JPS5853243A - Light transmitting system - Google Patents
Light transmitting systemInfo
- Publication number
- JPS5853243A JPS5853243A JP56150633A JP15063381A JPS5853243A JP S5853243 A JPS5853243 A JP S5853243A JP 56150633 A JP56150633 A JP 56150633A JP 15063381 A JP15063381 A JP 15063381A JP S5853243 A JPS5853243 A JP S5853243A
- Authority
- JP
- Japan
- Prior art keywords
- light
- optical fiber
- optical
- fiber
- stokes
- 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
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/29—Repeaters
- H04B10/291—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form
- H04B10/2912—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form characterised by the medium used for amplification or processing
- H04B10/2916—Repeaters in which processing or amplification is carried out without conversion of the main signal from optical form characterised by the medium used for amplification or processing using Raman or Brillouin amplifiers
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/30—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range using scattering effects, e.g. stimulated Brillouin or Raman effects
- H01S3/302—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range using scattering effects, e.g. stimulated Brillouin or Raman effects in an optical fibre
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Plasma & Fusion (AREA)
- Optics & Photonics (AREA)
- Light Guides In General And Applications Therefor (AREA)
- Optical Communication System (AREA)
Abstract
Description
【発明の詳細な説明】
を利用して長距離の光伝送を可能ならしめる光伝送方式
に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical transmission system that makes long-distance optical transmission possible using .
従来の光伝送方式においては、半導体レーザへの注入電
流に信号を載せて直接半導体レーザ全変Cノ)
調するか、半導体V−ザや固体レーザ全通続発振させて
、そのレーザ光i LiNbO2やに.DP結晶等から
なる外部変調器で変調し、その変調出力光を光ファイバ
に導入する方法をとっていた。これらの方法では、光フ
アイバ出射端での光パワーレベルは、光ファイバの損失
と入射端光フアイバ内の光パワーレベルで決定され、敷
設できる光ファイバ長が決定される。そして、長距離の
光伝送を実現するためには中継器または光増幅器が必要
である。In conventional optical transmission systems, a signal is added to the current injected into the semiconductor laser to directly tune the semiconductor laser, or a semiconductor laser or solid-state laser is continuously oscillated to transmit the laser light iLiNbO2. Yani. The method used was to modulate the light using an external modulator such as a DP crystal, and then introduce the modulated output light into an optical fiber. In these methods, the optical power level at the output end of the optical fiber is determined by the loss of the optical fiber and the optical power level within the input end optical fiber, and the length of the optical fiber that can be installed is determined. In order to realize long-distance optical transmission, repeaters or optical amplifiers are required.
中継器は光検出器と光源ならびに電子回路から成り、中
継器内では光は電気信号に変換され、再び光にもどる過
程があるので、実装上複雑になる。A repeater consists of a photodetector, a light source, and an electronic circuit. Inside the repeater, light is converted into an electrical signal and then converted back into light again, making it complex to implement.
光増幅器は将来の光伝送において不可欠と考えられてい
るが、実用的な光増幅器は未だ実現されていない。原理
的に検討されている半導体璽一V族のダブルへテロ構造
の光増幅器には雑音の問題があり、光ファイバと光増幅
器の接続が困難であるなど、未だ多くの問題点を有する
。Although optical amplifiers are considered essential for future optical transmission, practical optical amplifiers have not yet been realized. The semiconductor group V double heterostructure optical amplifier that has been studied in principle still has many problems, such as noise and difficulty in connecting the optical fiber and the optical amplifier.
本発明の目的は、このような問題点全解決して全く新し
い光伝送方式を提供することにあり、そ(2)
のために本発明では、光フアイバ内で生じる非線形現象
を利用して、進行波的光増幅機能を持たせることにより
長距離光伝送を実現する。The purpose of the present invention is to solve all of these problems and provide a completely new optical transmission system.To achieve this goal (2), the present invention utilizes nonlinear phenomena that occur within optical fibers to Long-distance optical transmission is realized by providing a wave-like optical amplification function.
以下に図面を参照して本発明の詳細な説明する。The present invention will be described in detail below with reference to the drawings.
第1図は本発明による光伝送方式の構成例を示し、ここ
でlはストークス光に相当する光源、2≠およびjはレ
ンズ、乙は3 dB光結合器または分岐路形合流器、7
およびgは光ファイバである。FIG. 1 shows a configuration example of an optical transmission system according to the present invention, where l is a light source corresponding to Stokes light, 2≠ and j are lenses, O is a 3 dB optical coupler or branch type combiner, and 7
and g is an optical fiber.
光フアイバ内における誘導ラマンによって生じるストー
クス光のパワーPa(L)は、近似的に、Pa(L)
= Ps(o) eGPpI′/’ (1)
と表わされる。ここで、Lは光ファイバの実効長であり
、
r、=(/e ”)/α (2)で表わ
される。なお、Ps(0)は光フアイバ入射端における
ストークス光のパワー、lは光ファイバ長さ、αは光フ
ァイバの損失、Gは誘導ラマン利得、Ppはポンピング
光のパワー、A ハ光7アイバのコアの実効的面積であ
る。The power Pa(L) of Stokes light generated by stimulated Raman in an optical fiber is approximately expressed as Pa(L)
= Ps(o) eGPpI'/' (1)
It is expressed as Here, L is the effective length of the optical fiber and is expressed as r, = (/e'')/α (2). In addition, Ps (0) is the power of Stokes light at the input end of the optical fiber, and l is the power of the Stokes light at the input end of the optical fiber. α is the fiber length, α is the loss of the optical fiber, G is the stimulated Raman gain, Pp is the power of the pumping light, and A is the effective area of the core of the optical 7-eye fiber.
ここで、第1図に示すように信号により変1!さオtた
信号光として光ファイバ7を伝搬したストークス光が/
θμw (−X) dBm )のパワーで出射したとす
る。理想的な仮定として、光ファイバ7と分岐路形合流
器6および光ファイバrとの間では接続損失および伝搬
損失が写とすれは、Pa(0)=/θμWとなる。今、
光ファイバの損失α−0,/21an−’(θ:jan
/7I2+) 、 il = 3θ/i、A=4’X/
θ cffl(7≠wコア)、G、、、、0.92×/
θ cIIL/ w (Y、 5asaki他:Ele
ctronics Letter 、 Vol、 /
7. f’h I 、 pp、 3/j −3/A(
/911)参照)として、Ps(L) / Ps(O)
= /、 2となるPp k求めてみると、ppmり
&mwとなる。すなわち、光ファイバtの出射端でパワ
ー12μwを得るには、ポンピング光のパワーはりAm
wでよいことになる。この値は理想的な場合であるから
、必要なポンピング光のパワーは実際にはもつと大きい
と考えられる。以上述べたように、光ファイバ7を通じ
て伝送された信号光は微弱化しているが、ポンピング光
を導入することによって光ファイバrでは再び増幅され
て伝送される。Here, as shown in FIG. 1, the signal changes to 1! The Stokes light propagated through the optical fiber 7 as a signal light is /
Suppose that it is emitted with a power of θμw (-X) dBm). As an ideal assumption, the connection loss and propagation loss between the optical fiber 7, the branch type combiner 6, and the optical fiber r become Pa(0)=/θμW. now,
Optical fiber loss α-0,/21an-' (θ:jan
/7I2+), il = 3θ/i, A=4'X/
θ cffl (7≠w core), G, , 0.92×/
θ cIIL/w (Y, 5asaki et al.: Ele
ctronics Letter, Vol, /
7. f'h I, pp, 3/j -3/A(
/911)), Ps(L) / Ps(O)
= /, 2 When Pp k is found, it becomes ppm ri&mw. That is, in order to obtain a power of 12 μw at the output end of the optical fiber t, the power of the pumping light is Am
W is a good thing. Since this value is an ideal case, it is considered that the necessary power of the pumping light is actually large. As described above, the signal light transmitted through the optical fiber 7 is weakened, but by introducing the pumping light, it is amplified again and transmitted through the optical fiber r.
第2図はポンピング光の角周波数tωpとしてYAGレ
ーザのQスイッチモードロック光(波長/、 0611
m ) f Jj IgB O)I vAD光ファイバ
に導入した時のストークス光の励起状況を示す。波長/
、06μmより長い波長側のスペクトラムは高次のスト
ークス光が励起された状況を示し、i、otμmより短
い波長側のスペクトラムは反ストークス光の励起を示す
。これから分かるように、ストークス光のスペクトラム
の幅はポンピング光に比べて広い。これは第1図に示す
ような増幅すべきストークス光とポンピング光の波長の
許容幅が広い、すなわち波長の制御性は厳しくないこと
がわかる。Figure 2 shows the Q-switch mode-locked light (wavelength/, 0611
m ) f Jj IgB O)I The excitation state of Stokes light when introduced into the vAD optical fiber is shown. wavelength/
The spectrum on the wavelength side longer than , 06 μm indicates the excitation of higher-order Stokes light, and the spectrum on the wavelength side shorter than i,ot μm indicates the excitation of anti-Stokes light. As can be seen, the spectrum width of Stokes light is wider than that of pumping light. This shows that the allowable wavelength range of the Stokes light and pumping light to be amplified is wide as shown in FIG. 1, that is, the wavelength controllability is not strict.
誘導ラマン発振におけるポンピング光の波長λpとスト
ークス光の波長λBとの関係はλS=λp/(/±mΔ
νλp ) (3)で表わされろ。ここで
、mはストークス光の次数、(j)
Δνはストークス光の利得幅である。例えば、−次のス
ト=7.3+2μm
−ラス光を石英ファイバの零分散であるi摩Iτイ石英
ファイバではΔシー1110 cRであるから、2.=
/、24Iμmとなる。したがって、ストークス波とポ
ンピング光の波長の差が大きいので、光検出器側にフィ
ルタを装着すれば、ポンピング光ならびにこれに含まれ
るノイズを除去できる。これに対して、I−V族の半導
体光増幅器ではノイズ光の波長が信号光にほぼ重畳され
ているので、通常入手できるフィルタではノイズ光を除
去できない。The relationship between the wavelength λp of the pumping light and the wavelength λB of the Stokes light in stimulated Raman oscillation is λS=λp/(/±mΔ
νλp ) (3). Here, m is the order of Stokes light, and (j) Δν is the gain width of Stokes light. For example, - next strike = 7.3 + 2 μm - Since the laser beam has zero dispersion of the quartz fiber, Iτ, and the quartz fiber has ΔC of 1110 cR, 2. =
/, 24Iμm. Therefore, since the difference in wavelength between the Stokes wave and the pumping light is large, if a filter is attached to the photodetector side, the pumping light and the noise contained therein can be removed. On the other hand, in IV group semiconductor optical amplifiers, the wavelength of the noise light is almost superimposed on the signal light, so that the noise light cannot be removed with commonly available filters.
ポンピング光を連続発振させる理由は、ポンピング光と
ストークス光の群速度の違いがあるためで、信号光とし
てパルス化されたストークス光が、光フアイバ内のどこ
からでもポンピング光よりエネルギー供給されるように
するためである。また、ポンピング光のパワーは大きい
方がよいが、高次のストークス光の励起がないように、
しかも信号光がないときにはポンピング光のみでストー
クス光が励起されないように、ある範囲以下に抑えなけ
ればならない。The reason why the pumping light is continuously oscillated is because there is a difference in group velocity between the pumping light and the Stokes light, so that the pulsed Stokes light as the signal light is supplied with energy by the pumping light from anywhere within the optical fiber. This is to do so. In addition, the power of the pumping light should be large, but in order to avoid excitation of higher-order Stokes light,
Furthermore, when there is no signal light, the pumping light must be kept within a certain range so that the Stokes light is not excited by the pumping light alone.
以上示したように、光伝送路の速中の数個所に(、<)
第1図に示したように3dB光結合器あるいは分岐路形
合流器tを配置し、連続発振のポンピング光を導入して
合流することによって、ストークス光であるキャリア信
号光は途中に中継器全通さずとも長距離にわたって光フ
ァイバ内會伝送する。As shown above, 3 dB optical couplers or branch type combiners t are placed at several locations in the optical transmission line (, <) as shown in Figure 1, and continuous wave pumping light is introduced. By merging them together, the carrier signal light, which is Stokes light, can be transmitted within the optical fiber over a long distance without passing through a repeater all along the way.
なお、光源lおよび3としては固体レーザ、気体レーザ
、半導体レーザのいずれでもよいが、寿命および波長の
同調の点からは半導体レーザが好適である。Note that the light sources 1 and 3 may be solid-state lasers, gas lasers, or semiconductor lasers, but semiconductor lasers are preferred from the viewpoint of longevity and wavelength tuning.
以上説明したように、本発明によれば、入力信号光のパ
ワーが小さくても誘導ラマン利得によってポンピング光
の光エネルギー金光ファイバ内で進でテ波的に吸収して
増幅できるので、長距離光伝送が可能になる。しかも、
本発明光伝送方式の構成は極めて簡単で、ポンピング光
の光源駆動は直流電諒でよいから電気回路としての複雑
さもな(、従って光伝送路の途中に配置するのに好都合
であり、さらにストークス光とポンピング光の波長の差
は大きいので光フィルタの製作も容易である。As explained above, according to the present invention, even if the power of the input signal light is small, the optical energy of the pumping light can be absorbed and amplified in the forward T wave manner within the gold optical fiber by the stimulated Raman gain, so that long-distance optical transmission becomes possible. Moreover,
The configuration of the optical transmission system of the present invention is extremely simple, and the light source for the pumping light can be driven by a DC voltage, so there is no complexity in the electrical circuit (therefore, it is convenient to place it in the middle of the optical transmission path, and it is also possible to use the Stokes optical Since there is a large difference in the wavelengths of the pumping light and the pumping light, it is easy to manufacture an optical filter.
第1図は本発明光伝送方式の一例を示す構成図、第2図
はYAGレーザ(波長10tμm)のポンピング光ωp
によって光フアイバ内で励起した誘導ラマンによる各ス
トークス光ω1.ω2.・・曲のスペクトラムを示す特
性曲線図である。
l・・・ストークス光に相当する光源、コ・・・信号源
、
3・・・ポンピング光に相当する光源、≠、j川レ用ズ
−
6・・・3dB光結合器または分岐路形合流器、7、g
・・・伝送路としての光ファイバ。
特許出願人 日本電信を話公社Figure 1 is a block diagram showing an example of the optical transmission system of the present invention, and Figure 2 is a pumping light ωp of a YAG laser (wavelength 10tμm).
Each Stokes beam ω1 due to stimulated Raman excited in the optical fiber by . ω2. ... is a characteristic curve diagram showing the spectrum of a song. l...Light source corresponding to Stokes light, Co...Signal source, 3...Light source corresponding to pumping light, ≠, vessel, 7, g
...Optical fiber as a transmission line. Patent applicant Nippon Telegraph Corporation
Claims (1)
クス光を信号光としてmJ記先光ファイバ伝送路導き、
該光フアイバ伝送路の途中に3dB光結合器あるいは分
岐路形合流器を配置して、前記誘導ラマン発振のための
連続発振ボンピング先光を前記ストークス光と合流して
前記ストークス光全増幅することにより前記信号光を伝
送することを特徴とする光伝送方式。Introducing Stokes light that undergoes stimulated Raman oscillation in the optical fiber transmission line as signal light to the mJ destination optical fiber transmission line,
A 3 dB optical coupler or a branch type combiner is disposed in the middle of the optical fiber transmission line, and the continuous oscillation pumping destination light for the stimulated Raman oscillation is combined with the Stokes light to fully amplify the Stokes light. An optical transmission method characterized in that the signal light is transmitted by.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP56150633A JPS5853243A (en) | 1981-09-25 | 1981-09-25 | Light transmitting system |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP56150633A JPS5853243A (en) | 1981-09-25 | 1981-09-25 | Light transmitting system |
Publications (1)
Publication Number | Publication Date |
---|---|
JPS5853243A true JPS5853243A (en) | 1983-03-29 |
Family
ID=15501114
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP56150633A Pending JPS5853243A (en) | 1981-09-25 | 1981-09-25 | Light transmitting system |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPS5853243A (en) |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0139081A2 (en) * | 1983-09-28 | 1985-05-02 | Polaroid Corporation | Optical communications system using raman repeaters and components therefor |
JPS60157279A (en) * | 1983-11-25 | 1985-08-17 | ザ・ボード・オブ・トラステイーズ・オブ・ザ・レランド・スタンフオード・ジュニア・ユニバーシテイ | Filber optical amplifier system and method of amplifying photosignal |
US5510931A (en) * | 1989-08-31 | 1996-04-23 | Fujitsu Limited | Optical amplifier and optical communication system with optical amplifier using pumping right beam |
Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS56165437A (en) * | 1980-05-26 | 1981-12-19 | Kokusai Denshin Denwa Co Ltd <Kdd> | Optical repeating system for optical communication |
-
1981
- 1981-09-25 JP JP56150633A patent/JPS5853243A/en active Pending
Patent Citations (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS56165437A (en) * | 1980-05-26 | 1981-12-19 | Kokusai Denshin Denwa Co Ltd <Kdd> | Optical repeating system for optical communication |
Cited By (7)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0139081A2 (en) * | 1983-09-28 | 1985-05-02 | Polaroid Corporation | Optical communications system using raman repeaters and components therefor |
JPS60157279A (en) * | 1983-11-25 | 1985-08-17 | ザ・ボード・オブ・トラステイーズ・オブ・ザ・レランド・スタンフオード・ジュニア・ユニバーシテイ | Filber optical amplifier system and method of amplifying photosignal |
US5510931A (en) * | 1989-08-31 | 1996-04-23 | Fujitsu Limited | Optical amplifier and optical communication system with optical amplifier using pumping right beam |
US5521737A (en) * | 1989-08-31 | 1996-05-28 | Fujitsu Limited | Optical amplifier and optical communication system with optical amplifier using pumping light beam |
US5526163A (en) * | 1989-08-31 | 1996-06-11 | Fujitsu Limited | Optical amplifier and optical communication system with optical amplifier using pumping light beam |
US5535050A (en) * | 1989-08-31 | 1996-07-09 | Fujitsu Limited | Optical amplifier and optical communication system with optical amplifier using pumping light beam |
US5546213A (en) * | 1989-08-31 | 1996-08-13 | Fujitsu Limited | Optical amplifier and optical communication system provided with the optical amplifier |
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