A/en
Pending legal-status Critical Current

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
    • G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
    • G02B6/105—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type having optical polarisation effects
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/06—Doped silica-based glasses
    • C03B2201/08—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant
    • C03B2201/12—Doped silica-based glasses doped with boron or fluorine or other refractive index decreasing dopant doped with fluorine
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03B—MANUFACTURE, SHAPING, OR SUPPLEMENTARY PROCESSES
    • C03B2201/00—Type of glass produced
    • C03B2201/06—Doped silica-based glasses
    • C03B2201/30—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi
    • C03B2201/31—Doped silica-based glasses doped with metals, e.g. Ga, Sn, Sb, Pb or Bi doped with germanium
    • 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
    • C03B2203/222—Mismatching viscosities or softening points of glass layers

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Optics & Photonics (AREA)
  • Optical Fibers, Optical Fiber Cores, And Optical Fiber Bundles (AREA)
  • Glass Compositions (AREA)

Abstract

PURPOSE:To eliminate the refractive index matching of a clad and stress imparting part in the stage of a base material by means of this fiber by using SiO2 to a stress imparting part and imparting a double refractive index to a core by the residual stress depending on wire pulling tension. CONSTITUTION:The core 1a consists of a glass having a refractive index n1 and softening temp. T1 and the clad 2a consists of glass having the refractive index n2 smaller than the refractive index n1 of the core 1 and a softening temp. T2. The stress imparting part 3a disposed to apply an anisotropic stress to the core 1a consists of glass having a softening temp. T3. T3>T1 and T3>T1 are thus obtd. and the refractive index n3 of the stress imparting part 3a decreased by drawing has the relation n2>=n3. The clad 2a is formed of F-SiO2 and the stress imparting part 3a of SiO2. The refractive index of the stress imparting part 3a is matched at the time of drawing the base material. The matching of the refractive index is thereby not taken in the stage of the base material and the refractive index matching of the clad and the stress imparting part is taken in the drawing process.

Description

【発明の詳細な説明】 〔発明の産業上利用分野〕 本発明は偏波保持ファイバ、さらに詳細には、コヒーレ
ント通信や光応用計測などに用いられる偏波保持ファイ
バに関するものである。DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application of the Invention] The present invention relates to a polarization-maintaining fiber, and more particularly, to a polarization-maintaining fiber used in coherent communication, optical application measurement, and the like.

〔発明の従来技術〕[Prior art to the invention]

従来の偏波保持ファイバとして、コアに異方性応力を与
えてコアに複屈折率を持たせることにより、偏波面を保
持する方式の偏波保持ファイバが開発されている。As a conventional polarization-maintaining fiber, a polarization-maintaining fiber has been developed in which the plane of polarization is maintained by applying an anisotropic stress to the core so that the core has a birefringence index.

このうち、第１図に示すように、コアｌ、クラノド２、
および前記コア１の両側に対向して設けられた応力付与
部３からなるファイバで、コア１がＧｅＯ２ＳｉＯ２、
クラッド２がＦＧｅＯ２ＳｉＯ２で、応力付与部３がＳ
ｉＯ２であるファイバが提案されている（特願昭６０−
２２２８０２号）。Of these, as shown in Figure 1, core 1, cranoid 2,
and stress applying portions 3 provided oppositely on both sides of the core 1, the core 1 being GeO2SiO2,
The cladding 2 is FGeO2SiO2, and the stress applying part 3 is S
A fiber that is iO2 has been proposed (Japanese Patent Application 1986-
No. 222802).

この型のファイバでは、線引き過程において応力付与部
３が他の部分より最も軟化温度Ｔ３が高いため最初に硬
化し、それ以外の部分は低粘度であるため、線引きによ
りファイバに加わる線引き張力は応力付与部３のみで支
えられ、全体が硬化した後にも応力付与部３には、熱膨
張係数の差に起因した応力よりもはるかに大きな応力が
残留する。In this type of fiber, during the drawing process, the stress-applying part 3 hardens first because it has the highest softening temperature T3 than other parts, and the other parts have a low viscosity, so the drawing tension applied to the fiber during drawing causes stress. It is supported only by the stress applying part 3, and even after the entire stress applying part 3 is cured, a stress much larger than the stress caused by the difference in coefficient of thermal expansion remains in the stress applying part 3.

この残留応力によりコア１には２つの応力付与部３の配
置方向およびその直交方向で応力の値に差が生じること
により異方性応力が加わり、複屈折率が生しる。Due to this residual stress, an anisotropic stress is applied to the core 1 due to a difference in stress values in the arrangement direction of the two stress applying portions 3 and in a direction perpendicular thereto, resulting in birefringence.

一方、この屈折率分布は母材の段階で第２図に示すよう
になっている。この型のファイバでは応力付与部３の屈
折率ｎ３’　はＳｉＯ２のｎｏに等しいが、クラッドの
屈折率ｎ２より大きいとクラッドモードが発生し、シン
グルモードファイバとして好ましくない。従って、クラ
ッドにＳｉＯ２の屈折率を上げるドーパントとしてＧｅ
Ｏ２を、下げるドーパントとしてＦを添加し、ＦとＧｅ
Ｏ２の添加量を調節することによって、屈折率をＳｉＯ
２の屈折率ｎ。と等しくする必要があった。On the other hand, this refractive index distribution is as shown in FIG. 2 at the stage of the base material. In this type of fiber, the refractive index n3' of the stress applying portion 3 is equal to no of SiO2, but if it is larger than the refractive index n2 of the cladding, a cladding mode will occur, which is not preferable as a single mode fiber. Therefore, Ge is used as a dopant to increase the refractive index of SiO2 in the cladding.
F is added as a dopant to lower O2, and F and Ge
By adjusting the amount of O2 added, the refractive index can be adjusted to
The refractive index n of 2. It needed to be equal to.

〔発明が解決する問題点〕[Problems solved by the invention]

しかし、ファイバ母材作製法のうち、ＶＡＤ法において
ＦとＧｅＯ２の添加量を調節することは、ＧｅＯ２がＳ
ｉＯ２中に均一に分布しないので、非常に困難であると
いう欠点があった。また、内付けＣＶＤ法でも添加量変
化により、屈折率を調節することは困難であり、かつ第
１図に示す構造のファイバを、ＳｉＯ２の出発管を必要
とする内付けＣＶＤ法で作製した場合には応力付環部以
外にもその出発管部分が線引き張力を分担してしまうと
いう欠点があった。However, among the fiber base material manufacturing methods, adjusting the amount of F and GeO2 added in the VAD method is difficult because GeO2 is
It has the disadvantage that it is very difficult to distribute it uniformly in iO2. In addition, even with the internal CVD method, it is difficult to adjust the refractive index due to changes in the doping amount, and when a fiber with the structure shown in Figure 1 is manufactured using the internal CVD method, which requires a starting tube of SiO2. The disadvantage of this method is that, in addition to the stressed ring portion, the starting tube portion also shares the drawing tension.

本発明は上述の点に鑑みなされたものであり、線引き張
力によって軟化温度が高い応力付与部（ＳｉＯ２）に残
留する応力を利用してコアに複屈折率を誘起する偏波フ
ァイバにおいて、クラフト部と応力付与部の屈折率を２
種類のドーパントの添加量を変えることで調節していた
欠点を解決した偏波保持ファイバを提供することにある
。The present invention has been made in view of the above-mentioned points, and is a polarizing fiber that induces birefringence in the core by utilizing the stress remaining in the stress applying part (SiO2) whose softening temperature is high due to drawing tension. and the refractive index of the stress applying part is 2
It is an object of the present invention to provide a polarization-maintaining fiber that solves the drawbacks of adjustment by changing the amount of dopants added.

〔問題点を解決するための手段〕[Means for solving problems]

上記目的を達成するため、コアが屈折率ｎｌ、軟化温度
Ｔ□のガラスからなり、クラッドが前記コアの屈折率ｎ
ｌより小なる屈折率ｎ２、軟化温度Ｔ２のガラスからな
り、コアに異方性応力を与えるように配置された応力付
与部が、軟化温度Ｔ３のガラスからなる偏波保持ファイ
バであって、Ｔ３　＞’ｌ’工およびＴ３　＞’ｌ’２
で、かつ線引きにより低下した応力付与部の屈折率ｎ３
がｎ２≧ｎ３の関係となることを特徴としている。In order to achieve the above object, the core is made of glass with a refractive index nl and a softening temperature T□, and the cladding is made of glass with a refractive index nl of the core.
The polarization-maintaining fiber is made of glass having a refractive index n2 smaller than l and a softening temperature T2, and the stress applying section arranged to apply anisotropic stress to the core is made of glass having a softening temperature T3. ＞'l' engineering and T3 ＞'l'2
, and the refractive index n3 of the stress applying part decreased due to wire drawing.
is characterized by the relationship n2≧n3.

本発明は、コア、クラッド、応力付与部からなるファイ
バにおいて、クラフトをＦ−ＳｉＯ２、応力付与部を８
１０２とするとともに、前記母材を線引きする際、応力
付与部の屈折率をマツチングせしめることを最も主要な
特徴とする。従来の技術では、クラッドに屈折率マツチ
ングためＦ−Ｇ６０２　５ｔｏ２を用いており、作製上
困難な点が多かったが、本発明では母材段階では屈折率
のマツチングをとらず、線引き過程においてクラッドと
応力付与部の屈折率マツチングを取ることが最も異なる
。In the present invention, in a fiber consisting of a core, a cladding, and a stress applying part, the craft is F-SiO2 and the stress applying part is 8.
102, and the most important feature is that the refractive index of the stress applying portion is matched when drawing the base material. In the conventional technology, FG602 5to2 was used for refractive index matching of the cladding, which caused many difficulties in manufacturing, but in the present invention, refractive index matching is not performed at the base material stage, and the cladding and the cladding are matched during the drawing process. The biggest difference lies in the refractive index matching of the stress-applying part.

次ぎに、線引き過程においてクラッドと応力付与部の屈
折率マツチングを取る原理について説明する。第１図に
示す構成のファイバでは、応力付与部に線引き張力によ
りギガパスカル（ＧＰａ）オーダーの非常に大きな引張
り応力が残留する。Next, the principle of matching the refractive index between the cladding and the stress-applying part in the drawing process will be explained. In the fiber having the configuration shown in FIG. 1, a very large tensile stress on the order of gigapascals (GPa) remains in the stress applying portion due to the drawing tension.

ガラスのような等方向な物質に一方向から応力が働くと
光弾性効果と呼ばれる現象により屈折率が変化する。そ
の変化Δｎｒは、次式で近似される。When stress is applied to an isotropic material such as glass from one direction, the refractive index changes due to a phenomenon called the photoelastic effect. The change Δnr is approximated by the following equation.

Δｎｒ　　＃　Ｃ１σｚ　　　　　　　　（１）ここで
、σχは応力付与部に加えられた応力、Ｃ１は光弾性係
数である。ＳｉＯ２では、ｃｌの値は−４，２Ｘ　１０
−　”　Ｐ　ａ−’である。したがって、ＳｉＯ２にＧ
Ｐａオーダーの応力が加わると、屈折率は％を単位とし
て小数点１桁のオーダーで減少することがわかる。応力
付与部に加わるσ７は応力付与部の断面積に反比例し、
線引き張力に比例するのでクラッドの屈折率をＳｉＯ２
のそれより適当に小さくしておけば、線引き張力を変え
ることによって、応力付与部の屈折率をクラッドのそれ
に合わせることができる。例えば、ファイバ外径を１２
５μＩ１１．２つある応力付与部の半径を１５μｍとし
た場合、応力付与部（Ｓ　ｉ　０２　）の屈折率の減少
は第３図のようになる。本発明では、この現象を利用し
てコアに異方性応力を加えると同時にクラッドと応力付
与部の屈折率マツチングをとる。Δnr #C1σz (1) Here, σχ is the stress applied to the stress applying part, and C1 is the photoelastic coefficient. For SiO2, the value of cl is -4,2X 10
− ”P a−′. Therefore, G in SiO2
It can be seen that when a stress on the order of Pa is applied, the refractive index decreases on the order of one decimal point in %. σ7 applied to the stress applying part is inversely proportional to the cross-sectional area of the stress applying part,
Since it is proportional to the drawing tension, the refractive index of the cladding is SiO2
If the refractive index of the stress-applying part is made appropriately smaller than that of the cladding, the refractive index of the stress-applying part can be matched to that of the cladding by changing the drawing tension. For example, if the fiber outer diameter is 12
5 μI 11. When the radius of the two stress applying portions is 15 μm, the decrease in the refractive index of the stress applying portions (S i 02 ) is as shown in FIG. In the present invention, this phenomenon is utilized to apply anisotropic stress to the core and at the same time match the refractive index between the cladding and the stress applying portion.

この際の線引き張力は、好ましくは６０ｇ以上とするの
がよい。線引き張力が６０ｇ未満であると、残留応力が
十分コア部に複屈折率を有機せず、ファイバの偏波保持
性が悪くなる虞があるからである。The drawing tension at this time is preferably 60 g or more. This is because if the drawing tension is less than 60 g, the residual stress may not create sufficient birefringence in the core portion, and the polarization maintaining property of the fiber may deteriorate.

〔実施例１〕 第４図は本発明の偏波保持ファイバの実施例を示す断面
図である。コア１ａはＧｅＯ２−ＳｉＯ２よりなり、ク
ラッド２ａはＦ−ＳｉＯ２よりなり、応力付与部３ａは
ＳｉＯ２よりなっており、これらの軟化温度Ｔｘ　ｓ　
Ｔｔ　％　Ｔ３の関係はＴ３＞ＴＩおよびＴ３　＞Ｔｔ
となっている。[Example 1] FIG. 4 is a sectional view showing an example of the polarization maintaining fiber of the present invention. The core 1a is made of GeO2-SiO2, the cladding 2a is made of F-SiO2, and the stress applying part 3a is made of SiO2, and their softening temperature Tx s
Tt % T3 relationship is T3 > TI and T3 > Tt
It becomes.

この実施例においては、第４図より明らかなようにコア
１ａの廻りはクラッド２ａで囲まれているとともに、前
記コア１ａの両側に相互に対向し、かつ軸対称の位置に
、前記コア１ａの挿通方向に平行で、かつ離間して応力
付与部３ａが設けられた構造になっている。In this embodiment, as is clear from FIG. 4, the core 1a is surrounded by a cladding 2a, and the cladding 2a is placed on both sides of the core 1a, facing each other and axially symmetrical. It has a structure in which stress applying portions 3a are provided parallel to the insertion direction and spaced apart from each other.

線引きしてこの偏波保持ファイバを得る前の母材の径方
向の屈折率分布を第５図に示す。ｎｌ、ｎ２、ｎ３’　
は、それぞれ線引き後に、コア１ａ、クラッド２ａ、応
力付与部３ａとなる母材の屈折率であり、ＳｉＯ２の屈
折率をｎｏとするとｎ３’＝ｎＱである。ここでｎｌお
よびｎ２の値は、５ｉＯ１の屈折率ｎ０に対する比屈折
率差 −ｎＱ ｎｌ） で表して、それぞれΔｎ１＝０．４％およびΔｎ！−〇
、２％である。FIG. 5 shows the refractive index distribution in the radial direction of the base material before it is drawn to obtain this polarization maintaining fiber. nl, n2, n3'
are the refractive indexes of the base materials that will become the core 1a, cladding 2a, and stress-applying portion 3a after drawing, respectively, and assuming that the refractive index of SiO2 is no, n3'=nQ. Here, the values of nl and n2 are expressed as the relative refractive index difference of 5iO1 with respect to the refractive index n0 - nQ nl), and Δn1=0.4% and Δn!, respectively. -〇, 2%.

この母材を作製するには、ＶＡＤ法によりＧｅＯ２−ｓ
ｔｏｗのコア母材を作製し、次ぎにコア母材の外側に微
粒子の５ｉＯａｒ層をＶＡＤ外付は法により堆積させ、
ガラス化過程でＳｉＦ４を流してＦ−ＳｉＯ２クラッド
層母材とする。次ぎに、その母材のＦ−３ｉＯ１クラッ
ド部母材のコア母材の両側部分に超音波開口器を用いて
全体の母材外径比０．２５の穴を２個開けた。２個の穴
には５ｉｎｓ！ガラスロツドを挿入し、その後これを加
熱一体化した。To produce this base material, GeO2-s
A tow core base material is prepared, and then a 5iOar layer of fine particles is deposited on the outside of the core base material by a VAD external method.
During the vitrification process, SiF4 is poured to form an F-SiO2 cladding layer base material. Next, two holes with an overall base material outer diameter ratio of 0.25 were made in both sides of the core base material of the F-3iO1 cladding base material using an ultrasonic opening tool. 5ins in 2 holes! A glass rod was inserted and then heated and integrated.

得られたガラス母材を炉温度１９５０℃、線引き張力１
１０ｇで線引きして外径１２５μ−の偏波保持ファイバ
を得た。この線引き工程において、従来技術に述べたよ
うに応力付与部３ａの軟化温度Ｔ３が他の部分より最も
高いので応力付与部３ａが最初に軟化し、このため線引
き張力が応力付与部に加わることになり、さらに応力付
与部の熱膨張係数が他の部分と異なることによる応力も
加わる。従って、線引き後のファイバの屈折率分布は第
６図に示すようになった。図から、線引きされた応力付
与部の屈折率が式（１）の関係にしたがって母材のとき
のｎ３′　（＝ｎｔ＋）からクラッド部と同じ屈折率ｎ
３になっていることがわかる。The obtained glass base material was heated at a furnace temperature of 1950°C and a drawing tension of 1
A polarization maintaining fiber with an outer diameter of 125 μm was obtained by drawing at 10 g. In this wire drawing process, as described in the prior art, since the softening temperature T3 of the stress applying part 3a is higher than other parts, the stress applying part 3a softens first, and therefore, the wire drawing tension is applied to the stress applying part. Furthermore, stress is added due to the fact that the coefficient of thermal expansion of the stress-applying portion is different from that of other portions. Therefore, the refractive index distribution of the fiber after drawing was as shown in FIG. From the figure, it can be seen that the refractive index of the drawn stress-applying part changes from n3' (=nt+) of the base metal to n3' (=nt+), which is the same as the refractive index of the cladding part, according to the relationship of formula (1).
You can see that it is 3.

このファイバのカットオフ波長は１．２　μ潮であり、
波長１．３μ−の光源を用いて光学的磁界印加法により
ビート長りを測定したところ、Ｌ＝１．０鶴であった。The cutoff wavelength of this fiber is 1.2 μt;
When the beat length was measured by an optical magnetic field application method using a light source with a wavelength of 1.3 μ-, it was found that L=1.0.

このことから、本発明のファイバの複屈折率は１．２　
Ｘｌ０−３であることがわかった。From this, the birefringence index of the fiber of the present invention is 1.2.
It was found to be Xl0-3.

従来の軸対称応力付与型ファイバの最大複屈折率が１．
１　Ｘｌ０−３程度であることを考えると、本発明の偏
波保持ファイバは従来品以上の性能が容易に得られ、か
つ母材作製が簡単であるということがわかる。The maximum birefringence of conventional axisymmetric stress-applied fibers is 1.
Considering that it is about 1 Xl0-3, it can be seen that the polarization maintaining fiber of the present invention can easily obtain performance superior to that of conventional products, and the base material can be easily manufactured.

実施例１では、コアをＧ　ｅ　Ｏ２Ｓ　ｉ　Ｏ２とした
が、コアをＦ−ＧｅＯ２−３ｉ○２としても効果は同じ
であった。ここの実施例では第６図に示すように偏波保
持ファイバの応力付与部の屈折率ｎ３はクラッドの屈折
率ｎ２と等しい場合を示したが、ｎ３≦ｎｇの関係にあ
れば良い。In Example 1, the core was made of G e O2S i O2, but the same effect could be obtained even if the core was made of F-GeO2-3i○2. In this embodiment, as shown in FIG. 6, the refractive index n3 of the stress applying portion of the polarization maintaining fiber is equal to the refractive index n2 of the cladding, but it is sufficient if n3≦ng.

また、クラッドの比屈折率差Δｎ２を−０，１％以下、
あるいは応力付与部の断面積を小さくして、線引き張力
が６０ｇ以下でクラッドと応力付与部の屈折率マツチン
グをとった場合には残留応力が十分コア部に複屈折率を
誘起せず、ファイバの偏波保持特性が悪かった。In addition, the relative refractive index difference Δn2 of the cladding is -0.1% or less,
Alternatively, if the cross-sectional area of the stress-applying part is made small and the drawing tension is 60 g or less and the refractive index is matched between the cladding and the stress-applying part, the residual stress will not sufficiently induce birefringence in the core, and the fiber will Polarization maintenance characteristics were poor.

〔実施例２〕 第７図は本発明の第２の実施例を説明する図であって、
作製した偏波保持ファイバの断面図である。図中、１ａ
はＧｅＯ２Ｓｉｎ！コアであり、Ｆ−ＳｉＯ２クラツド
であり、３ａは５ｔｏｔの応力付与部である。また、実
施例１と同様に、これらの軟化温度Ｔ１、Ｔ１１．、Ｔ
３の関係はＴ３＞７’ｕおよびＴ３　＞’ｌ’２となっ
ている。[Embodiment 2] FIG. 7 is a diagram illustrating a second embodiment of the present invention,
FIG. 2 is a cross-sectional view of the produced polarization-maintaining fiber. In the figure, 1a
is GeO2Sin! The core is F--SiO2 cladding, and 3a is a 5 tot stress applying part. Further, as in Example 1, these softening temperatures T1, T11 . , T
3 is T3>7'u and T3>'l'2.

この実施例における偏波保持ファイバは、図より明らか
なように中心にコア１ａが軸方向に挿通しており、この
コア１ａを包囲するように応力付与部３ａが設けられて
いる。この応力付与部３ａの長手方向側面には断面半円
径のクラッド２ｂが相互に対向して設けられ、全体をク
ラッド２ａが覆うような構造になっている。As is clear from the figure, in the polarization maintaining fiber in this embodiment, a core 1a is inserted through the center in the axial direction, and a stress applying section 3a is provided so as to surround this core 1a. Clads 2b having a semicircular cross section are provided on the longitudinal side surfaces of this stress applying portion 3a to face each other, and the structure is such that the clads 2a cover the entire portion.

このようなコア母材のＳｉＯ２に対する比屈折率Δｎ１
は０．４％、クラッド母材（ファイバとなったときのク
ラッド２ａ、２ｂ）は比屈折率Δｎ２は一〇、２％であ
る。The relative refractive index Δn1 of such a core base material with respect to SiO2
is 0.4%, and the relative refractive index Δn2 of the cladding base material (cladding 2a, 2b when it becomes a fiber) is 10.2%.

第８図は、このような偏波保持ファイバを製造する前の
母材の入方向屈折率分布を示している。FIG. 8 shows the incoming refractive index distribution of the base material before manufacturing such a polarization maintaining fiber.

このような母材を作製するにあたっては、ＶＡＤ法にお
いてガラス化過程でＳｉＦ４を流してＦ−ｓｔｏｗのク
ラッド用母材を作製し、その母材に超音波開口器を用い
て内径が外径比０．７である円形の穴をあける。次ぎに
、ＧｅＯ２−ＳｉＯ２をコア母材、Ｓ　ｉ　ＯＩＩをク
ラッド母材とするシングルモードファイバ用母材をコア
母材を中心として両側あらこの母材の外径の０．２の厚
さになるようにスライスしくファイバのときの３８に相
当する）、クラッド母材（ファイバのときの２ａに相当
）に挿入した。残りの２つの半円径の空間に、半円径で
、前記クラフト母材と同じ屈折率を有するクラッド母材
（ファイバのときの２ｂに相当）のＦ−ＳｉＯ１！を前
記空間に合うように研磨し、挿入した。その後、これを
加熱一体化した。得られたガラス母材を炉温度１９５０
℃、線引き張力１１０ｇで線引きして外径１２５μｍの
偏波保持ファイバを得た。この線引き工程において、従
来技術に述べたように応力付与部３ａの軟化温度Ｔ３が
他の部分より最も高いので応力付与部３ａが最初に軟化
し、このため線引き張力が応力付与部に加わることにな
り、さらに応力付与部の熱膨張係数が他の部分と異なる
ことによる応力も加わる。従って、線引き後のファイバ
の屈折率分布は第９図に示すようになった。図から、線
引きされたファイバの応力付与部の屈折率が弐（１１の
関係に従って母材の時のｎ３°　（＝ｎｏ）から減少し
、クラッド部と同じ屈折率ｎ２になっていることがわか
る。To manufacture such a base material, SiF4 is poured during the vitrification process in the VAD method to create a base material for the F-stow cladding, and an ultrasonic opening tool is used on the base material to adjust the inner diameter to the outer diameter ratio. Drill a circular hole with a diameter of 0.7. Next, a single-mode fiber base material with GeO2-SiO2 as the core base material and SiOII as the clad base material is prepared so that the thickness on both sides of the core base material is 0.2 of the outer diameter of the base material. (corresponding to 38 in the case of fiber) and inserted into the cladding base material (corresponding to 2a in the case of fiber). In the remaining two semicircular spaces, a cladding base material (corresponding to 2b in the case of fiber) having a semicircular diameter and the same refractive index as the craft base material F-SiO1! was polished to fit the space and inserted. Thereafter, this was heated and integrated. The obtained glass base material was heated to a furnace temperature of 1950℃.
C. and a drawing tension of 110 g to obtain a polarization maintaining fiber with an outer diameter of 125 μm. In this wire drawing process, as described in the prior art, since the softening temperature T3 of the stress applying part 3a is higher than other parts, the stress applying part 3a softens first, and therefore, the wire drawing tension is applied to the stress applying part. Furthermore, stress is added due to the fact that the coefficient of thermal expansion of the stress-applying portion is different from that of other portions. Therefore, the refractive index distribution of the fiber after drawing was as shown in FIG. From the figure, it can be seen that the refractive index of the stressed part of the drawn fiber decreases from n3° (=no) in the base material according to the relationship 2 (11), and has become the same refractive index n2 as the cladding part. .

このファイバのカットオフ波長は１．２　μｍであり、
波長１．３μ曙の光源を用いて光学的磁界印加法により
ビート長りを測定したところ、Ｌ＝１．０鮪であった。The cutoff wavelength of this fiber is 1.2 μm,
When the beat length was measured by an optical magnetic field application method using a light source with a wavelength of 1.3 μm, L = 1.0 tuna.

このことから、本発明のファイバの複屈折率は１．２　
Ｘｌ０−３であることがわかった。From this, the birefringence index of the fiber of the present invention is 1.2.
It was found to be Xl0-3.

従来の軸対称応力付与型ファイバの最大複屈折率が１．
Ｉ　Ｘｌ０−３程度であることを考えると、本発明の偏
波保持ファイバは従来品以上の性能が容易に得られ、か
つ母材作製が簡単であるということがわかる。The maximum birefringence of conventional axisymmetric stress-applied fibers is 1.
Considering that it is about I Xl0-3, it can be seen that the polarization-maintaining fiber of the present invention can easily achieve better performance than conventional products, and can be easily manufactured as a base material.

実施例２では、コアをＧ　ｅ　Ｏ２Ｓ　ｉ　Ｏ２とした
が、コアをＦ−ＧｅＯ２−３　ｉ　０２としても効果は
同じであった。In Example 2, the core was made of G e O2S i O2, but the same effect was obtained even if the core was made of F-GeO2-3 i 02.

ここの実施例２では、実施例１と同様に第９図に示すよ
うに偏波保持ファイバの応力付与部の屈折率はクラッド
の屈折率ｎ２と等しい場合を示したが、応力付与部の屈
折率ｎ３≦ｎ２の関係にあれば良いのは、実施例１と同
様である。In Example 2 here, as in Example 1, the refractive index of the stress applying part of the polarization maintaining fiber is equal to the refractive index n2 of the cladding as shown in FIG. As in the first embodiment, it is sufficient that the ratio n3≦n2.

また、クラッドの比屈折率差Δｎ２を−０，１％以下、
あるいは応力付与部の断面積を小さくして、線引き張力
が６０ｇ以下でクラッドと応力付与部の屈折率マツチン
グをとった場合には残留応力が十分コア部に複屈折率を
誘起せず、ファイバの偏波保持特性が悪かった。In addition, the relative refractive index difference Δn2 of the cladding is -0.1% or less,
Alternatively, if the cross-sectional area of the stress-applying part is made small and the drawing tension is 60 g or less and the refractive index is matched between the cladding and the stress-applying part, the residual stress will not sufficiently induce birefringence in the core, and the fiber will Polarization maintenance characteristics were poor.

〔実施例３〕 第１０図は本発明の第３の実施例を説明する図であって
、作製したファイバの断面図である。１ｂはＧｅＯｔ−
３ｔｏｗのコアで、コア母材におけるＳｉｎｇに対する
比屈折率Δｎｌは０．４％、２ＣはＦ、５１０ｇのクラ
ッドで、クラッド母材における比屈折率Δｎ！１は−０
，２％、３ｄはＳｉｎｇの応力付与部である。[Example 3] FIG. 10 is a diagram illustrating a third example of the present invention, and is a cross-sectional view of a fabricated fiber. 1b is GeOt-
With a core of 3 tow, the relative refractive index Δnl for Sing in the core base material is 0.4%, 2C is F, and the relative refractive index Δnl in the cladding base material is 510g of cladding. 1 is -0
, 2%, and 3d are Sing stress applying parts.

この母材を作製するには、ＶＡＤ法においてガラス化過
程で５ｉＦａを流してＦ−ＳｉＯ２の母材を作製し、次
ぎに、その母材に超音波開口器を用いて楕円形の穴を開
けた。楕円形の穴には、ＧｅＯ２０−３ｉｎをコアとし
Ｓｉｎｇをクラッドとするファイバ用母材を楕円に研磨
したものを挿入し、その後これを加熱一体化した。To create this base material, in the VAD method, 5iFa is poured during the vitrification process to create a F-SiO2 base material, and then an oval hole is made in the base material using an ultrasonic opening tool. Ta. A fiber base material polished into an oval shape with a GeO20-3 inch core and a Sing cladding was inserted into the oval hole, and then heated and integrated.

得られたガラス母材を実施例１の場合と同一条件で線引
きした結果、同程度の複屈折率を有する偏波保持ファイ
バが得られた。As a result of drawing the obtained glass base material under the same conditions as in Example 1, a polarization maintaining fiber having a similar birefringence was obtained.

〔発明の効果〕〔Effect of the invention〕

以上説明したように、本発明の偏波保持ファイバでは応
力付与部にＳ　ｉ　ｏｔを用いて線引き張力に依存した
残留応力によりコアに複屈折率を与えている。その場合
、光弾性効果による応力付与部の屈折率減少を考慮して
、応力付与部の径および線引き張力を決定した。このた
め、従来のこの型の偏波保持ファイバでは非常に回能で
あった母材段階でのクラフトと応力付与部の屈折率マツ
チングの問題が、本発明のファイバでは取り除くことが
できるという利点がある。As explained above, in the polarization-maintaining fiber of the present invention, S iot is used in the stress-applying portion to impart birefringence to the core by residual stress depending on the drawing tension. In this case, the diameter of the stress applying part and the drawing tension were determined in consideration of the decrease in the refractive index of the stress applying part due to the photoelastic effect. Therefore, the fiber of the present invention has the advantage of being able to eliminate the problem of refractive index matching between the craft and the stress-applying part at the base material stage, which was extremely problematic in conventional polarization-maintaining fibers of this type. be.

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

第１図は従来の偏波保持ファイバの断面図、第２図は従
来の偏波保持ファイバ用母材の屈折率分布、第３図は線
引き張力と応力付与部の屈折率の減少の関係、第４図は
本発明（実施例１）の偏波保持ファイバの断面図、第５
図は本発明（実施例１）の偏波保持ファイバ用母材の屈
折率分布、第６図は本発明（実施例１）の偏波保持ファ
イバの屈折率分布、第７図は本発明（実施例２）の偏波
保持ファイバの断面図、第８図は　本発明（実施例２）
の偏波保持ファイバ用母材の屈折率分布、第９図は本発
明（実施例２）の偏波保持ファイバの屈折率分布、第１
０図は本発明（実施例３の偏波保持ファイバの断面図で
ある。 １．１ａ、１ｂ・・・コア、２．２ａ、２ｂ、２ｃ　・
・・クラッド、３．３ａ、３ｂ　　・・・応力付与部。 出願人代理人　　雨　宮　　　正　季 第１図 第２図 ０　　　　　　　　　　　　　　　５０　　　　　　　
　　　　　　　　ｔｏ。 線引き張１１（ｑ） 第４図 第５図 １１オイ杢 第６図 第１図Figure 1 is a cross-sectional view of a conventional polarization-maintaining fiber, Figure 2 is the refractive index distribution of a conventional polarization-maintaining fiber base material, and Figure 3 is the relationship between the drawing tension and the decrease in the refractive index of the stress-applying part. Figure 4 is a cross-sectional view of the polarization maintaining fiber of the present invention (Example 1);
The figure shows the refractive index distribution of the polarization maintaining fiber base material of the present invention (Example 1), Figure 6 shows the refractive index distribution of the polarization maintaining fiber of the present invention (Example 1), and Figure 7 shows the refractive index distribution of the polarization maintaining fiber of the present invention (Example 1). The cross-sectional view of the polarization maintaining fiber of Example 2), FIG. 8, shows the present invention (Example 2).
FIG. 9 shows the refractive index distribution of the polarization-maintaining fiber of the present invention (Example 2).
Figure 0 is a cross-sectional view of the polarization maintaining fiber of the present invention (Example 3). 1.1a, 1b...core, 2.2a, 2b, 2c.
...Clad, 3.3a, 3b...Stress applying part. Applicant's agent Masashi Amemiya Figure 1 Figure 2 0 50
to. Line tension 11 (q) Figure 4 Figure 5 Figure 11 Figure 6 Figure 1

Claims (4)

【特許請求の範囲】[Claims] （１）コアが屈折率ｎ＿１、軟化温度Ｔ＿１のガラスか
らなり、クラッドが前記コアの屈折率ｎ＿１より小なる
屈折率ｎ＿２、軟化温度Ｔ＿２のガラスからなり、コア
に異方性応力を与えるように配置された応力付与部が、
軟化温度Ｔ＿３のガラスからなる偏波保持ファイバであ
って、Ｔ＿３＞Ｔ＿１およびＴ＿３＞Ｔ＿２で、かつ線
引きにより低下した応力付与部の屈折率ｎ＿３がｎ＿２
≧ｎ＿３の関係となることを特徴とする偏波保持ファイ
バ。(1) The core is made of glass with a refractive index n_1 and a softening temperature T_1, and the cladding is made of glass with a refractive index n_2 and a softening temperature T_2 smaller than the refractive index n_1 of the core, so as to give anisotropic stress to the core. The placed stress applying part is
A polarization-maintaining fiber made of glass with a softening temperature T_3, where T_3>T_1 and T_3>T_2, and the refractive index n_3 of the stress-applying part reduced by drawing is n_2.
A polarization-maintaining fiber characterized by a relationship of ≧n_3. （２）前記応力付与部がＳｉＯ＿２（純石英ガラス）、
クラッド部がＦ−ＳｉＯ＿２であって、コア部がＧｅＯ
＿２−ＳｉＯ＿２またはＦ−ＧｅＯ＿２−ＳｉＯ＿２で
あることを特徴とする特許請求の範囲第１項に記載の偏
波保持ファイバ。(2) The stress applying part is SiO_2 (pure silica glass),
The cladding part is F-SiO_2 and the core part is GeO
_2-SiO_2 or F-GeO_2-SiO_2, the polarization maintaining fiber according to claim 1. （３）前記応力付与部は前記コアの挿通方向に平行に、
かつ離間して設けられていることを特徴とする特許請求
の範囲第１項および第２項に記載の偏波保持ファイバ。(3) The stress applying portion is parallel to the insertion direction of the core,
The polarization-maintaining fiber according to claim 1 or 2, wherein the polarization-maintaining fiber is provided spaced apart from each other. （４）前記応力付与部は前記コアを包囲して設けられて
いることを特徴とする特許請求の範囲第１項および第２
項に記載の偏波保持ファイバ。(4) Claims 1 and 2, characterized in that the stress applying section is provided to surround the core.
Polarization-maintaining fiber as described in section.
JP62142797A 1987-06-08 1987-06-08 Polarization maintaining fiber Pending JPS63306403A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP62142797A JPS63306403A (en) 1987-06-08 1987-06-08 Polarization maintaining fiber

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP62142797A JPS63306403A (en) 1987-06-08 1987-06-08 Polarization maintaining fiber

Publications (1)

Publication Number Publication Date
JPS63306403A true JPS63306403A (en) 1988-12-14

Family

ID=15323845

Family Applications (1)

Application Number Title Priority Date Filing Date
JP62142797A Pending JPS63306403A (en) 1987-06-08 1987-06-08 Polarization maintaining fiber

Country Status (1)

Country Link
JP (1) JPS63306403A (en)

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6283708A (en) * 1985-10-08 1987-04-17 Sumitomo Electric Ind Ltd Constant polarization optical fiber

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS6283708A (en) * 1985-10-08 1987-04-17 Sumitomo Electric Ind Ltd Constant polarization optical fiber

Similar Documents

Publication Publication Date Title
JP5409928B2 (en) Polarization-maintaining optical fiber
GB2221903A (en) Method of producing elliptic core type polarization-maintaining optical fibre
JP3833621B2 (en) Polarization maintaining optical fiber
JPH06235841A (en) Manufacture of 1xn achromatic coupler, fiber optic coupler and 1xn fiber optic coupler
GB2205828A (en) Methods of manufacturing polarisation-maintaining optical fibres
JP2002318315A (en) Optical fiber and method for manufacturing the same
JPS631252B2 (en)
JP4825092B2 (en) Polarization-maintaining optical fiber
GB2096788A (en) Single polarization single-mode optical fibers
JPS6365615B2 (en)
JPS63306403A (en) Polarization maintaining fiber
JPS59164505A (en) Single-polarization single-mode optical fiber
JPH01314209A (en) Constant polarization optical fiber
JPH0212887B2 (en)
JPS58135141A (en) Preparation of single polarized optical fiber
JPS58104035A (en) Preparation of optical fiber having single polarization diversity and single mode
JP2828251B2 (en) Optical fiber coupler
JPH01279211A (en) Polarized wave maintaining optical fiber
JPS6367168B2 (en)
JPH0210093B2 (en)
JPH0557215B2 (en)
JPS60246239A (en) Manufacture of polarization stabilized optical fiber
JP2003084160A (en) Polarization maintaining optical fiber
JPH0439605A (en) Elliptic core type polarization plane maintaining optical fiber and optical fiber polarizer
JPH04322207A (en) Optical fiber coupler and its manufacture