JPH0884135A - Wavelength multiplexed optical communication system - Google Patents
Wavelength multiplexed optical communication systemInfo
- Publication number
- JPH0884135A JPH0884135A JP6244690A JP24469094A JPH0884135A JP H0884135 A JPH0884135 A JP H0884135A JP 6244690 A JP6244690 A JP 6244690A JP 24469094 A JP24469094 A JP 24469094A JP H0884135 A JPH0884135 A JP H0884135A
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- Prior art keywords
- optical
- wavelength
- dispersion
- transmission line
- optical transmission
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Abstract
Description
【０００１】[0001]
【産業上の利用分野】本発明は、波長の異なる複数の光
送信信号を光伝送路を通して送信する波長多重光通信シ
ステムに関するものである。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a wavelength division multiplexing optical communication system for transmitting a plurality of optical transmission signals having different wavelengths through an optical transmission line.
【０００２】[0002]
【従来の技術】図４には一般的な波長多重光通信システ
ムの構成が示されている。同図において、送信側には、
複数の信号１〜Ｎを電気光変換器１によって各電気信号
１〜Ｎを波長λ1 〜λN の光送信信号（光パルス送信信
号）に変換し、これらの各光送信信号は光合波器２で合
波され、この合波された各波長λ1 〜λN の送信信号
は、光伝送路（光ファイバ）３を通して波長多重送信さ
れ、受信側で、光分波器４によって各波長λ1 〜λN の
光送信信号に分波して取り出される。そして、各波長λ
1 〜λN の光送信信号は光電気変換器５によって光信号
から電気信号に変換されて所望の信号処理が行われる。2. Description of the Related Art FIG. 4 shows the configuration of a general wavelength division multiplexing optical communication system. In the figure, on the transmitting side,
Converts each electric signals 1~N a plurality of signals 1~N by electrooptic converter 1 to an optical transmission signal of the wavelength lambda 1 to [lambda] N (optical pulse transmission signal), respective optical transmission signal of the optical multiplexer The multiplexed transmission signals of the respective wavelengths λ 1 to λ N are wavelength-multiplexed and transmitted through the optical transmission line (optical fiber) 3, and the optical demultiplexer 4 at the reception side transmits the respective wavelengths λ 1 to λ N. The optical transmission signal of 1 to λ N is demultiplexed and extracted. And each wavelength λ
The optical transmission signal of 1 to λ N is converted from an optical signal to an electric signal by the photoelectric converter 5 and desired signal processing is performed.
【０００３】このように、光伝送路３を用いて波長多重
光通信を行うことにより、大容量の情報通信が可能にな
る。As described above, by performing the wavelength division multiplexing optical communication using the optical transmission line 3, a large capacity information communication becomes possible.
【０００４】[0004]
【発明が解決しようとする課題】波長多重光通信を行う
場合、大容量の情報を送信する場合には、送信波長を細
分割して高密度送信を行うこととなるが、周知のよう
に、光信号を光伝送路３を用いて送信すると、波長分散
が生じる。この波長分散には、正の波長分散と負の波長
分散とがある。In the case of performing wavelength division multiplexing optical communication, when transmitting a large amount of information, the transmission wavelength is subdivided to perform high density transmission. As is well known, When an optical signal is transmitted using the optical transmission line 3, chromatic dispersion occurs. This wavelength dispersion includes positive wavelength dispersion and negative wavelength dispersion.
【０００５】正の波長分散は、送信波長が大きくなるに
つれ、光伝送路を通る光信号の屈折率が小さくなって、
伝送スピードが速くなり、このスピードアップ分に対応
して、光信号のパルス幅が進み方向に拡大する現象をい
う。負の波長分散は、これとは逆に、光送信信号の波長
が大きくなるにつれ、光伝送路を通る光信号の屈折率が
大きくなって、光伝送スピードが減少し、この光スピー
ドの減少分に応じて光信号のパルス幅が遅れ方向に拡大
する現象をいい、通常の光伝送用の光ファイバは、正の
波長分散を持っている。The positive chromatic dispersion is such that the refractive index of the optical signal passing through the optical transmission path becomes smaller as the transmission wavelength becomes larger.
This is a phenomenon in which the transmission speed becomes faster and the pulse width of the optical signal expands in the direction of advance, corresponding to this increase in speed. Negative chromatic dispersion, on the contrary, increases the refractive index of the optical signal passing through the optical transmission line as the wavelength of the optical transmission signal increases, decreasing the optical transmission speed. A pulse width of an optical signal expands in the delay direction in accordance with the above. An ordinary optical fiber for optical transmission has a positive chromatic dispersion.
【０００６】光伝送路３は、波長分散を持っているた
め、波長を細分割して高密度光通信を行うと、波長分散
のために、一方側の波長の光パルス信号と、他方側の波
長のパルス信号とが受信側で重なる場合が生じ、このよ
うな光信号の重なりが生じると、信号の分離が困難にな
り、通信不良を起こすという問題が生じる。Since the optical transmission line 3 has wavelength dispersion, when the wavelength is subdivided to perform high density optical communication, an optical pulse signal of one wavelength and the other side of the optical pulse signal are generated for wavelength dispersion. There may be a case where the pulse signals of the wavelengths overlap with each other on the receiving side, and when such an overlap of the optical signals occurs, it becomes difficult to separate the signals, which causes a problem of communication failure.
【０００７】図３は波長λ1 が1534nm、波長λ2 が1544
nm、波長λ3 が1546nm、波長λ4 が1554nmの各波長の光
送信信号を通常の分散シフトファイバ（波長1550nmで分
散値をほぼ零に設定した光ファイバ）を光伝送路３とし
て100 km送信した後の各波長の分散を示したものであ
る。この例ではλ1 では−100 ps／nm、λ2 では−30ps
／nm、λ3 では−16ps／nm、λ4 では＋40ps／nmであっ
た。FIG. 3 shows that the wavelength λ 1 is 1534 nm and the wavelength λ 2 is 1544.
nm, wavelength λ 3 is 1546 nm, and wavelength λ 4 is 1554 nm. Optical transmission signals of each wavelength are transmitted 100 km as optical transmission line 3 using an ordinary dispersion-shifted fiber (optical fiber with dispersion value set to almost zero at wavelength 1550 nm). It shows the dispersion of each wavelength after the process. In this example, λ 1 is -100 ps / nm, and λ 2 is -30 ps / nm.
/ Nm, the λ 3 -16ps / nm, was at λ 4 + 40ps / nm.
【０００８】この例から分かるように、送信側で同一パ
ルス形状の光信号を送ると、分散シフト波長の1550nmに
近い波長λ3 の受信波形は殆ど分散がなく、入力波形と
ほぼ同一の波形が得られているが、λ4 の受信波形は遅
れ方向に分散してパルス幅が拡大しており、λ2 の受信
波形は逆に進み方向に分散してパルス波形が広がってお
り、λ1 の受信波形はさらに進み方向の分散が増大し、
大きなパルス広がりの波形となっている。As can be seen from this example, when an optical signal of the same pulse shape is sent on the transmitting side, the received waveform of wavelength λ 3 close to the dispersion shift wavelength of 1550 nm has almost no dispersion, and a waveform almost identical to the input waveform is obtained. Although obtained, the reception waveform of lambda 4 is expanding the pulse width dispersed in the delay direction, the lambda 2 of the received waveform is spread pulse waveform dispersed in advance direction Conversely, lambda 1 of The received waveform has more variance in the forward direction,
The waveform has a large pulse spread.
【０００９】このλ1 の受信波形のように、波長分散が
大きくなると、通信の信頼性が損なわれるという問題が
生じ、また、λ1 〜λ4 の受信波形のように、波長分散
にばらつきが生じると、受信信号の信号処理がしずらく
なり、信号処理上のエラーが発生し易くなって、信号処
理の信頼性が損なわれるという問題が生じる。When the chromatic dispersion becomes large like the received waveform of λ 1 , there is a problem that the reliability of communication is impaired, and the chromatic dispersion varies like the received waveforms of λ 1 to λ 4. When it occurs, the signal processing of the received signal becomes difficult, and an error in the signal processing easily occurs, which causes a problem that the reliability of the signal processing is impaired.
【００１０】本発明は上記課題を解決するためになされ
たものであり、その目的は、各波長の光送信信号の波長
分散の増大を抑制し、受信側での各波長の大きな分散ば
らつきをなくし、通信の信頼性と、信号処理の信頼性を
共に高めることができる波長多重光通信システムを提供
することにある。The present invention has been made to solve the above problems, and an object thereof is to suppress an increase in chromatic dispersion of an optical transmission signal of each wavelength and to eliminate a large dispersion variation of each wavelength on the receiving side. The object of the present invention is to provide a wavelength division multiplexing optical communication system capable of improving both reliability of communication and reliability of signal processing.
【００１１】[0011]
【課題を解決するための手段】本発明は上記目的を達成
するために、次のように構成されている。すなわち、第
１の発明は、波長の異なる複数の光送信信号を光合波器
で合波した後、光伝送路を通して伝送し、受信側では光
伝送路によって伝送されて来る波長多重光信号を光分波
器で分波して各波長毎の信号として取り出す波長多重光
通信システムにおいて、前記光伝送路は正の波長分散ス
ロープを持つ光ファイバと負の波長分散スロープを持つ
光ファイバとを１本以上直列に接続して使用波長域での
光伝送路の波長分散スロープを零に近づけたことを特徴
として構成されている。In order to achieve the above object, the present invention is constructed as follows. That is, the first invention is that a plurality of optical transmission signals having different wavelengths are combined by an optical multiplexer, and then transmitted through an optical transmission line, and a wavelength-multiplexed optical signal transmitted by the optical transmission line is optically transmitted at the receiving side. In a wavelength division multiplexing optical communication system for demultiplexing by a demultiplexer and extracting as a signal for each wavelength, the optical transmission line includes one optical fiber having a positive chromatic dispersion slope and one optical fiber having a negative chromatic dispersion slope. The above is characterized in that they are connected in series and the chromatic dispersion slope of the optical transmission line in the used wavelength range is brought close to zero.
【００１２】また、前記光伝送路は正の波長分散値を持
つ光ファイバに負の波長分散値を持つ光ファイバを直列
に接続して使用波長域の所定波長の波長分散値を零に近
づけた後に、このファイバ接続体の分散スロープと逆の
分散スロープを持つ光ファイバを直列に接続して使用波
長域での光伝送路の波長分散値と波長分散スロープを共
に零に近づけたことも本発明の特徴とするところであ
る。In the optical transmission line, an optical fiber having a positive chromatic dispersion value and an optical fiber having a negative chromatic dispersion value are connected in series to bring the chromatic dispersion value of a predetermined wavelength in a used wavelength range close to zero. After that, both the chromatic dispersion value and the chromatic dispersion slope of the optical transmission line in the used wavelength range are brought close to zero by connecting in series optical fibers having a dispersion slope opposite to that of the fiber connection body of the present invention. It is a feature of.
【００１３】[0013]
【作用】上記構成の本発明において、送信側から受信側
に介設されている光伝送路は正の波長分散スロープを持
つ光ファイバと負の波長分散スロープを持つ光ファイバ
とが１本以上交互に直列接続されていることで、例え
ば、波長λ1 の光送信信号と、これよりも波長が徐々に
大きくなるλ2 ，λ3 ，λ4 の光送信信号を波長多重送
信したとき、例えば、正の波長分散スロープと正の波長
分散を持つ光ファイバを伝搬するときには、波長が大き
くなるにつれて進み方向の分散が大きくなるが、次の負
の波長分散スロープを持つ光ファイバを伝搬するときに
は、正の波長分散を持つものでは波長の大きい方の分散
変化が波長の小さい方の分散変化よりも小さくなり、負
の波長分散を持つ光ファイバでは波長が大きくなるにつ
れて遅れ方向の波長分散が大きくなる。In the present invention having the above-mentioned structure, the optical transmission line provided from the transmitting side to the receiving side has at least one optical fiber having a positive chromatic dispersion slope and at least one optical fiber having a negative chromatic dispersion slope. Are connected in series, for example, when the optical transmission signal of wavelength λ 1 and the optical transmission signals of λ 2 , λ 3 , and λ 4 whose wavelengths gradually increase are wavelength-multiplexed, for example, When propagating in an optical fiber with a positive chromatic dispersion slope and positive chromatic dispersion, the dispersion in the forward direction increases as the wavelength increases, but when propagating in the next optical fiber with a negative chromatic dispersion slope, The dispersion change of the larger wavelength is smaller than that of the smaller wavelength in the case of the optical fiber with negative chromatic dispersion, and the chromatic dispersion in the delay direction becomes larger as the wavelength becomes larger in the optical fiber with the negative chromatic dispersion. It becomes larger.
【００１４】このことで、正の波長分散スロープを持つ
光ファイバと負の波長分散スロープを持つ光ファイバと
を交互に通って受信側に達した各波長の光送信信号の波
長分散は大きなばらつきがなくほぼ同じに揃えられ、受
信側での各波長の波長分散の増大も防止される。As a result, the chromatic dispersion of the optical transmission signal of each wavelength which reaches the receiving side through the optical fiber having the positive chromatic dispersion slope and the optical fiber having the negative chromatic dispersion slope alternately has a large variation. The wavelengths are almost the same and are prevented from increasing on the receiving side.
【００１５】また、光伝送路の前半側に正の波長分散値
を持つ光ファイバに負の波長分散値を持つ光ファイバを
直列に接続して、使用波長域の所定波長の波長分散値を
零に近づけた後にこのファイバ接続体の分散スロープと
逆の分散スロープを持つ光ファイバを直列に接続した構
成のものにあっては、正の波長分散値と負の波長分散値
の光ファイバの接続体の終端側では、所定の波長、例え
ば、λ3 の波長の波長分散値はほぼ零になっており、そ
の他のλ1 ，λ2 ，λ4 の波長の波長分散値も小さな値
になっており、次の逆の分散スロープを持つ光ファイバ
を通ることによって、各波長λ1 〜λ4 の波長分散値が
ほぼ揃えられる結果、受信側の到達点では各波長の波長
分散が揃えられ、その値も小さなものとなる。Further, an optical fiber having a positive chromatic dispersion value is connected in series to an optical fiber having a positive chromatic dispersion value on the first half side of the optical transmission line so that the chromatic dispersion value of a predetermined wavelength in the used wavelength range is zero. In the case of a configuration in which optical fibers having a dispersion slope opposite to the dispersion slope of this fiber connection body are connected in series after being brought close to, the connection body of optical fibers with positive chromatic dispersion value and negative chromatic dispersion value On the terminal side of, the chromatic dispersion value of the predetermined wavelength, for example, the wavelength of λ 3 is almost zero, and the chromatic dispersion values of the other wavelengths of λ 1 , λ 2 , and λ 4 are also small values. , By passing through the optical fiber with the following inverse dispersion slope, the chromatic dispersion values of each wavelength λ 1 to λ 4 are almost equalized, and as a result, the chromatic dispersion of each wavelength is equalized at the arrival point on the receiving side, and the value is Will also be small.
【００１６】[0016]
【実施例】以下、本発明の実施例を図面に基づいて説明
する。なお、本実施例の説明において、従来例と同一の
名称部分には同一符号を付し、その重複説明は省略す
る。図１には、本発明の第１の実施例の波長多重光通信
システムが示されている。この実施例では、100 kmの光
伝送路３のうち、最初の75kmの光ファイバは一般に使用
されて分散シフトファイバ（分散シフト波長1550nmで波
長分散が＋0.12ps／nm／km、同じ波長1550nmで分散スロ
ープが＋0.07ps／nm2 ／km）６で構成し、残りの25kmの
光ファイバは、符号の異なる分散スロープを持つ光ファ
イバ（波長1550nmでの波長分散が＋0.08ps／nm／kmで、
同じ波長1550nmでの分散スロープが−0.21ps／nm2 ／k
m）７で構成したことである。この光ファイバ６，７は
光コネクタ８によって直列接続されている。Embodiments of the present invention will be described below with reference to the drawings. In the description of the present embodiment, the same names as those in the conventional example are designated by the same reference numerals, and the duplicate description thereof will be omitted. FIG. 1 shows a wavelength division multiplexing optical communication system according to a first embodiment of the present invention. In this embodiment, the first 75 km of the optical fiber of the 100 km optical transmission line 3 is generally used as a dispersion shift fiber (dispersion shift wavelength 1550 nm, chromatic dispersion +0.12 ps / nm / km, same wavelength 1550 nm). Dispersion slope is + 0.07ps / nm 2 / km) 6 and the remaining 25km of optical fiber has dispersion slope of different sign (wavelength dispersion at wavelength 1550nm is + 0.08ps / nm / km ,
Dispersion slope at the same wavelength of 1550nm is -0.21ps / nm 2 / k
m) 7. The optical fibers 6 and 7 are connected in series by an optical connector 8.
【００１７】なお、波長分散スロープとは、例えば、図
２に示すように、波長と分散の関係を示す特性（特性曲
線）を表したとき、その特性曲線の傾き、つまり、波長
の変化に対する波長分散値の変化の割合、換言すれば、
特性曲線の微分ｄσ／ｄλを意味する。σは波長分散
値、λは波長である。なお、図２のグラフは、単純シン
グルモード光ファイバの分散特性を一例として示してあ
る。Note that the chromatic dispersion slope is, for example, when a characteristic (characteristic curve) showing the relationship between wavelength and dispersion is represented as shown in FIG. 2, the slope of the characteristic curve, that is, the wavelength with respect to the change in wavelength. The rate of change of variance, in other words,
It means the derivative dσ / dλ of the characteristic curve. σ is a wavelength dispersion value, and λ is a wavelength. The graph of FIG. 2 shows the dispersion characteristics of a simple single mode optical fiber as an example.
【００１８】この実施例の光通信システムを利用して、
図３に示す従来例と同様な波長λ1〜λ4 の光送信信号
を送信側から受信側に向けて送信したところ、全ての波
長λ1 〜λ4 の受信信号の波長分散値は、＋11.00 ps／
nmとなり、各波長λ1 〜λ4の波長分散を一定に揃える
ことができ、また、その波長分散も小さな値とすること
ができた。これは、最初の光ファイバ６を通るときに
は、前記図３の従来例と同様に、光ファイバ６の終端側
では波長分散のばらつきが生じ、λ1 の波長はマイナス
方向の大きな値となり、λ2 の波長はマイナス方向に多
少分散が生じ、λ3 の波長はマイナス方向に極めて僅か
の波長分散が生じ、λ4 の波長はプラス方向に波長分散
が生じることとなるが、符号が逆の波長分散スロープを
持つ光ファイバ７を通ることによって、λ1 の波長の光
信号はプラス方向の比較的大きな波長分散の作用を受
け、波長λ2 の光信号はそれよりも小さなプラス方向の
分散の作用を受け、λ3 の波長の光信号は極めて小さい
がプラス方向の波長分散の作用を受け、λ4 の波長の光
信号はマイナス方向の波長分散の影響を受けることで、
光ファイバ７の終端側では、前記の如く、全ての波長λ
1 〜λ4 の光信号の波長分散が＋11.00 ps／nmという値
に揃えることができたものである。Utilizing the optical communication system of this embodiment,
When an optical transmission signal of wavelengths λ 1 to λ 4 similar to that of the conventional example shown in FIG. 3 is transmitted from the transmission side to the reception side, the chromatic dispersion values of the reception signals of all wavelengths λ 1 to λ 4 are +11. .00 ps /
Since the wavelength becomes nm, the wavelength dispersion of each wavelength λ 1 to λ 4 can be made uniform, and the wavelength dispersion can be set to a small value. This is because when passing through the first optical fiber 6, chromatic dispersion varies on the terminal side of the optical fiber 6 as in the conventional example of FIG. 3, and the wavelength of λ 1 becomes a large value in the negative direction, and λ 2 The λ 3 wavelength has some dispersion in the negative direction, the λ 3 wavelength has very little chromatic dispersion in the negative direction, and the λ 4 wavelength has chromatic dispersion in the positive direction. By passing through the optical fiber 7 having the slope, the optical signal of wavelength λ 1 is subjected to a relatively large chromatic dispersion effect in the positive direction, and the optical signal of wavelength λ 2 is subjected to a smaller positive dispersion effect. Therefore, the optical signal of wavelength λ 3 is extremely small, but is affected by chromatic dispersion in the positive direction, and the optical signal of wavelength λ 4 is affected by chromatic dispersion in the negative direction.
On the terminal side of the optical fiber 7, as described above, all wavelengths λ
The wavelength dispersion of the optical signal of 1 to λ 4 could be made uniform to the value of +11.00 ps / nm.
【００１９】従来の図３に示すシステムを用いた光送信
の場合には、前述した如く、λ1 の波長の光送信信号は
−100 ps／nm、同じくλ2 の波長の光信号は−30.00 ps
／nm、λ3 の光信号は−16.00 ps／nm、λ4 の波長の光
信号は＋40.00 ps／nmとなって、各波長λ1 〜λ4 の波
長分散が本実施例の場合よりも大きく、特に、λ1 の波
長の光信号は無視できない大きな波長分散が生じてお
り、かつ、各波長の波長分散が大きくばらついているの
に比べ、本実施例では、前記の如く、各波長λ1〜λ4
の波長分散を小さくでき、しかも、各波長λ1 〜λ4 の
波長分散のばらつきをなくしてほぼ一定に揃えることが
できるという優れた結果を得ることができ、これによ
り、光通信の信頼性を高めることができると共に、受信
側での各波長λ1 〜λ4 の信号処理の信頼性を高めるこ
とができた。In the case of the conventional optical transmission using the system shown in FIG. 3, as described above, the optical transmission signal of the wavelength λ 1 is -100 ps / nm and the optical signal of the wavelength λ 2 is -30.00. ps
/ Nm, λ 3 optical signal is -16.00 ps / nm, λ 4 wavelength optical signal is +40.00 ps / nm, and the chromatic dispersion of each wavelength λ 1 to λ 4 is larger than that of this embodiment. Is large, and in particular, an optical signal with a wavelength of λ 1 has a large chromatic dispersion that cannot be ignored, and the chromatic dispersion of each wavelength greatly varies. λ 1 to λ 4
It is possible to obtain the excellent result that the chromatic dispersion of can be made small, and furthermore, the dispersion of the chromatic dispersion of each wavelength λ 1 to λ 4 can be eliminated and the wavelengths can be made almost constant, thereby improving the reliability of optical communication. In addition to being able to increase the reliability, it was possible to improve the reliability of signal processing of each wavelength λ 1 to λ 4 on the receiving side.
【００２０】次に、本発明の第２の実施例を説明する。
この第２の実施例は、既存の1300nm零分散ファイバ伝送
路を転用して、1550nmの波長多重高速通信を行うように
構成したものである。この第２の実施例では、送信側か
ら受信側にかけての光伝送路３を、通常の1300nm零分散
ファイバで100 kmの光伝送路を形成し、その後に、波長
1550nm付近で分散をほぼ零に合わせた負の大きな分散を
持つ負分散光ファイバ（分散値＝−80ps／nm／km）を21
km直列接続し、その後に、前記既存の1300nm零分散ファ
イバと負分散光ファイバとのファイバ直列結合体の分散
スロープと符号の異なる分散スロープを持つ終端光ファ
イバ（波長1550nmで分散が＋0.08ps／nm／km、同じく波
長1550nmで分散スロープが−0.21ps／nm2 ／km）30kmを
接続して波長多重光通信システムを形成している。Next, a second embodiment of the present invention will be described.
In the second embodiment, the existing 1300 nm zero-dispersion fiber transmission line is diverted to perform wavelength-multiplexed high-speed communication of 1550 nm. In the second embodiment, the optical transmission line 3 from the transmitting side to the receiving side is formed with a normal 1300 nm zero dispersion fiber to form a 100 km optical transmission line, and then the wavelength is
A negative dispersion optical fiber (dispersion value = -80ps / nm / km) with a large negative dispersion that matched the dispersion near 0 at 1550nm was used.
km series connection, and after that, a termination optical fiber with a dispersion slope whose sign is different from the dispersion slope of the fiber series combination of the existing 1300 nm zero-dispersion fiber and negative dispersion optical fiber (dispersion of +0.08 ps / wavelength at 1550 nm / nm / km, the same wavelength of 1550 nm and dispersion slope of −0.21 ps / nm 2 / km) 30 km are connected to form a wavelength division multiplexing optical communication system.
【００２１】この第２の実施例の光通信システムを用い
て前記第１の実施例と同じ波長λ1〜λ4 の光信号を送
信する実験を行った。An experiment was carried out using the optical communication system of the second embodiment to transmit optical signals of the same wavelengths λ 1 to λ 4 as in the first embodiment.
【００２２】この光通信システムにおいて、通常の1300
nm零分散ファイバは波長1550nmで約17ps／nm／kmの分散
を持つので、100 km通過したときの終端での分散が1700
ps／nmと大きな値となり、この状態で高速通信を行うと
大きな弊害を生じる。本実施例では、この1300nm零分散
ファイバの次に負の大きな分散を持つ負分散光ファイバ
を接続し、波長1550nm付近で分散をほぼ零に合わせたこ
とで、波長1550nmにおける伝送路の分散は＋10ps／nm、
分散スロープは＋８ps／nm2 となり、したがって、この
負分散光ファイバを通過した各波長λ1 〜λ4 の分散
は、波長λ1 で−118 、波長λ2 で−38、波長λ3 で−
22、波長λ4 で＋42ps／nmと小さくなっているが、波長
分散の大きなλ1 の波長（1534nmの波長）等では、信号
波形に歪が生じており、通信の信頼性の上ではまだ充分
な状態とはなっていなかった。In this optical communication system, a normal 1300
nm zero-dispersion fiber has a dispersion of about 17 ps / nm / km at a wavelength of 1550 nm, so the dispersion at the end when passing 100 km is 1700.
The value is as large as ps / nm, and high-speed communication in this state causes a serious problem. In this embodiment, a negative dispersion optical fiber having a large negative negative dispersion is connected next to the 1300 nm zero dispersion fiber, and the dispersion is adjusted to almost zero near the wavelength of 1550 nm, so that the dispersion of the transmission line at the wavelength of 1550 nm is +10 ps. / Nm,
The dispersion slope is +8 ps / nm 2 , and therefore the dispersion of each wavelength λ 1 to λ 4 that has passed through this negative dispersion optical fiber is −118 at wavelength λ 1 , −38 at wavelength λ 2 , and − at wavelength λ 3 .
22. It is as small as +42 ps / nm at wavelength λ 4 , but the signal waveform is distorted at wavelength λ 1 (wavelength of 1534 nm) with large wavelength dispersion, which is still sufficient for communication reliability. It was not in such a state.
【００２３】しかし、次に、符号の異なる分散スロープ
を持つ前記終端光ファイバを通したことで、その終端の
受信側では、λ1 の波長の光信号は−14.8、λ2 の光信
号は−2.2 、波長λ3 の光信号は−5.6 、波長λ4 の光
信号は＋21.4ps／nmと各波長λ1 〜λ4 の分散を大幅に
低減することができた。この光通信システムを用いて波
長多重光通信の実験を繰り返し行ったところ、どの波長
でも、信号波形が変形せず、受信不良が生じるというこ
とがなく、信頼性の高い波長多重光通信が可能となっ
た。また、各波長λ1 〜λ4 の分散のばらつきを小さく
揃えることができたことで、受信信号の信号処理がし易
くなり、その信号処理の上でもエラーが発生するという
ことがなく、その信頼性も高めることができた。However, next, by passing through the terminal optical fibers having dispersion slopes of different signs, the optical signal of wavelength λ 1 is −14.8 and the optical signal of λ 2 is − 2.2, the optical signal of wavelength λ 3 was −5.6, and the optical signal of wavelength λ 4 was +21.4 ps / nm, which was able to greatly reduce the dispersion of each wavelength λ 1 to λ 4 . Repeated experiments of wavelength-division-multiplexed optical communication using this optical communication system showed that the signal waveform was not deformed at any wavelength, and reception failure did not occur, enabling reliable wavelength-division-multiplexed optical communication. became. Further, since the dispersion of the dispersion of each wavelength λ 1 to λ 4 can be made small, the signal processing of the received signal can be easily performed, and no error occurs in the signal processing. I was able to improve the sex.
【００２４】ところで、1300nm用伝送路の分散を補償す
るために挿入する分散補償ファイバにおいて、負の大き
な分散を持ち、同時に負のスロープを持たせることは不
可能ではない。もし、このファイバを用いれば、理論上
は１本のファイバを挿入するだけで波長多重にも使用で
きる分散の波長平坦性を実現することができる。しか
し、製造の容易な単純なステップ形プロファイルでこの
様な分散特性は実現するのは困難で、したがって、複雑
なファイバ構造が必要になり、加えて僅かなコア径等、
構造パラメーターの違いで分散スロープが大きく変化す
るため、実際に安定して製造することは困難である。ま
た、ファイバ構造が複雑なために伝送損失も格段に大き
くなり、システム構成した場合に光アンプを余分に挿入
する必要が生ずる等、その点でも不利に働く。By the way, it is not impossible to have a large negative dispersion and a negative slope at the same time in the dispersion compensating fiber inserted for compensating the dispersion of the 1300 nm transmission line. If this fiber is used, theoretically, it is possible to realize the wavelength flatness of dispersion that can be used for wavelength multiplexing simply by inserting one fiber. However, it is difficult to realize such dispersion characteristics with a simple step profile that is easy to manufacture, and thus requires a complicated fiber structure, and in addition, a small core diameter, etc.
Since the dispersion slope changes greatly due to the difference in the structural parameters, it is difficult to actually manufacture it stably. Further, since the fiber structure is complicated, the transmission loss is significantly increased, and it becomes necessary to additionally insert an optical amplifier when the system is configured, which is also disadvantageous.
【００２５】例えば、分散が−80ps／nm／kmの分散補償
ファイバを用いたとき、1300nm用伝送路を補償するのに
は伝送路の0.21倍の長さを接続すればよいが、同時に波
長平坦性を求めるなら分散スロープは−0.27ps／nm2 ／
kmにする必要がある。理論設計上は実現可能であるが、
実際はコアからの光の漏れが生じる等の影響があって、
高分散と同時に実現できる分散スロープとしては−0.20
ps／nm2 ／kmが技術的には限界であり、また、曲げたと
きにロスが増加し易い構造のためケーブル化や伝送機器
内蔵用パッケージ化で問題が生じる。For example, when a dispersion compensating fiber having a dispersion of −80 ps / nm / km is used, a length of 0.21 times the length of the transmission line may be connected to compensate for the 1300 nm transmission line, but at the same time the wavelength flat If the property is required, the dispersion slope is −0.27ps / nm 2 /
Need to be km. It is feasible in theoretical design,
Actually, there is an effect such as light leakage from the core,
-0.20 as a dispersion slope that can be realized at the same time as high dispersion
Technically, ps / nm 2 / km is the limit, and since the structure tends to increase the loss when bent, problems will arise in making cables and packaging for built-in transmission equipment.
【００２６】さらに、短い長さの分散補償ファイバで伝
送路の分散を補償しようとする場合、より大きな負の高
分散（−100 ps／nm／km以下）の実現が必要になるが、
このような構造において大きな負の分散スロープを得る
ことは一層困難である。Furthermore, in order to compensate for the dispersion of the transmission line with a dispersion compensating fiber having a short length, it is necessary to realize a larger negative high dispersion (-100 ps / nm / km or less).
It is more difficult to obtain a large negative dispersion slope in such a structure.
【００２７】実施例では、負の高分散を持つファイバ
と、負の分散スロープを持つファイバを独立に作製する
ことができるため、単純なファイバ構造で必要な分散特
性を容易に実現できる。したがって、必要な分散特性を
持つファイバが経済的に作製できる。また、各々のファ
イバの伝送損失も小さく抑えることが容易である。加え
て、伝送路に挿入したときに、最後に分散スロープの分
を調整するため、格段に簡単で広い波長域で分散を零に
近く調整でき、システム構成が簡単になる。In the embodiment, since a fiber having a high negative dispersion and a fiber having a negative dispersion slope can be manufactured independently, it is possible to easily realize the required dispersion characteristics with a simple fiber structure. Therefore, a fiber having the required dispersion characteristics can be manufactured economically. It is also easy to keep the transmission loss of each fiber small. In addition, since the amount of the dispersion slope is adjusted at the end when it is inserted in the transmission line, the dispersion can be adjusted extremely easily and the dispersion can be adjusted close to zero in a wide wavelength range, and the system configuration can be simplified.
【００２８】なお、本発明は上記各実施例に限定される
ことはなく、様々な実施の態様を採り得る。例えば、上
記各実施例では、λ1 〜λ4 の光送信信号の多重光通信
の場合で説明したが、実際には、より多くの波長λ1 〜
λN の光送信信号の多重光通信が可能である。このよう
に多数の波長の光信号を多重通信しても、前記の如く、
本実施例では、符号の異なる波長分散スロープを持つ光
ファイバを１本以上直列に接続して光伝送路が形成され
るものであるから、広い波長域で分散を零に近づけて揃
えることができることとなる。It should be noted that the present invention is not limited to the above embodiments, but can take various embodiments. For example, in each of the above-described embodiments, the description has been made in the case of the multiplex optical communication of the optical transmission signals of λ 1 to λ 4 , but in reality, more wavelengths λ 1 to
Multiplex optical communication of optical transmission signals of λ N is possible. Even when multiplex communication of optical signals of many wavelengths is performed as described above,
In the present embodiment, one or more optical fibers having different wavelength chromatic dispersion slopes are connected in series to form an optical transmission line, so that the dispersion can be brought close to zero and aligned in a wide wavelength range. Becomes
【００２９】[0029]
【発明の効果】本発明は、送信側から受信側にかけての
光伝送路を、正の波長分散スロープを持つ光ファイバ
と、負の波長分散スロープを持つ光ファイバとを１本以
上直列に接続して構成したものであるから、送信側から
送信した広い波長域での複数の波長分割多重の光送信信
号を、受信側で、各波長の分散を小さくし、かつ、各波
長の分散のばらつきを小さくして揃えることができ、こ
れにより、例えば、100 km以上の長距離においても、波
長多重高速通信の信頼性を高めることができると共に、
受信側での信号処理の容易化と、その信号処理の信頼性
を高めることができる。According to the present invention, one or more optical fibers having a positive chromatic dispersion slope and one or more optical fibers having a negative chromatic dispersion slope are connected in series in the optical transmission line from the transmitting side to the receiving side. The wavelength-division-multiplexed optical transmission signal in a wide wavelength range transmitted from the transmitting side reduces the dispersion of each wavelength on the receiving side, and the dispersion of the dispersion of each wavelength is It can be made smaller and aligned, which makes it possible to increase the reliability of wavelength-multiplexed high-speed communication even over a long distance of 100 km or more, for example.
The signal processing on the receiving side can be facilitated and the reliability of the signal processing can be improved.
【００３０】また、正の波長分散値を持つ光ファイバに
負の波長分散値を持つ光ファイバを直列に接続して使用
波長域の所定波長の波長分散値を零に近づけた後に、逆
の分散スロープを持つ光ファイバを直列に接続した光伝
送路にあっては、各波長の光送信信号を受信側で各波長
の分散のばらつきを小さくして揃えることができると共
に、各波長の分散値をほぼ零に近づけることができ、光
多重通信の信頼性と信号処理の信頼性をより一層高める
ことができる。さらに、本発明では、負の高分散を持つ
ファイバと、負の分散スロープを持つファイバを独立に
作製することができるため、単純なファイバ構造で必要
な分散特性を容易に実現できる。したがって、必要な分
散特性を持つファイバが経済的に作製できる。また、各
々のファイバの伝送損失も小さく抑えることが容易であ
る。加えて、伝送路に挿入したときに、最後に分散スロ
ープの分を調整するため、格段に簡単で広い波長域で分
散を零に近く調整でき、システム構成が簡単になる。Further, an optical fiber having a negative chromatic dispersion value is connected in series to an optical fiber having a positive chromatic dispersion value to bring the chromatic dispersion value of a predetermined wavelength in the used wavelength range close to zero, and then the reverse dispersion is obtained. In an optical transmission line in which optical fibers with slopes are connected in series, the optical transmission signals of each wavelength can be made uniform by reducing the dispersion of the dispersion of each wavelength on the receiving side, and the dispersion value of each wavelength can be adjusted. It can be brought close to zero, and the reliability of optical multiplex communication and the reliability of signal processing can be further improved. Further, according to the present invention, since a fiber having a high negative dispersion and a fiber having a negative dispersion slope can be manufactured independently, it is possible to easily realize a required dispersion characteristic with a simple fiber structure. Therefore, a fiber having the required dispersion characteristics can be manufactured economically. It is also easy to keep the transmission loss of each fiber small. In addition, since the amount of the dispersion slope is adjusted at the end when it is inserted in the transmission line, the dispersion can be adjusted extremely easily and the dispersion can be adjusted close to zero in a wide wavelength range, and the system configuration can be simplified.
【図１】本発明に係る波長多重光通信システムの一実施
例を示すシステム構成図である。FIG. 1 is a system configuration diagram showing an embodiment of a wavelength division multiplexing optical communication system according to the present invention.
【図２】波長分散スロープを説明するための波長分散特
性の一例を示すグラフである。FIG. 2 is a graph showing an example of chromatic dispersion characteristics for explaining a chromatic dispersion slope.
【図３】光伝送路に通常の分散シフトファイバを用いた
波長多重光通信システムの説明図である。FIG. 3 is an explanatory diagram of a wavelength division multiplexing optical communication system using an ordinary dispersion shift fiber in an optical transmission line.
【図４】波長多重光通信システムの一般的な構成例を示
す説明図である。FIG. 4 is an explanatory diagram showing a general configuration example of a wavelength division multiplexing optical communication system.
２ 光合波器 ３ 光伝送路 ４ 光分波器 ６，７ 光ファイバ 2 Optical multiplexer 3 Optical transmission line 4 Optical demultiplexer 6,7 Optical fiber
───────────────────────────────────────────────────── フロントページの続き (51)Int.Cl.6 識別記号 庁内整理番号 ＦＩ 技術表示箇所 Ｈ０４Ｂ 10/18 ─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. 6 Identification code Internal reference number FI technical display location H04B 10/18
Claims (2)
器で合波した後、光伝送路を通して伝送し、受信側では
光伝送路によって伝送されて来る波長多重光信号を光分
波器で分波して各波長毎の信号として取り出す波長多重
光通信システムにおいて、前記光伝送路は正の波長分散
スロープを持つ光ファイバと負の波長分散スロープを持
つ光ファイバとを１本以上直列に接続して使用波長域で
の光伝送路の波長分散スロープを零に近づけたことを特
徴とする波長多重光通信システム。1. An optical demultiplexer that combines a plurality of optical transmission signals having different wavelengths by an optical multiplexer, transmits the optical transmission signals through an optical transmission line, and receives the wavelength-division multiplexed optical signal transmitted by the optical transmission line on the receiving side. In the wavelength-division-multiplexed optical communication system for demultiplexing with each wavelength and extracting as a signal for each wavelength, the optical transmission line has one or more optical fibers having a positive chromatic dispersion slope and an optical fiber having a negative chromatic dispersion slope in series. A wavelength division multiplexing optical communication system characterized in that the wavelength dispersion slope of an optical transmission line in a used wavelength region is connected to be close to zero.
イバに負の波長分散値を持つ光ファイバを直列に接続し
て使用波長域の所定波長の波長分散値を零に近づけた後
に、このファイバ接続体の分散スロープと逆の分散スロ
ープを持つ光ファイバを直列に接続して使用波長域での
光伝送路の波長分散値と波長分散スロープを共に零に近
づけた請求項１記載の波長多重光通信システム。2. An optical transmission line, wherein an optical fiber having a positive chromatic dispersion value and an optical fiber having a negative chromatic dispersion value are connected in series to make the chromatic dispersion value of a predetermined wavelength in a used wavelength range close to zero. The chromatic dispersion value and the chromatic dispersion slope of the optical transmission line in the used wavelength range are both close to zero by connecting in series optical fibers having a dispersion slope opposite to that of the fiber connection body. WDM optical communication system.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6244690A JPH0884135A (en) | 1994-09-13 | 1994-09-13 | Wavelength multiplexed optical communication system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP6244690A JPH0884135A (en) | 1994-09-13 | 1994-09-13 | Wavelength multiplexed optical communication system |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH0884135A true JPH0884135A (en) | 1996-03-26 |
Family
ID=17122494
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP6244690A Pending JPH0884135A (en) | 1994-09-13 | 1994-09-13 | Wavelength multiplexed optical communication system |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH0884135A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP2000028841A (en) * | 1998-07-07 | 2000-01-28 | Furukawa Electric Co Ltd:The | Optical fiber type optical parts |
| US6157754A (en) * | 1997-05-09 | 2000-12-05 | Sumitomo Electric Industries, Ltd. | Optical transmission line |
| US6160931A (en) * | 1997-10-28 | 2000-12-12 | Matsushita Electric Industrial Co., Ltd. | Wavelength-multiplexing optical transmission system provided with wavelength selectors |
-
1994
- 1994-09-13 JP JP6244690A patent/JPH0884135A/en active Pending
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US6157754A (en) * | 1997-05-09 | 2000-12-05 | Sumitomo Electric Industries, Ltd. | Optical transmission line |
| US6160931A (en) * | 1997-10-28 | 2000-12-12 | Matsushita Electric Industrial Co., Ltd. | Wavelength-multiplexing optical transmission system provided with wavelength selectors |
| JP2000028841A (en) * | 1998-07-07 | 2000-01-28 | Furukawa Electric Co Ltd:The | Optical fiber type optical parts |
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