JPH02181708A - Two core type temperature detecting optical fiber - Google Patents
Two core type temperature detecting optical fiberInfo
- Publication number
- JPH02181708A JPH02181708A JP1001492A JP149289A JPH02181708A JP H02181708 A JPH02181708 A JP H02181708A JP 1001492 A JP1001492 A JP 1001492A JP 149289 A JP149289 A JP 149289A JP H02181708 A JPH02181708 A JP H02181708A
- Authority
- JP
- Japan
- Prior art keywords
- core
- optical fiber
- light
- cores
- axis
- 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
Links
- 239000013307 optical fiber Substances 0.000 title claims abstract description 45
- 230000008878 coupling Effects 0.000 claims abstract description 11
- 238000010168 coupling process Methods 0.000 claims abstract description 11
- 238000005859 coupling reaction Methods 0.000 claims abstract description 11
- 238000005253 cladding Methods 0.000 claims description 16
- 230000003287 optical effect Effects 0.000 claims description 4
- 230000010287 polarization Effects 0.000 abstract description 6
- 238000001514 detection method Methods 0.000 abstract description 5
- 239000000835 fiber Substances 0.000 abstract description 4
- 238000010438 heat treatment Methods 0.000 abstract description 4
- 238000010586 diagram Methods 0.000 description 9
- 239000004925 Acrylic resin Substances 0.000 description 2
- 230000005540 biological transmission Effects 0.000 description 2
- 230000007423 decrease Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 230000000644 propagated effect Effects 0.000 description 2
- 238000003848 UV Light-Curing Methods 0.000 description 1
- 230000002238 attenuated effect Effects 0.000 description 1
- 230000000052 comparative effect Effects 0.000 description 1
- UHESRSKEBRADOO-UHFFFAOYSA-N ethyl carbamate;prop-2-enoic acid Chemical compound OC(=O)C=C.CCOC(N)=O UHESRSKEBRADOO-UHFFFAOYSA-N 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
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
- G02B6/02047—Dual mode fibre
Abstract
Description
【発明の詳細な説明】
（産業上の利用分野）
本発明は光ファイバが布設されている周囲の温度変化及
びその温度変化の位置を検知できるようにした２コア型
温度検知光ファイバに関するもの（従来の技術）
電カケープル等の長尺な線状体の部分的な温度上昇を監
視する方法として、従来は第８図に示すような構造の２
コア型温度検知光ファイバが用いられていた。この２コ
ア型温度検知光ファイバＡは、クラッドＢ内に同クラッ
ドＢより屈折率の高い第１のコアＣと、クラッドＢより
屈折率の高い第２のコアＤとが相互に隣接して並設され
ている。DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a two-core temperature sensing optical fiber that is capable of detecting temperature changes in the environment around which the optical fiber is installed and the position of the temperature changes. Prior Art) As a method for monitoring the local temperature rise of a long linear body such as an electric cable, conventionally a two-way system with a structure as shown in Fig. 8 has been used.
A core-type temperature sensing optical fiber was used. This two-core temperature sensing optical fiber A has a cladding B in which a first core C having a higher refractive index than the cladding B and a second core D having a higher refractive index than the cladding B are arranged adjacent to each other. It is set up.
この２コア型温度検知光ファイバＡでは、第１のコアＣ
及び第２のコアＤとクラッドＢとの屈折率差、第１のコ
アＣと第２のコアＤの外径、第１のコアＣと第２のコツ
Ｄ間の距離を最適に選ぶことにより、第１のコアＣと第
２のコアＤとが光結合し、第１のコアＣの一端より入射
した光Ｅが同コアＣと第２のコツＤ間を第８図の１０の
ように波状に往復しながら伝播される。In this two-core temperature sensing optical fiber A, the first core C
By optimally selecting the refractive index difference between the second core D and the cladding B, the outer diameter of the first core C and the second core D, and the distance between the first core C and the second tip D. , the first core C and the second core D are optically coupled, and the light E entering from one end of the first core C passes between the core C and the second core D as shown in 10 in Fig. 8. It is propagated back and forth in a wave-like manner.
また、同光ファイバへの長さを、第１のコアＣからの出
射光の強度が最大になるように、即ち、結合長（往復の
ピッチ）の整数倍に切断しておき、同光ファイバＡの一
部が何等かの原因（第９図の場合はヒーターＨ）により
加熱されると、光の結合状態が第９図のＩの部分で変化
して同図１１の波状になり、光の一部Ｇが第２のコアＤ
に結合した状態で出射し、第１のコアＣからの出射光Ｆ
の強度が減少する。従って第１のコアＣ及び第２のコア
Ｄからの出射光Ｇ、Ｆの増減を検知することにより、２
コア型温度検知光ファイバＡの一部に加えられた加熱状
態を検知することができる。In addition, the length of the optical fiber is cut so that the intensity of the light emitted from the first core C is maximized, that is, an integral multiple of the coupling length (round-trip pitch). When a part of A is heated by some cause (heater H in the case of Fig. 9), the coupling state of light changes at part I in Fig. 9, becoming wavy as shown in Fig. 11, and the light A part G of the second core D
The output light F from the first core C is emitted in a state of being coupled to
intensity decreases. Therefore, by detecting the increase/decrease in the emitted light G, F from the first core C and the second core D, 2
The heating state applied to a portion of the core type temperature sensing optical fiber A can be detected.
（従来技術の問題点）
前記のような構造の２コア型温度検知光ファイバは、温
度変化の有無を検知することはできるが温度変化した位
置（場所）を検知することはできないという難点があっ
た。(Problems with the prior art) The two-core temperature sensing optical fiber having the structure described above has the disadvantage that although it can detect the presence or absence of a temperature change, it cannot detect the position (place) where the temperature has changed. Ta.
（発明の目的）
本発明の目的は、温度変化の有無はもちろんのこと、温
度変化の位置も検知可能な２コア型温度検知光ファイバ
を提供することにある。(Objective of the Invention) An object of the present invention is to provide a two-core temperature sensing optical fiber that can detect not only the presence or absence of a temperature change but also the position of a temperature change.
（問題点を解決するための手段）
本発明の２コア型温度検知光ファイバは第１図、第２図
のように、光ファイバｌのクラッド２内に第１のコア３
と第２のコア４とが相互に隣接して並設され、この２つ
のコア３，４の夫々の外径、相互の距離及び屈折率差が
使用する光の波長において光結合するように設定され、
光ファイバｌの周囲の温度変化による２つのコア３．４
間の光結合の変化から、光ファイバｌの周囲の温度を検
知できるようにした２コア型温度検知光ファイバにおい
て、前記２つのコア３．４のうちのいずれか一方（第１
図、第２図では第１のコア３）が偏波保持性を有する構
造のものであることを特徴とするものである。(Means for Solving the Problems) As shown in FIGS. 1 and 2, the two-core temperature sensing optical fiber of the present invention has a first core 3 in the cladding 2 of the optical fiber l.
and a second core 4 are arranged adjacent to each other in parallel, and the respective outer diameters, mutual distances, and refractive index differences of these two cores 3 and 4 are set to optically couple at the wavelength of the light used. is,
Two cores due to temperature changes around the optical fiber 3.4
In a two-core temperature sensing optical fiber that can detect the temperature around the optical fiber l from changes in optical coupling between the two cores, one of the two cores (first
2, the first core 3) is characterized by having a polarization-maintaining structure.
（作用）
本発明の一実施例である第１図、第２図の２コア型温度
検知光ファイバは、第１のコア３を偏波保持性を有する
公知の楕円コアファイバとし、その短径方向を同コア３
の中心と第２のコア４の中心を結ぶ線と一致させたもの
である。この構造の２コア型温度検知光ファイバでは、
第１のコア３の長径長と短径長、第２のコア４の外径、
第１のコア３及び第２のコア４とクラッドｌとの屈折率
差及び第１のコア３と第２のコア４間の距離を最適に選
び、第１図、第２図のように第１のコア３の短径方向を
Ｙ軸、それと直角な長軸方向をＸ軸とすると、Ｙ軸方向
の偏波成分光は結合状態となり、第１のコア３の一端か
ら入射された光Ｅは第１のコア３と第２のコア４間を第
２図の２０の波状に往復して伝播するが、Ｘ軸方向の偏
波成分光は結合せず第２図の２１のように第１のコア３
内だけを伝播する。(Function) In the two-core temperature sensing optical fiber shown in FIGS. 1 and 2, which is an embodiment of the present invention, the first core 3 is a known elliptical core fiber having polarization maintaining property, and its short diameter Same direction as core 3
and the center of the second core 4. In this structure of two-core temperature sensing optical fiber,
The major axis length and minor axis length of the first core 3, the outer diameter of the second core 4,
The refractive index difference between the first core 3 and the second core 4 and the cladding l and the distance between the first core 3 and the second core 4 are optimally selected, and the If the short axis direction of the first core 3 is the Y axis, and the long axis direction perpendicular to that is the X axis, the polarized light components in the Y axis direction are in a coupled state, and the light E incident from one end of the first core 3 propagates back and forth between the first core 3 and the second core 4 in the form of waves 20 in FIG. 2, but the polarized component light in the 1 core 3
Propagate only within.
この状態の２′：Ｌア型温度検知光ファイバの一部が何
等かの原因（第３図の場合はヒーター５）により加熱さ
れると、その部分の熱膨張等により結合長が変化し、結
合光の伝播路は同図の２２の波状に変化する。このため
第２図のように偏波結合した状態の２コア型温度検知光
ファイバの第１のコア３に、その入射端からパルス光Ｅ
を入射し、パルス光の消灯時に入射端に帰ってくる後方
散乱光の強度を測定すると、その強度と時間との関係は
第４図、第５図のようになる。2': In this state, when a part of the LA-type temperature sensing optical fiber is heated by some cause (heater 5 in the case of Figure 3), the coupling length changes due to thermal expansion of that part, etc. The propagation path of the coupled light changes in the waveform 22 in the figure. Therefore, as shown in Fig. 2, the pulsed light E
When the intensity of the backscattered light that returns to the input end when the pulsed light is turned off is measured, the relationship between the intensity and time is as shown in FIGS. 4 and 5.
即ち、Ｘ軸方向では第１のコア３と第２のコア４間で光
結合しないため、第２図の２コア型温度検知光ファイバ
の一端より入射したパルス光ＥのＸ軸側波成分光は、第
２図の２１のように第１のコア３をその光フアイバ固有
の伝送ロスを生じながら伝播する。その際、レーリー散
乱等の後方散乱光が生じ、この後方散乱光のＸ軸側波成
分光は、第１のコア３中を同ファイバ固有の伝送ロスを
生じながら同コア３の入射端へ逆伝播される。That is, since there is no optical coupling between the first core 3 and the second core 4 in the X-axis direction, the X-axis sidewave component light of the pulsed light E incident from one end of the two-core temperature sensing optical fiber in FIG. The light beam propagates through the first core 3 as shown at 21 in FIG. 2 while causing a transmission loss inherent to the optical fiber. At this time, backscattered light such as Rayleigh scattering occurs, and the X-axis sidewave component light of this backscattered light travels back through the first core 3 to the input end of the core 3 while causing a transmission loss inherent to the fiber. Propagated.
これを図示されていないハーフミラ−等により受光器に
導き、その強度とパルス光入射時と受光時の時間との関
係を求めると第４図の２３のようになる。即ち、入射端
に近い部分の後方散乱光は伝播路が短い為比較的減衰せ
ず、また短時間後に受光器に到着し、入射端に遠い部分
からの後方散乱光は伝播路が長い為比較的減衰し、また
長時間後に受光器に到着する。このため後方散乱光のＸ
軸側波成分光の第１のコア３からの出射強度と時間との
関係は、第４図の２３のように右下りの略直線となる。If this is guided to a light receiver by a half mirror (not shown) or the like, and the relationship between its intensity and the time of pulse light incidence and light reception is determined, the result will be as shown at 23 in FIG. In other words, the backscattered light from the part near the input end has a short propagation path, so it is relatively not attenuated, and it arrives at the receiver after a short time, while the backscattered light from the part far from the input end has a long propagation path, so it is relatively unattenuated. The light attenuates and reaches the receiver after a long period of time. Therefore, the backscattered light
The relationship between the output intensity of the axial sidewave component light from the first core 3 and time is a substantially straight line descending to the right, as shown by 23 in FIG.
一方、後方散乱光のＹ軸偏波成分光は、第１のコア３と
第２のコア４間を往復しつつ両光ファイバ３，４中を逆
伝播して入射端に戻る。このとき、入射端から結合長の
整数倍の位置からの後方散乱光の殆どは第１のコア３よ
り出射されるが、結合長の整数＋０．５倍の位置からの
後方散乱光の大部分は第２のコア４より出射され、第１
のコア３からは殆ど出射されない、従って後方散乱光の
Ｙ軸偏波成分光の第１のコア３からの出射強度と時間の
関係は第４図の２４のような波状になる。従って、入射
パルス光のＸ軸偏波成分光に起因する後方散乱光の、第
１のコア３からの出射強度と時間との関係は第４図の２
３の直線と２４の波形とを加えた同図の２５の波状にな
る。On the other hand, the Y-axis polarized component light of the backscattered light travels back and forth between the first core 3 and the second core 4, back propagates through both optical fibers 3 and 4, and returns to the input end. At this time, most of the backscattered light from a position that is an integral multiple of the coupling length from the input end is emitted from the first core 3, but most of the backscattered light from a position that is an integral number + 0.5 times the coupling length from the input end. is emitted from the second core 4, and
Therefore, the relationship between the intensity of the Y-axis polarized component light of the backscattered light emitted from the first core 3 and time is wave-like as shown at 24 in FIG. Therefore, the relationship between the output intensity of the backscattered light from the first core 3 due to the X-axis polarized component light of the incident pulsed light and time is 2 in FIG.
The wavy shape 25 in the figure is obtained by adding the straight line 3 and the waveform 24.
一方、入射パルス光のＹ軸偏波成分光は第２図の２０の
ように第１のコア３と第２のコア４間を往復しつつ波状
に伝播する。その際生じる後方散乱光のうちＹ軸成分光
は、パルス光のＹ軸成分光と同一の伝播路を逆伝播して
入射端に到り、全てのＹ軸成分光が第１のコア３で受光
できる為、その強度と時間との関係は第５図の２６のよ
うに右下りの略直線となる。On the other hand, the Y-axis polarized component light of the incident pulsed light propagates in a waveform while reciprocating between the first core 3 and the second core 4 as shown at 20 in FIG. Of the backscattered light generated at this time, the Y-axis component light propagates back through the same propagation path as the Y-axis component light of the pulsed light and reaches the input end, so that all the Y-axis component light reaches the first core 3. Since light can be received, the relationship between its intensity and time is a substantially straight line descending to the right, as shown by 26 in FIG.
一方、後方散乱光のＸ軸成分光は第１のコア３内で生じ
たもののみが同コア３内を逆伝播して入射端に到る為、
その強度と時間との関係は第５図の２７の波状になる。On the other hand, since only the X-axis component light of the backscattered light generated within the first core 3 propagates back inside the core 3 and reaches the input end,
The relationship between the intensity and time is wave-like as shown in 27 in FIG.
従って入射パルス光のＹ軸成分光に起因する全ての後方
散乱光の第１のコア３からの出射強度と時間との関係は
第５図の２６の直線と２７の波とを加えた２８のような
波状になる。Therefore, the relationship between the output intensity of all backscattered light from the first core 3 due to the Y-axis component light of the incident pulsed light and time is 28, which is the sum of the 26 straight lines and 27 waves in FIG. It becomes wavy.
従って第１のコア３に無偏光のパルス光を入射したとき
に、第１のコア３に戻ってくる全ての後方散乱光強度と
時間の関係は、第４図の２５の波と第５図の２８の波と
を加えた第６図のような波になり、横軸（時間）が後方
散乱光の発生位置即ち入射端からの距離に比例する。Therefore, when non-polarized pulsed light is incident on the first core 3, the relationship between the intensity and time of all the backscattered light that returns to the first core 3 is as follows: wave 25 in Figure 4 and wave 5 in Figure 5. The result is a wave as shown in FIG. 6, where the horizontal axis (time) is proportional to the generation position of the backscattered light, that is, the distance from the incident end.
この状態の２コア型温度検知光ファイバが何等かの原因
（第３図の場合はヒーター５）により加熱されると、加
熱された部分の第１のコア３と第２のコア４の結合長が
第３図の６のようにＹ軸成分光の伝播路が変化する。従
って入射端よりパルス光Ｅを入射したときの、第１のコ
ア３で受光する後方散乱光の強度と時間との関係は第７
図のようになり、加熱された部分の結合長の変化が同図
の３１のように表れる。従って加熱の有無だけでなく、
加熱位置の同定も可能となる。When the two-core temperature sensing optical fiber in this state is heated by some cause (heater 5 in the case of Fig. 3), the coupling length between the first core 3 and second core 4 in the heated part increases. However, as shown in 6 in FIG. 3, the propagation path of the Y-axis component light changes. Therefore, when the pulsed light E is input from the input end, the relationship between the intensity and time of the backscattered light received by the first core 3 is as follows.
As shown in the figure, the change in bond length of the heated portion appears as shown in 31 in the figure. Therefore, in addition to the presence or absence of heating,
It also becomes possible to identify the heating position.
（実施例）
第１図、第２図は本発明の２コア型温度検知光ファイバ
の一実施例である。この光ファイバは外径１２５ｕｍの
クラッド２のほぼ中央に、同クラッド２との屈折率差０
．４５％、短径長０．８７μｍ、長径長２．４２μｍの
楕円形の第１のコア３が配置され、同コア３の中心から
１５μｍ離れた位置に中心が（るように第２のコア４が
配置され、同コア４はクラッド２との屈折率差０．４５
％、外径０．８７μｍであり、クラッド２の周囲に紫外
線硬化型ウレタンアクリレート樹脂が厚さ９０μｍに被
覆された、長さ１０００ｍのものである。(Example) FIGS. 1 and 2 show an example of the two-core temperature sensing optical fiber of the present invention. This optical fiber is placed approximately in the center of the cladding 2 with an outer diameter of 125 um, with a refractive index difference of 0 between the cladding 2 and the cladding 2.
．． 45%, an elliptical first core 3 with a minor axis length of 0.87 μm and a major axis length of 2.42 μm is arranged, and the second core 4 is placed so that its center is 15 μm away from the center of the core 3. is arranged, and the core 4 has a refractive index difference of 0.45 with the cladding 2.
%, an outer diameter of 0.87 μm, a cladding 2 surrounded by an ultraviolet curable urethane acrylate resin coated to a thickness of 90 μm, and a length of 1000 m.
この２コア型温度検知光ファイバを室温に保持し、その
一部分を電気ヒータで１２０℃に加熱した。この状態の
２コア型温度検知光ファイバの第１のコア３の入射端に
、レーザーダイオードにより１．３ｕｍのパルス光を入
射し、第１のコア３の後方散乱光をハーフミラ−で受光
器に導き、その強度と時間の関係を求めたところ、１２
０℃に加熱した部分に相当する時間の部分は第７図の３
１の部分のように山谷のピッチが変化し、加熱された部
分（位置）を検知することができた。This two-core temperature sensing optical fiber was maintained at room temperature, and a portion of it was heated to 120° C. with an electric heater. A 1.3 um pulsed light is inputted from a laser diode into the input end of the first core 3 of the two-core temperature sensing optical fiber in this state, and the backscattered light from the first core 3 is sent to a receiver using a half mirror. When we calculated the relationship between the strength and time of the guidance, we found that 12
The time period corresponding to the part heated to 0℃ is 3 in Figure 7.
As shown in part 1, the pitch of the peaks and valleys changed, making it possible to detect the heated part (position).
比較例として第８図に示す従来構造の２コア型温度検知
光ファイバにおいて、外径１２５μｍのクラッド２のほ
ぼ中央に、同クラッド２との屈折率差０．３８％、外径
０．８７μｍの第１のコア３が配置され、同コア３の中
心から１５μｍｌｉれた位置に中心がくるように第２の
コア４が配置され、同コア４はクラッド２との屈折率差
０．３８％、外径０．８７μｍであり、クラッド２の周
囲に紫外線硬化型つＩノタンアクリレート樹脂が厚さ９
０μｍに被覆され、長さが１０００ｍの２コア型温度温
度検知光ファイバを用意し、その全長を室温に保持した
ときと、そめ一部分を１２０℃に加熱したときの後方散
乱光の強度と時間の関係を実施例と同様に求めた。いず
れの場合も第１Ｏ図に示すような略直線となり、加熱部
分を検知することができなかった。As a comparative example, in a conventional two-core temperature sensing optical fiber shown in FIG. The first core 3 is arranged, and the second core 4 is arranged so that its center is located 15 μmli away from the center of the first core 3, and the core 4 has a refractive index difference of 0.38% with the cladding 2. The outer diameter is 0.87 μm, and the UV-curing type I-notane acrylate resin is coated around the cladding 2 with a thickness of 9 μm.
A two-core temperature-sensing optical fiber coated with 0 μm and 1000 m in length was prepared, and the intensity and time of backscattered light were measured when the entire length was kept at room temperature and when a part of the fiber was heated to 120°C. The relationship was determined in the same manner as in the example. In either case, the curve was a substantially straight line as shown in FIG. 1O, and the heated portion could not be detected.
尚、図示した第１図、第２図の実施例は、楕円形偏波保
持型の第１のコア３の短軸方向を、第１のコア３と第２
のコア４の中心を結ぶ軸と一致させた構造の場合である
が、本発明では第１のコア３を図示した状態より９０°
回転させた構造のものであってもよく、その場合も前記
実施例の場合と同様の効果が得られる。In the illustrated embodiments of FIGS. 1 and 2, the short axis direction of the elliptical polarization-maintaining first core 3 is aligned with the first core 3 and the second core 3.
However, in the present invention, the first core 3 is aligned at an angle of 90° from the illustrated state.
It may also have a rotated structure, and in that case also the same effects as in the above embodiment can be obtained.
また、楕円形の第１のコア３と、円形の第２のコア４と
の位置関係は特に限定する必要がなく、円形の第２のコ
ア４がクラッド２のほぼ中央にある構造でもよい。Further, the positional relationship between the elliptical first core 3 and the circular second core 4 does not need to be particularly limited, and a structure in which the circular second core 4 is located approximately in the center of the cladding 2 may be used.
また、パルス光を入射して後方散乱光を検出するコアも
、楕円形の第１のコア３に限定する必要はなく、円形の
第２のコア４であっても良い。Furthermore, the core through which the pulsed light is incident and the backscattered light is detected need not be limited to the elliptical first core 3, and may be the circular second core 4.
（発明の効果）
本発明の２コア型温度検知光ファイバによれば、従来構
造の２コア型温度検知光ファイバと同様に温度検知がで
きるのは勿論、従来構造の同光ファイバでは不可能であ
った温度変化部の位置を検知することもできる。(Effects of the Invention) According to the two-core temperature sensing optical fiber of the present invention, it is possible to perform temperature detection in the same way as the two-core temperature sensing optical fiber with the conventional structure, but it is also possible to detect temperature in a way that is not possible with the same optical fiber with the conventional structure. It is also possible to detect the location of the temperature change area.
第１図は本発明の２コア型温度検知光ファイバの断面図
、第２図は同光ファイバの光の伝播状態の説明図、第３
図は同光ファイバの高温検知時の光の伝播状態の説明図
、第４図は本発明の２コア型温度検知光ファイバの結合
しない偏波成分光の後方散乱光強度と時間との関係を示
す説明図、第５図は第２図の光結合時の偏波成分光の後
方散乱光強度と時間との関係を示す説明図、第６図は第
２図の第１のコアの後方散乱光強度と時間との関係を示
す説明図、第７図は第３図の第１のコアの後方散乱光強
度と時間との関係を示す説明図、第８図は従来の２コア
型温度検知光ファイバの説明図、第９図は同光ファイバ
の高温検知時の光の伝播状態の説明図、第１Ｏ図は同光
ファイバの加熱時の後方散乱光強度と時間との関係を示
す説明図である。
ｌは光ファイバ
２はクラッド
３は第１のコア
４は第２のコアFIG. 1 is a cross-sectional view of the two-core temperature sensing optical fiber of the present invention, FIG. 2 is an explanatory diagram of the state of light propagation in the same optical fiber, and FIG.
The figure is an explanatory diagram of the light propagation state during high temperature detection in the same optical fiber, and Figure 4 shows the relationship between the backscattered light intensity and time of the uncoupled polarized component light of the two-core temperature sensing optical fiber of the present invention. 5 is an explanatory diagram showing the relationship between the backscattered light intensity of the polarized component light during optical coupling in FIG. 2 and time, and FIG. 6 is the backscattering of the first core in FIG. 2. An explanatory diagram showing the relationship between light intensity and time. Figure 7 is an explanatory diagram showing the relationship between the backscattered light intensity of the first core in Figure 3 and time. Figure 8 is a conventional two-core temperature detection diagram. An explanatory diagram of the optical fiber, Fig. 9 is an explanatory diagram of the propagation state of light when the optical fiber detects a high temperature, and Fig. 1O is an explanatory diagram showing the relationship between backscattered light intensity and time when the optical fiber is heated. It is. l is the optical fiber 2 is the cladding 3 is the first core 4 is the second core
Claims (1)
ア４とが相互に隣接して並設され、この２つのコア３、
４の夫々の外径、相互の距離及び屈折率差は使用する光
の波長において光結合するように設定され、光ファイバ
１の周囲の温度変化による２つのコア３、４間の光結合
の変化から、光ファイバ１の周囲の温度を検知できるよ
うにした２コア型温度検知光ファイバにおいて、前記２
つのコア３、４のうちいずれか一方が偏波保持性を有す
る構造のものであることを特徴とする２コア型温度検知
光ファイバ。A first core 3 and a second core 4 are arranged adjacent to each other in a cladding 2 of an optical fiber 1, and these two cores 3,
The outer diameters, mutual distances, and refractive index differences of each of the cores 4 are set to optically couple at the wavelength of the light used, and changes in the optical coupling between the two cores 3 and 4 due to changes in the temperature around the optical fiber 1. In the two-core temperature sensing optical fiber that is capable of detecting the temperature around the optical fiber 1,
A two-core temperature sensing optical fiber characterized in that one of the two cores 3 and 4 has a polarization-maintaining structure.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1001492A JPH02181708A (en) | 1989-01-07 | 1989-01-07 | Two core type temperature detecting optical fiber |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1001492A JPH02181708A (en) | 1989-01-07 | 1989-01-07 | Two core type temperature detecting optical fiber |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02181708A true JPH02181708A (en) | 1990-07-16 |
Family
ID=11502952
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP1001492A Pending JPH02181708A (en) | 1989-01-07 | 1989-01-07 | Two core type temperature detecting optical fiber |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02181708A (en) |
Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103134533A (en) * | 2011-12-02 | 2013-06-05 | 西安金和光学科技有限公司 | Distributed optical fiber sensing device based on dual-channel and operation method thereof |
| JP2014517936A (en) * | 2011-05-19 | 2014-07-24 | インジェネリック・ゲゼルシャフト・ミット・ベシュレンクテル・ハフツング | Optical waveguide coupling device |
| JP2014228705A (en) * | 2013-05-22 | 2014-12-08 | 三菱電線工業株式会社 | Multi-core optical fiber and method for manufacturing the same |
| US9002149B2 (en) | 2008-11-12 | 2015-04-07 | Fotech Solutions Limited | Distributed fibre optic sensing for event detection |
| JP2015099211A (en) * | 2013-11-18 | 2015-05-28 | 株式会社フジクラ | Multi-core fiber |
-
1989
- 1989-01-07 JP JP1001492A patent/JPH02181708A/en active Pending
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9002149B2 (en) | 2008-11-12 | 2015-04-07 | Fotech Solutions Limited | Distributed fibre optic sensing for event detection |
| JP2014517936A (en) * | 2011-05-19 | 2014-07-24 | インジェネリック・ゲゼルシャフト・ミット・ベシュレンクテル・ハフツング | Optical waveguide coupling device |
| CN103134533A (en) * | 2011-12-02 | 2013-06-05 | 西安金和光学科技有限公司 | Distributed optical fiber sensing device based on dual-channel and operation method thereof |
| WO2013079027A1 (en) * | 2011-12-02 | 2013-06-06 | 西安金和光学科技有限公司 | Distributed fibre sensing device based on dual channel and running method thereof |
| JP2014228705A (en) * | 2013-05-22 | 2014-12-08 | 三菱電線工業株式会社 | Multi-core optical fiber and method for manufacturing the same |
| JP2015099211A (en) * | 2013-11-18 | 2015-05-28 | 株式会社フジクラ | Multi-core fiber |
| US9470840B2 (en) | 2013-11-18 | 2016-10-18 | Fujikura Ltd. | Multicore fiber |
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