JPH06132895A - Optical power change compensating circuit and optical transmitter - Google Patents
Optical power change compensating circuit and optical transmitterInfo
- Publication number
- JPH06132895A JPH06132895A JP4281362A JP28136292A JPH06132895A JP H06132895 A JPH06132895 A JP H06132895A JP 4281362 A JP4281362 A JP 4281362A JP 28136292 A JP28136292 A JP 28136292A JP H06132895 A JPH06132895 A JP H06132895A
- Authority
- JP
- Japan
- Prior art keywords
- signal
- optical
- output
- wavelength
- main
- 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
- 230000003287 optical effect Effects 0.000 title claims abstract description 267
- 239000013307 optical fiber Substances 0.000 claims abstract description 34
- 230000005540 biological transmission Effects 0.000 claims abstract description 33
- 239000004065 semiconductor Substances 0.000 claims description 9
- 230000003321 amplification Effects 0.000 claims description 3
- 238000003199 nucleic acid amplification method Methods 0.000 claims description 3
- 230000000295 complement effect Effects 0.000 claims 2
- 230000002194 synthesizing effect Effects 0.000 abstract 1
- 230000000694 effects Effects 0.000 description 10
- 230000006866 deterioration Effects 0.000 description 9
- 239000006185 dispersion Substances 0.000 description 3
- 230000001902 propagating effect Effects 0.000 description 2
- 238000001228 spectrum Methods 0.000 description 2
- 238000010521 absorption reaction Methods 0.000 description 1
- 238000001514 detection method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 238000012544 monitoring process Methods 0.000 description 1
- 230000010363 phase shift Effects 0.000 description 1
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
- H04B10/25—Arrangements specific to fibre transmission
- H04B10/2507—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion
- H04B10/2543—Arrangements specific to fibre transmission for the reduction or elimination of distortion or dispersion due to fibre non-linearities, e.g. Kerr effect
- H04B10/2557—Cross-phase modulation [XPM]
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04J—MULTIPLEX COMMUNICATION
- H04J14/00—Optical multiplex systems
- H04J14/02—Wavelength-division multiplex systems
- H04J14/0221—Power control, e.g. to keep the total optical power constant
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Electromagnetism (AREA)
- Lasers (AREA)
- Optical Communication System (AREA)
Abstract
Description
【産業上の利用分野】本発明は、波長多重を用いた光フ
ァイバ伝送装置に係わり、特に、光ファイバ中の非線形
光学現象の一つであるクロス位相変調に起因する伝送特
性劣化の低減に有効な光伝送装置に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber transmission device using wavelength division multiplexing, and is particularly effective in reducing transmission characteristic deterioration due to cross phase modulation which is one of nonlinear optical phenomena in an optical fiber. Optical transmission device.
【従来の技術】クロス位相変調に起因する伝送特性劣化
という問題は、例えば、文献 G. Agrawal著, “Nonline
ar Fiber Optics,”にて指摘されているが、解決方法に
ついての提案は未だない。2. Description of the Related Art The problem of deterioration of transmission characteristics due to cross-phase modulation is described, for example, in the article by G. Agrawal, "Nonline.
ar Fiber Optics, ”pointed out, but there is no suggestion of a solution yet.
【発明が解決しようとする課題】本発明の目的は、クロ
ス位相変調に起因する伝送特性劣化という問題を解決す
ることにある。SUMMARY OF THE INVENTION An object of the present invention is to solve the problem of deterioration of transmission characteristics due to cross phase modulation.
【課題を解決するための手段】クロス位相変調とは、波
長多重光ファイバ伝送において、ある波長の光信号が、
波長多重光信号（主信号）の光パワーにほぼ比例した位
相変調を受ける現象である。本発明では、光送信装置に
おいて主信号の光パワー変化を検出し、該変化を補償す
る補償光信号を発生し、該補償光信号を主信号に合波
し、光ファイバに入力する光パワーを一定に保つことに
より、光パワー変動に起因するクロス位相変調を低減す
るものである。Cross-phase modulation means that in a wavelength-multiplexed optical fiber transmission, an optical signal of a certain wavelength is
This is a phenomenon in which the phase modulation is substantially proportional to the optical power of the wavelength-multiplexed optical signal (main signal). In the present invention, a change in the optical power of the main signal is detected in the optical transmitter, a compensation optical signal for compensating for the change is generated, the compensated optical signal is multiplexed with the main signal, and the optical power input to the optical fiber is adjusted. By keeping it constant, cross phase modulation due to optical power fluctuation is reduced.
【作用】Ｎ波長の波長多重光ファイバ伝送システムを考
える。各波長の光パワーはＰ1〜ＰN とし、最大パワー
ＰMax および最小パワーＰMin はすべて等しいものとす
る。この時、クロス位相変調によりｊ番目の波長（以
下、チャネルｊと呼ぶ、ｊ＝１〜Ｎ）に生ずる位相変化
φj は、前記文献の第７章にて導出されており、次式に
て表される。Consider a wavelength multiplexing optical fiber transmission system of N wavelengths. The optical power of each wavelength is P 1 to P N , and the maximum power P Max and the minimum power P Min are all equal. At this time, the phase change φ j that occurs at the j-th wavelength (hereinafter, referred to as channel j, j = 1 to N) due to the cross phase modulation is derived in Chapter 7 of the above-mentioned document, and expressed.
【数１】 上式において、γは光ファイバの非線形定数であり、Ｌ
effは光ファイバの有効長である。上式によれば、位相
変化はチャネルｊ自身の光パワーＰjと他のチャネルの
光パワーの２倍の和２ΣＰn （但し、n＝１〜Ｎ、n≠
ｊ）に比例して時間的に変化する。位相変化量の最大値
は、各波長の光信号が同時に最大パワーとなった場合の
位相変化と最小パワーとなった場合の位相変化の差であ
り、次式となる。[Equation 1] In the above equation, γ is the nonlinear constant of the optical fiber, and L
eff is the effective length of the optical fiber. According to the above equation, the phase change is the sum of the optical power P j of the channel j itself and the optical power of the other channels 2 ΣP n (where n = 1 to N, n ≠
It changes with time in proportion to j). The maximum value of the amount of phase change is the difference between the phase change when the optical signal of each wavelength has the maximum power at the same time and the phase change when the optical signal has the minimum power, and is given by the following equation.
【数２】 Δφj＝φj（最大値）−φj（最小値） ＝γＬeff［ＰMax＋２（Ｎ−１）ＰMax］ −γＬeff［ＰMin＋２（Ｎ−１）ＰMin］ ＝γＬeff（２Ｎ−１）（ＰMax−ＰMin） （２） ここで、全チャネルの光パワーの和をＰSUM （＝ΣＰ
n 、ｎ＝１〜Ｎ）で表し、補償光信号の光パワーＰC を
次式のように設定する。## EQU2 ## Δφ j = φ j (maximum value) -φ j (minimum value) = γL eff [P Max +2 (N-1) P Max ] -γL eff [P Min +2 (N-1) P Min ] = ΓL eff (2N−1) (P Max −P Min ) (2) Here, the sum of the optical powers of all channels is P SUM (= ΣP
n , n = 1 to N), and the optical power P C of the compensation optical signal is set as in the following equation.
【数３】 ＰC＝ＮＰMax−ＰSUM （３） 数（３）の補償光信号を波長多重光信号に合波（波長多
重）すると、クロス位相変調によりチャネルｊの位相に
生ずる変化φj'は次式となる。Equation 3] P C = NP Max -P SUM ( 3) Number (3) compensating optical signals multiplexed in wavelength-multiplexed optical signal (wavelength multiplexed), the change caused by the cross-phase modulation of the channel j phase phi j 'Is the following formula.
【数４】 数（４）によると、位相変化φj'はＮＰMax およびＰj
に依存するが、ＮＰMaxは定数であり、従って、ＮＰ
Max に起因する位相変化（数（４）第１項）も定数とな
り、時間的に変化しない。一方、Ｐj は時間的に変化す
るため、Ｐj に起因する位相変化（数（４）第２項）も
時間的に変化する。従って、伝送特性に影響を及ぼす位
相変化は数（４）における第２項のγＬeffＰjのみであ
り、位相変化量の最大値は次式となる。[Equation 4] According to the equation (4), the phase change φ j ′ is NP Max and P j
, But NP Max is a constant and therefore NP Max
The phase change caused by Max (the first term of the equation (4)) also becomes a constant and does not change with time. On the other hand, since P j changes with time, the phase change (the second term of the equation (4)) due to P j also changes with time. Therefore, the phase change that affects the transmission characteristics is only γL eff P j of the second term in the equation (4), and the maximum value of the phase change amount is given by the following equation.
【数５】 Δφj'＝φj'（最大値）−φj'（最小値） ＝γＬeffＰMax−γＬeffＰMin ＝γＬeff（ＰMax−ＰMin） （５） 以上をまとめると、補償光信号を用いない場合と用いた
場合それぞれの位相変化量の最大値は数（２）および数
（５）にて与えられる。位相偏移量の最大値が小さけれ
ば、伝送特性がクロス位相変調により受ける劣化も小さ
い。そこで、数（２）に対する数（５）の比を求めると
次式を得る。Equation 5] Δφ j '= φ j' (maximum value) -φ j '(minimum value) = γL eff P Max -γL eff P Min = ΓL eff (P Max −P Min ) (5) Summarizing the above, the maximum value of the phase change amount when the compensation light signal is not used and when it is used is given by Equation (2) and Equation (5). To be When the maximum value of the phase shift amount is small, the deterioration of the transmission characteristic due to the cross phase modulation is small. Then, when the ratio of the number (5) to the number (2) is obtained, the following equation is obtained.
【数６】 数（６）より、補償光信号を合波することにより、位相
変化量は１／（２Ｎ−１）に低減されるていることがわ
かる。即ち、補償光信号を用いた本発明により、クロス
位相変調を低減でき、伝送特性劣化を低減できるという
効果を得る。[Equation 6] From equation (6), it can be seen that the amount of phase change is reduced to 1 / (2N-1) by multiplexing the compensation optical signals. That is, according to the present invention using the compensated optical signal, it is possible to reduce the cross phase modulation and reduce the deterioration of the transmission characteristics.
【実施例】図１には、本発明を実現するための光送信装
置の第１実施例を示す。データ１〜データＮはそれぞれ
波長が異なるレーザ（送信用レーザ）にて光信号に変換
した後に合波する。合波器は、例えば光カプラやグレー
ティングを用いた光フィルタ等にて実現できる。合波器
出力として得られる波長多重光信号（主信号）は光アン
プにて増幅される。該光送信装置から出力した主信号
は、光パワー変化補償回路２−１に入力する。該補償回
路では、まず主信号を分岐器により２分岐する。分岐に
より得られた第１の主信号の光パワーをＰSUM とし（最
大値はＮＰMax）、第２の主信号の光パワーをｋＰSUM
とする（最大値はｋＮＰMax 、ｋは分岐器により決まる
定数）。第１の主信号の光パワーの波形例を図２（ａ）
に示す。第２の主信号は受光器に入力する。該受光器は
光パワーに比例する電圧（あるいは電流）信号Ｖｐ（＝
ｋＫＰSUM 、Ｋは受光器により決まる定数）を出力す
る。減算器では基準信号Ｖｏから信号Ｖｐを減算し、そ
の差信号ΔＶ（＝Ｖｏ−Ｖｐ）を出力する。Ｖｏの値と
しては、例えば、信号Ｖｐの最大値ｋＫＮＰMax に設定
すればよい。このとき、差信号ΔＶはｋＫ（ＮＰMax −
ＰSUM）に等しくなる。加算器では、差信号ΔＶにバイ
アス信号Ｖｂを加算し、信号（Ｖｂ＋ΔＶ）をドライブ
回路に入力する。ドライブ回路は信号（Ｖｂ＋ΔＶ）に
比例する電流で補償用レーザを駆動する。例えば、信号
Ｖｂをレーザの閾値電流に対応する値に設定すれば、レ
ーザは差信号ΔＶに比例する光パワーｋＫＬ（ＮＰMax
−ＰＳＵＭ）の光信号を出力する（Ｌはレーザにより決
まる定数）。ここで補償用レーザの波長は送信用レーザ
とは異なる値に設定するものとする。補償用レーザから
の光信号は光アンプにて増幅し、光パワーｇｋＫＬ（Ｎ
ＰＭａｘ −ＰSUM）の補償光信号として出力する（ｇ
は光アンプの利得）。ここで、定数の積ｇｋＫＬが１に
等しくなるように各定数ｇ、ｋ、Ｋ、Ｌを設定すれば、
該光アンプから出力される補償光信号のパワーは数
（３）のＰCに等しくなる（図２（ｂ）に波形例を示
す）。従って、この補償光信号を上記第１の主信号に合
波すると、図２（ｃ）に示すような光パワー一定の光信
号を得ることができ、その結果、位相変化量を数（６）
に示すように１／（２Ｎ−１）に低減することができ
る。即ち、本実施例によりクロス位相変調を低減でき、
伝送特性劣化を低減できるという効果を得る。なお、１
−１は本実施例の光送信装置全体を表している。なお、
図３には主信号および補償光信号のスペクトル配置例を
示す。同図に示すように、補償光信号を主信号（チャネ
ル１〜チャネルＮ）より短波長側に配置しても（同図
（ａ））、長波長側に配置しても（同図（ｂ））、ま
た、主信号を構成するチャネルとチャネルの間に配置し
ても（同図（ｃ）ではチャネルｎとチャネルｎ＋１の
間、但し、１≦ｎ≦Ｎ）、上記効果を得ることができ
る。図４には、本発明を実現するための光送信装置の第
２実施例を示す。本実施例と第１実施例との相違は、主
信号の光パワーに生ずる変化を、電気信号（データ１〜
データＮ）の検出により間接的に求めるものである。図
４に示すように、各データ信号はレーザを変調する前に
２分岐され、一方はレーザの変調に用い、他方は光パワ
ー変化補償回路に入力する。各レーザからの出力光信号
は、第１実施例と同様に合波器にて多重され、光アンプ
にて増幅された後に主信号として出力される（波形は図
２（ａ）と同じ）。一方、該光パワー変化補償回路に入
力したデータ１〜データＮは、加算器にて加算された後
に、減算器に入力し、基準値（例えばＮ）との差を検出
する。その後段の加算器では該減算器の出力にバイアス
値を加算して、ドライブ回路に入力する。該ドライブ回
路は補償用レーザを駆動し、補償光信号（波形図２
（ｂ））を出力する。最後に上記主信号と上記補償光信
号とは合波器にて合波されて、光ファイバへと送出され
る。このとき、該補償光信号の波形は、主信号の変化を
補償する波形となっているので、主信号と補償光信号の
和は一定値となる。即ち、図２（ｃ）の波形の光信号が
光ファイバに送出されるので、数（６）にて示されるよ
うに、クロス位相変調に起因する位相変化を１／（２Ｎ
−１）に抑圧することができるという効果を得る。な
お、図中の１−２は本実施例の光送信装置全体を表して
いる。なお、本実施例では、各データ信号間のビット同
期がとれている場合には、上記分岐データの加算はさら
に容易となる。なお、上記第１及び第２実施例では、レ
ーザの直接変調により光信号への変調（光強度変調、光
振幅変調、光周波数変調等）を実現しているが、光の変
調器を用いて光信号への変調を実現してもよい。変調器
は、例えば、電界吸収型やマッハツェンダ型の変調器に
て実現することができる。変調器はレーザから出力する
パワー一定の光を入力とし、該入力光に対して、変調器
に印加される電気信号に応じた変調（光強度変調、光振
幅変調、光位相変調等）を施して出力する。上記変調器
を用いると、光強度変調（あるいは光振幅変調）時にレ
ーザの直接変調により生ずるチャーピングに起因する伝
送特性劣化を避けることができるという効果を得られ
る。図５には本発明を実現するための光送信装置の第３
実施例を示す。本実施例では、光信号の変調にマッハツ
ェンダ型の変調器を用いている。マッハツェンダ型変調
器（ＭＺ型変調器）は原理的に２つの出力ポートを有
し、２つの出力ポートからの光パワーの和は一定値とな
る。即ち、第１のポートからの出力には、データに対応
した変調が施されており、第２出力ポートからは、該一
定値から第１出力ポートからのパワーを減算した残りの
光パワー（補信号）が出力されている。従って、各チャ
ネルの第２出力ポートからの光パワーの合計と、各チャ
ネルの第１出力ポートからの光パワーの合計（主信号の
パワーに比例）の和もやはり一定値となる。従って、第
２ポートからの出力パワーの合計に比例する光パワーの
信号を補償光信号とし、主信号に合波すると、上記第１
及び第２実施例の場合と同様に、光パワー一定の光信号
を光ファイバに送出することができ、クロス位相変調を
低減することができる。以上の原理を実現するため、図
５では、各変調器の第１出力ポートからの出力は合波器
に入力した後に増幅して主信号とし、第２出力ポートか
らの出力は他の合波器にて合波した後にそのパワーを受
光器にて検出している。さらに、該検出信号をドライブ
回路に入力し、該ドライブ回路は補償用変調器を変調し
ている。該変調器には、補償用レーザからの出力光が入
力している。該変調器からの出力光信号は光アンプにて
増幅され、補償光信号として出力され、合波器にて主信
号に合波され、光ファイバには光パワー一定の光信号が
送出される。本発明によれば第１実施例と同様の効果を
得ると同時に、チャーピングに起因する伝送特性劣化を
避けることができ、且つ、第１実施例の光パワー変化補
償回路に必要とされた減算器および加算器を省略できる
という効果も得る。図中の１−３は本実施例の光送信装
置全体を表している。なお、上記受光器により検出され
た信号は、第１及び第２実施例の場合と同様に、バイア
ス信号を加算し、ドライブ回路を用いて補償用レーザを
直接変調してもよい。なお、上記光送信装置１−１、
２、３において、光アンプは必要に応じて省略してもよ
い。図６には、図１、図４あるいは図５に示す光送信装
置１を用いた光ファイバ伝送システムの第１実施例を示
す。データ１〜データＮは該光送信装置により補償光信
号を合波した主信号に変換され、光ファイバに送出され
る。送出された光信号は図２（ｃ）に示すように一定の
光パワーを有している。光信号は、光ファイバを伝搬
後、光アンプ（エルビウムドープ光ファイバアンプ、半
導体アンプ等）にて増幅されて、後段の光ファイバにて
再び伝送される。このとき、チャネル１〜Ｎの光信号と
補償光信号の波長を光アンプの帯域内に設定しておけ
ば、各信号は同じ利得にて増幅されるため、該光アンプ
からの出力光信号のパワーもまた一定値となる。即ち、
クロス位相変調に起因する位相変化を１／（２Ｎ−１）
に抑圧することができるという効果を得る。光受信装置
では、光信号を光アンプにて増幅した後に分波器にて各
波長に分波し、各受信器にてデータ１〜データＮにそれ
ぞれ変換する。本実施例によれば、光中継増幅を用いた
光伝送システムにおいてもクロス位相変調低減の効果を
得ることができる。なお、本発明は、図６記載の構成の
みに限定されない。即ち、光アンプの段数はシステムに
要求される伝送距離により適宜偏光することができる。
例えば、短距離伝送の場合には、光アンプを用いなくて
もよい。また、光信号を途中で分岐あるいは分波して、
複数の光受信器に分配しても上記効果を得ることができ
る。図７（ａ）（ｂ）には、図１、図４あるいは図５に
示す光送信装置を用いた光ファイバ伝送システムの第２
実施例を示す。本実施例は、光パワー変化補償回路を光
アンプ（図中では、光パワー変化補償回路付光アンプ４
と表記）にも適用した伝送システムの実施例である。光
ファイバは波長分散を有するため、波長多重信号である
主信号を長距離伝送すると、チャネルごとに異なる伝搬
遅延を受ける。この結果、長距離伝送後の主信号の光パ
ワーの波形は、光送信装置における波形とは異なったも
のとなる。補償光信号は、光送信装置における主信号波
形を補償する波形を有しているため、長距離伝送後には
主信号波形変化を正確に補償することができない。本実
施例では、光中継増幅器にて主信号の波形変化に対応し
た新たな補償光信号を主信号に合波するものであり、光
ファイバに分散があってもクロス位相変調低減の効果を
有する。上記原理を実現するため、同図（ａ）の光パワ
ー変化補償回路付光アンプ４−１では、まず、送られて
きた光信号から主信号を光フィルタ（あるいは分波器）
にて分離し、主信号のみを光アンプにて増幅する。増幅
された主信号は、例えば、図１と同じ構成の光パワー変
化補償回路２−１にて、光パワー変化を補償する補償光
信号と合波され、パワー一定の光信号として光ファイバ
に送出される。なお、光フィルタと光アンプの順番は逆
でもよい。後段にも同様の構成の光パワー変化補償回路
付光アンプを用いれば、光ファイバによる伝送距離が長
距離化して、分散により主信号の波形が変化を受けて
も、光アンプ毎に新たな補償光信号を合波でき、光パワ
ーを一定に保てる。即ち、クロス位相変調を低減できる
という効果を得ることができる。なお、光パワー変化補
償回路の構成は、主信号のパワー変化を補償する補償光
信号を合波して出力できるのであれば、２−１以外の構
成であってもかまわない。図８（ａ）には、４−１に設
けた光フィルタの通過特性例を示す。同図のように、主
信号（チャネル１〜チャネルＮ）のみが光フィルタの帯
域内となっている。なお、光フィルタのかわりに分波器
を用いれば、補償用光信号も抽出でき、補償用光信号に
載せた情報（制御情報、監視信号、等）を検出すること
もできる。なお、図８（ｂ）に示すように、補償光信号
を光アンプの帯域外に設定しておけば、図７の分波器は
省略することができ、光パワー変化補償回路付光アンプ
の構成を簡易化できるという効果も得る。この場合の伝
送システムおよび光パワー変化補償回路付光アンプ４−
２の構成例を図７（ｂ）に示す。光送信装置および光受
信装置は、同図（ａ）の場合と同様である。DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a first embodiment of an optical transmitter for realizing the present invention. Data 1 to data N are combined after being converted into optical signals by lasers (lasers for transmission) having different wavelengths. The multiplexer can be realized by, for example, an optical filter using an optical coupler or a grating. The wavelength-multiplexed optical signal (main signal) obtained as the multiplexer output is amplified by the optical amplifier. The main signal output from the optical transmitter is input to the optical power change compensation circuit 2-1. In the compensation circuit, the main signal is first branched into two by a branching device. Let the optical power of the first main signal obtained by branching be P SUM (the maximum value is NP Max ), and the optical power of the second main signal be kP SUM.
(The maximum value is kNP Max , and k is a constant determined by the branching device). An example of the waveform of the optical power of the first main signal is shown in FIG.
Shown in. The second main signal is input to the light receiver. The light receiver receives a voltage (or current) signal Vp (=
kKP SUM and K output constants determined by the light receiver. The subtractor subtracts the signal Vp from the reference signal Vo and outputs the difference signal ΔV (= Vo-Vp). The value of Vo may be set to, for example, the maximum value kKNP Max of the signal Vp. At this time, the difference signal ΔV is kK (NP Max −
P SUM ). The adder adds the bias signal Vb to the difference signal ΔV and inputs the signal (Vb + ΔV) to the drive circuit. The drive circuit drives the compensation laser with a current proportional to the signal (Vb + ΔV). For example, if the signal Vb is set to a value corresponding to the threshold current of the laser, the laser will output an optical power kKL (NP Max) proportional to the difference signal ΔV.
-P SUM ) optical signal is output (L is a constant determined by the laser). Here, the wavelength of the compensation laser is set to a value different from that of the transmission laser. The optical signal from the compensation laser is amplified by an optical amplifier and the optical power gkKL (N
Output as a compensation optical signal of (P Max −P SUM ) (g
Is the gain of the optical amplifier). Here, if the constants g, k, K, and L are set so that the constant product gkKL is equal to 1,
The power of the compensation optical signal output from the optical amplifier becomes equal to P C in equation (3) (a waveform example is shown in FIG. 2B). Therefore, when this compensating optical signal is multiplexed with the first main signal, an optical signal with a constant optical power as shown in FIG. 2C can be obtained, and as a result, the phase change amount is expressed by the formula (6).
Can be reduced to 1 / (2N-1). That is, this embodiment can reduce the cross phase modulation,
The effect that the deterioration of the transmission characteristics can be reduced is obtained. 1
-1 represents the entire optical transmitter of the present embodiment. In addition,
FIG. 3 shows an example of spectrum arrangement of the main signal and the compensation optical signal. As shown in the figure, the compensating optical signal may be arranged on the shorter wavelength side than the main signal (channel 1 to channel N) ((a) in the figure) or on the long wavelength side ((b) in the figure). )), And even if it is arranged between the channels forming the main signal (between channel n and channel n + 1 in the figure (c), where 1 ≦ n ≦ N), the above effect can be obtained. it can. FIG. 4 shows a second embodiment of the optical transmitter for realizing the present invention. The difference between this embodiment and the first embodiment is that the change in the optical power of the main signal is caused by the change of the electrical signal (data 1 to data 1
It is indirectly obtained by detecting the data N). As shown in FIG. 4, each data signal is divided into two before modulation of the laser, one is used for modulation of the laser, and the other is input to the optical power change compensation circuit. The optical signal output from each laser is multiplexed by the multiplexer as in the first embodiment, amplified by the optical amplifier, and then output as the main signal (the waveform is the same as in FIG. 2A). On the other hand, the data 1 to data N input to the optical power change compensation circuit are added by an adder and then input to a subtractor to detect a difference from a reference value (for example, N). The adder at the subsequent stage adds the bias value to the output of the subtractor and inputs it to the drive circuit. The drive circuit drives the compensating laser, and the compensating optical signal (waveform diagram 2
(B)) is output. Finally, the main signal and the compensation optical signal are combined by a combiner and sent to an optical fiber. At this time, since the waveform of the compensation optical signal is a waveform that compensates for the change in the main signal, the sum of the main signal and the compensation optical signal has a constant value. That is, since the optical signal having the waveform shown in FIG. 2C is transmitted to the optical fiber, the phase change due to the cross phase modulation is reduced to 1 / (2N) as shown in equation (6).
-1) can be suppressed. In addition, 1-2 in the figure represents the entire optical transmitter of the present embodiment. It should be noted that in the present embodiment, when the bit synchronization between the data signals is established, the addition of the branch data becomes easier. In the first and second embodiments, the optical signal is modulated by direct modulation of the laser (light intensity modulation, optical amplitude modulation, optical frequency modulation, etc.). Modulation to an optical signal may be realized. The modulator can be realized by, for example, an electro-absorption type or Mach-Zehnder type modulator. The modulator receives light of constant power output from the laser as input, and modulates the input light (light intensity modulation, light amplitude modulation, optical phase modulation, etc.) according to the electrical signal applied to the modulator. Output. The use of the modulator has an effect of avoiding the deterioration of the transmission characteristic due to the chirping caused by the direct modulation of the laser during the light intensity modulation (or the light amplitude modulation). FIG. 5 shows a third optical transmitter for realizing the present invention.
An example is shown. In this embodiment, a Mach-Zehnder type modulator is used to modulate the optical signal. The Mach-Zehnder modulator (MZ modulator) has two output ports in principle, and the sum of the optical powers from the two output ports has a constant value. That is, the output from the first port is subjected to modulation corresponding to the data, and the second output port subtracts the power from the first output port from the constant value to obtain the remaining optical power (compensation). Signal) is being output. Therefore, the sum of the total optical power from the second output port of each channel and the total optical power from the first output port of each channel (proportional to the power of the main signal) is also a constant value. Therefore, when a signal of optical power proportional to the total output power from the second port is used as a compensation optical signal and multiplexed with the main signal,
Also, as in the case of the second embodiment, an optical signal with a constant optical power can be sent to the optical fiber, and cross phase modulation can be reduced. In order to realize the above principle, in FIG. 5, the output from the first output port of each modulator is input to the multiplexer and then amplified to be the main signal, and the output from the second output port is combined with other multiplexers. The power is detected by the photodetector after being combined by the optical receiver. Further, the detection signal is input to the drive circuit, and the drive circuit modulates the compensation modulator. Output light from the compensation laser is input to the modulator. An optical signal output from the modulator is amplified by an optical amplifier, output as a compensation optical signal, multiplexed by a multiplexer into a main signal, and an optical signal having a constant optical power is sent to an optical fiber. According to the present invention, the same effect as that of the first embodiment can be obtained, at the same time, the deterioration of the transmission characteristics due to the chirping can be avoided, and the subtraction required for the optical power change compensating circuit of the first embodiment can be avoided. It is also possible to omit the adder and the adder. Reference numeral 1-3 in the figure represents the entire optical transmitter of the present embodiment. Note that the signals detected by the photodetector may be added with bias signals and the compensation laser may be directly modulated by using a drive circuit, as in the first and second embodiments. In addition, the optical transmitter 1-1,
In 2 and 3, the optical amplifier may be omitted if necessary. FIG. 6 shows a first embodiment of an optical fiber transmission system using the optical transmitter 1 shown in FIG. 1, 4 or 5. The data 1 to data N are converted by the optical transmitter into a main signal that is a combination of the compensation optical signals and are sent to the optical fiber. The transmitted optical signal has a constant optical power as shown in FIG. After propagating through the optical fiber, the optical signal is amplified by an optical amplifier (erbium-doped optical fiber amplifier, semiconductor amplifier, etc.) and is transmitted again by the optical fiber at the subsequent stage. At this time, if the wavelengths of the optical signals of channels 1 to N and the compensation optical signal are set within the band of the optical amplifier, each signal is amplified with the same gain, so that the output optical signal of the optical amplifier is The power also becomes a constant value. That is,
Phase change due to cross phase modulation is 1 / (2N-1)
The effect of being able to be suppressed is obtained. In the optical receiving device, an optical signal is amplified by an optical amplifier, then demultiplexed into wavelengths by a demultiplexer, and converted into data 1 to data N by each receiver. According to this embodiment, the effect of reducing cross phase modulation can be obtained even in an optical transmission system using optical repeater amplification. The present invention is not limited to the configuration shown in FIG. That is, the number of stages of the optical amplifier can be appropriately polarized according to the transmission distance required for the system.
For example, in the case of short distance transmission, the optical amplifier may not be used. In addition, the optical signal is branched or split in the middle,
The above effect can be obtained by distributing the light to a plurality of optical receivers. 7 (a) and 7 (b) shows a second optical fiber transmission system using the optical transmitter shown in FIG. 1, FIG. 4 or FIG.
An example is shown. In this embodiment, the optical power change compensation circuit is provided with an optical amplifier (in the figure, an optical amplifier with an optical power change compensation circuit 4
Is also applied to the above). Since the optical fiber has chromatic dispersion, long-distance transmission of the main signal, which is a wavelength-multiplexed signal, causes a different propagation delay for each channel. As a result, the waveform of the optical power of the main signal after long-distance transmission becomes different from the waveform in the optical transmitter. Since the compensation optical signal has a waveform that compensates for the main signal waveform in the optical transmitter, it is not possible to accurately compensate for the main signal waveform change after long-distance transmission. In the present embodiment, a new compensating optical signal corresponding to the waveform change of the main signal is multiplexed with the main signal in the optical repeater amplifier, and even if there is dispersion in the optical fiber, it has the effect of reducing cross phase modulation. . In order to realize the above principle, in the optical amplifier 4-1 with the optical power change compensating circuit in the same figure (a), first, the main signal from the transmitted optical signal is converted into an optical filter (or demultiplexer).
, And the main signal is amplified by an optical amplifier. The amplified main signal is combined with a compensating optical signal for compensating the optical power change in the optical power change compensating circuit 2-1 having the same configuration as in FIG. 1, and is sent to the optical fiber as an optical signal of constant power. To be done. The order of the optical filter and the optical amplifier may be reversed. If an optical amplifier with optical power change compensation circuit of similar configuration is used in the latter stage, even if the transmission distance by the optical fiber becomes long and the waveform of the main signal changes due to dispersion, new compensation is provided for each optical amplifier. The optical signals can be combined and the optical power can be kept constant. That is, the effect of reducing the cross phase modulation can be obtained. The optical power change compensation circuit may have a configuration other than 2-1 as long as the compensated optical signal for compensating the power change of the main signal can be multiplexed and output. FIG. 8A shows an example of pass characteristics of the optical filter provided in 4-1. As shown in the figure, only the main signal (channel 1 to channel N) is within the band of the optical filter. If a demultiplexer is used instead of the optical filter, the compensating optical signal can also be extracted and the information (control information, monitoring signal, etc.) included in the compensating optical signal can be detected. As shown in FIG. 8B, if the compensating optical signal is set outside the band of the optical amplifier, the demultiplexer of FIG. 7 can be omitted and the optical amplifier with the optical power change compensating circuit can be omitted. The effect that the configuration can be simplified is also obtained. Transmission system and optical amplifier with optical power change compensation circuit in this case 4-
FIG. 7B shows a configuration example of No. 2. The optical transmitter and the optical receiver are the same as in the case of FIG.
【発明の効果】本発明によれば、光ファイバ中を伝搬す
る光信号のパワーを一定にできるので、クロス位相変調
を低減でき、伝送特性劣化を低減できるという効果を得
る。According to the present invention, the power of an optical signal propagating in an optical fiber can be made constant, so that cross phase modulation can be reduced and deterioration of transmission characteristics can be reduced.
【図１】本発明の光送信装置の第１実施例。FIG. 1 shows a first embodiment of an optical transmitter according to the present invention.
【図２】本発明の光送信装置各部における光パワーの波
形。FIG. 2 is a waveform of optical power in each part of the optical transmitter of the present invention.
【図３】本発明における主信号および補償光信号のスペ
クトル配置例。FIG. 3 is an example of spectrum arrangement of a main signal and a compensation optical signal in the present invention.
【図４】本発明の光送信装置の第２実施例。FIG. 4 shows a second embodiment of the optical transmitter of the present invention.
【図５】本発明の光送信装置の第３実施例。FIG. 5 shows a third embodiment of the optical transmitter of the present invention.
【図６】本発明の伝送システムの第１実施例。FIG. 6 is a first embodiment of the transmission system of the present invention.
【図７】本発明の伝送システムの第２実施例。FIG. 7 shows a second embodiment of the transmission system of the present invention.
【図８】図７における光フィルタ通過域特性および光ア
ンプ帯域特性の例。8 is an example of an optical filter pass band characteristic and an optical amplifier band characteristic in FIG.
１…光送信装置、２…光パワー変化補償回路、３…光受
信装置、４…光パワー変化補償回路付光アンプ。DESCRIPTION OF SYMBOLS 1 ... Optical transmitter, 2 ... Optical power change compensation circuit, 3 ... Optical receiver, 4 ... Optical power change compensation circuit equipped optical amplifier.
Claims (16)
主信号の光パワーの変化分ΔＰを検出する手段と、該主
信号とは異なる波長を有し、且つ、光パワーが略（Ｐ0
−ΔＰ）である補償光信号（Ｐ0は定数、Ｐ0≧ΔＰ）を
出力する手段と、該主信号と該補償光信号を合波して、
光パワーが一定値Ｐ0である光信号を出力する手段とか
ら構成されることを特徴とする光パワー変化補償回路。1. A means for inputting a wavelength-multiplexed optical signal (main signal) and detecting a change amount ΔP of the optical power of the main signal, and a wavelength different from that of the main signal, and the optical power is substantially the same. (P 0
Means for outputting a compensation optical signal (P 0 is a constant, P 0 ≧ ΔP) that is −ΔP), and the main signal and the compensation optical signal are multiplexed,
And a means for outputting an optical signal having a constant optical power P 0 .
２主信号に分岐する分岐器と、第２主信号を入力とし
て、該主信号の光パワーに比例する電気信号を出力する
受光器と、基準信号から該電気信号を減算する減算器
と、該減算器からの出力信号にバイアス信号を加算する
加算器と、該加算器からの出力信号に比例する電流にて
レーザを駆動するドライブ回路と、該ドライブ回路によ
り駆動されて、ドライブ電流から閾値電流を差し引いた
電流にほぼ比例するパワーの光信号（補償光信号）を出
力するレーザと、該補償光信号と上記第１主信号とを合
波する合波器とから構成され、該合波器からの出力光信
号は略一定の光パワーを有することを特徴とする光パワ
ー変化補償回路。2. A branching device for branching a wavelength-multiplexed optical signal (main signal) into first and second main signals, and an electric signal proportional to the optical power of the main signal when the second main signal is input. A light receiver, a subtractor for subtracting the electric signal from a reference signal, an adder for adding a bias signal to the output signal from the subtractor, and a laser driven by a current proportional to the output signal from the adder Drive circuit, a laser which is driven by the drive circuit, and which outputs an optical signal (compensation optical signal) having a power substantially proportional to the current obtained by subtracting the threshold current from the drive current, the compensation optical signal, and the first main signal. An optical power change compensating circuit comprising: a multiplexer for multiplexing a signal and an optical signal output from the multiplexer has a substantially constant optical power.
２主信号に分岐する分岐器と、第２主信号を入力とし
て、該主信号の光パワーに比例する電気信号を出力する
受光器と、該電気信号に比例する電圧あるいは電流信号
により補償用変調器を変調して補償光信号を出力する変
調器と、上記主信号とは異なる波長を有し、且つ、該変
調器に光を入力する半導体レーザと、該補償光信号と上
記第１主信号とを合波する合波器とから構成され、該合
波器からの出力光信号は略一定の光パワーを有すること
を特徴とする光パワー変化補償回路。3. A branching device for branching a wavelength-multiplexed optical signal (main signal) into first and second main signals, and an electric signal proportional to the optical power of the main signal, with the second main signal as an input. A light receiver, a modulator for modulating a compensation modulator with a voltage or current signal proportional to the electric signal to output a compensation optical signal, and a wavelength different from that of the main signal, and the modulator It is composed of a semiconductor laser for inputting light and a multiplexer for multiplexing the compensation optical signal and the first main signal, and the output optical signal from the multiplexer has a substantially constant optical power. Characteristic optical power change compensation circuit.
より直接変調されて光信号を出力する複数台の半導体レ
ーザと、該レーザからの光信号を合波して波長多重信号
（主信号）を出力する合波器と、該波長多重信号を入力
とする請求項１乃至３記載のいずれかの光パワー変化補
償回路とから構成されることを特徴とする光送信装置。4. A plurality of semiconductor lasers which have different wavelengths and which are directly modulated by an electric signal to output an optical signal, and an optical signal from the lasers are combined to generate a wavelength multiplexed signal (main signal). An optical transmitter comprising: an output multiplexer and the optical power change compensating circuit according to any one of claims 1 to 3, which receives the wavelength-multiplexed signal as an input.
ザと、該レーザからの出力光にそれぞれ変調を施して光
信号を出力する変調器と、該レーザからの光信号を合波
して波長多重信号（主信号）を出力する合波器と、該波
長多重信号を入力とする請求項１乃至３記載のいずれか
の光パワー変化補償回路とから構成されることを特徴と
する光送信装置。5. A plurality of semiconductor lasers having different wavelengths, a modulator for modulating the output light from each of the lasers to output an optical signal, and a wavelength multiplexing by multiplexing the optical signals from the lasers. An optical transmitter comprising: a multiplexer that outputs a signal (main signal); and the optical power change compensation circuit according to any one of claims 1 to 3 that receives the wavelength-multiplexed signal as an input.
電気信号に分岐する分岐器と、波長がそれぞれ異なり、
且つ、該第１電気信号によりそれぞれ直接変調されて光
信号を出力する複数の半導体レーザと、該レーザからの
光信号を合波して波長多重信号（主信号）を出力する合
波器と、該第２電気信号を加算する加算器と、基準値か
ら該加算値を減算する減算器と、該減算器からの出力信
号にバイアス信号を加算する加算器と、該加算器からの
出力信号に比例する電流にてレーザを駆動するドライブ
回路と、該ドライブ回路により駆動されて、ドライブ電
流から閾値電流を差し引いた電流にほぼ比例するパワー
の補償光信号を出力するレーザと、該補償光信号と上記
主信号とを合波する合波器とから構成され、該合波器か
らの出力光信号は略一定の光パワーを有することを特徴
とする光送信装置。6. A plurality of electrical signals are provided as first and second electrical signals, respectively.
The wavelength is different from that of the branching device that splits the signal into electrical signals.
Also, a plurality of semiconductor lasers each of which is directly modulated by the first electric signal to output an optical signal, and a multiplexer that multiplexes the optical signals from the lasers and outputs a wavelength multiplexed signal (main signal), An adder for adding the second electric signal, a subtractor for subtracting the added value from a reference value, an adder for adding a bias signal to the output signal from the subtractor, and an output signal from the adder A drive circuit that drives a laser with a proportional current, a laser that is driven by the drive circuit, and that outputs a compensation optical signal with a power that is approximately proportional to the current obtained by subtracting the threshold current from the drive current, and the compensation optical signal. An optical transmitter comprising: a multiplexer that multiplexes the main signal, and an optical signal output from the multiplexer has a substantially constant optical power.
電気信号に分岐する分岐器と、波長がそれぞれ異なる複
数台の半導体レーザと、該レーザからの出力光に上記第
１電気信号によりそれぞれ変調を施して光信号を出力す
る変調器と、該変調器からの光信号を合波して波長多重
信号（主信号）を出力する合波器と、該第２電気信号を
加算する加算器と、基準値から該加算値を減算する減算
器と、該減算器からの出力信号に比例する電圧あるいは
電流信号により補償用変調器を変調して補償光信号を出
力する変調器と、上記主信号とは異なる波長を有し、且
つ、該変調器に光を入力する半導体レーザと、該補償光
信号と上記主信号とを合波する合波器とから構成され、
該合波器からの出力光信号は略一定の光パワーを有する
ことを特徴とする光送信装置。7. A plurality of electrical signals are provided as first and second electrical signals, respectively.
A branching device for branching into an electric signal, a plurality of semiconductor lasers each having a different wavelength, a modulator for modulating output light from the laser with the first electric signal and outputting an optical signal, and the modulator A multiplexer that multiplexes the optical signals from the above to output a wavelength multiplexed signal (main signal), an adder that adds the second electric signal, a subtractor that subtracts the added value from a reference value, A modulator that modulates the compensating modulator with a voltage or current signal proportional to the output signal from the subtractor and outputs a compensating optical signal, and a wavelength that is different from the main signal, and A semiconductor laser for inputting, and a multiplexer for multiplexing the compensation optical signal and the main signal,
An optical transmitter, wherein an output optical signal from the multiplexer has a substantially constant optical power.
ザと、該レーザからの出力光に変調を施した光信号とそ
の補信号を出力するマッハツェンダ型変調器と、該レー
ザからの光信号を合波して波長多重信号（主信号）を出
力する第１合波器と、該補信号を合波する第２合波器
と、該第２合波器からの出力信号の光パワーに比例する
電気信号を出力する受光器と、該受光器からの出力信号
に比例する電圧あるいは電流信号により補償用変調器を
変調して補償光信号を出力する変調器と、上記主信号と
は異なる波長を有し、且つ、該変調器に光を入力する半
導体レーザと、該補償光信号と上記第１主信号とを合波
する合波器とから構成され、該合波器からの出力光信号
は略一定の光パワーを有することを特徴とする光送信装
置。8. A plurality of semiconductor lasers having different wavelengths, a Mach-Zehnder type modulator for outputting an optical signal obtained by modulating the output light from the laser and its complementary signal, and an optical signal from the laser are combined. It is proportional to the optical power of the first multiplexer that outputs the wavelength-multiplexed signal (main signal) by wave, the second multiplexer that combines the complementary signal, and the optical power of the output signal from the second multiplexer. A light receiver that outputs an electrical signal, a modulator that modulates the compensation modulator with a voltage or current signal proportional to the output signal from the light receiver to output a compensation optical signal, and a wavelength different from the main signal And a semiconductor laser for inputting light into the modulator, and a multiplexer for multiplexing the compensation optical signal and the first main signal, and the output optical signal from the multiplexer is An optical transmitter having a substantially constant optical power.
アンプを有することを特徴とする請求項４乃至８記載の
いずれかの光送信装置。9. The optical transmitter according to claim 4, further comprising an optical amplifier for amplifying the main signal and the compensation optical signal.
装置と、該光送信装置からの出力信号を伝送する光ファ
イバと、該光ファイバからの出力信号を各波長に分波す
る分波器と、分波された各波長の光信号を電気信号にそ
れぞれ変換する受信器とから構成されることを特徴とす
る光伝送装置。10. An optical transmitter according to any one of claims 4 to 9, an optical fiber for transmitting an output signal from the optical transmitter, and a component for demultiplexing the output signal from the optical fiber into respective wavelengths. An optical transmission device comprising a wave filter and a receiver for converting an optical signal of each demultiplexed wavelength into an electric signal.
装置と、該光送信装置からの出力信号を伝送する光ファ
イバと、該光ファイバからの出力信号を増幅する光アン
プと、該光アンプからの出力信号を伝送する光ファイバ
と、該光ファイバからの出力信号を各波長に分波する分
波器と、分波された各波長の光信号を電気信号にそれぞ
れ変換する受信器とから構成されることを特徴とする光
伝送装置。11. An optical transmitter according to claim 4, an optical fiber for transmitting an output signal from the optical transmitter, an optical amplifier for amplifying an output signal from the optical fiber, An optical fiber that transmits an output signal from an optical amplifier, a demultiplexer that demultiplexes the output signal from the optical fiber into each wavelength, and a receiver that converts the demultiplexed optical signal of each wavelength into an electrical signal. An optical transmission device comprising:
装置と、該光送信装置からの出力信号を伝送する光ファ
イバと、該光ファイバからの出力信号を中継増幅する光
アンプと、該光アンプからの出力信号を伝送する光ファ
イバと、該光ファイバからの出力信号を増幅する光アン
プと、該光アンプからの出力信号を各波長に分波する分
波器と、分波された各波長の光信号を電気信号にそれぞ
れ変換する受信器とから構成されることを特徴とする光
伝送装置。12. An optical transmitter according to claim 4, an optical fiber for transmitting an output signal from the optical transmitter, and an optical amplifier for relaying and amplifying an output signal from the optical fiber. An optical fiber that transmits the output signal from the optical amplifier, an optical amplifier that amplifies the output signal from the optical fiber, a demultiplexer that demultiplexes the output signal from the optical amplifier into each wavelength, and a demultiplexer. An optical transmission device comprising: a receiver that converts an optical signal of each wavelength into an electrical signal.
号（主信号）から主信号を抽出する光フィルタと、抽出
された主信号を増幅する光アンプと、増幅された主信号
を入力とする請求項１乃至３記載のいずれかの光パワー
変化補償回路とから構成されることを特徴とする光パワ
ー変化補償回路付光アンプ。13. An optical filter for extracting a main signal from a wavelength-multiplexed signal (main signal) to which a compensation optical signal is multiplexed, an optical amplifier for amplifying the extracted main signal, and an amplified main signal as an input. An optical amplifier with an optical power change compensating circuit, comprising: the optical power change compensating circuit according to claim 1.
号（主信号）を入力とし、且つ、該主信号は帯域内で、
しかも、該補償光信号は帯域外となる増幅帯域を有する
光アンプと、増幅された主信号を入力とする請求項１乃
至３記載のいずれかの光パワー変化補償回路とから構成
されることを特徴とする光パワー変化補償回路付光アン
プ。14. A wavelength-multiplexed signal (main signal) to which a compensation optical signal is multiplexed is input, and the main signal is within a band,
Moreover, the compensation optical signal is composed of an optical amplifier having an amplification band that is out of the band, and the optical power change compensation circuit according to any one of claims 1 to 3, which receives the amplified main signal. An optical amplifier with a characteristic optical power change compensation circuit.
て、請求項１３乃至１４記載のいずれかの光パワー変化
補償回路付光アンプを用いることを特徴とする光伝送装
置。15. An optical transmission apparatus using the optical amplifier with optical power change compensation circuit according to claim 13 as the relay amplification optical amplifier according to claim 12.
ト同期がとれていることを特徴とする光送信装置。16. An optical transmitter according to claim 6, wherein the electric signals are bit-synchronized with each other.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4281362A JPH06132895A (en) | 1992-10-20 | 1992-10-20 | Optical power change compensating circuit and optical transmitter |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4281362A JPH06132895A (en) | 1992-10-20 | 1992-10-20 | Optical power change compensating circuit and optical transmitter |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH06132895A true JPH06132895A (en) | 1994-05-13 |
Family
ID=17638060
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4281362A Pending JPH06132895A (en) | 1992-10-20 | 1992-10-20 | Optical power change compensating circuit and optical transmitter |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH06132895A (en) |
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|---|---|---|---|---|
| JPH06152034A (en) * | 1992-11-06 | 1994-05-31 | Sumitomo Cement Co Ltd | Dummy light input controlled optical fiber amplification |
| JPH0918453A (en) * | 1995-06-26 | 1997-01-17 | Kokusai Denshin Denwa Co Ltd <Kdd> | Noise suppressing method for wavelength multiplex transmission system |
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- 1992-10-20 JP JP4281362A patent/JPH06132895A/en active Pending
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|---|---|---|---|---|
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| JPH0918453A (en) * | 1995-06-26 | 1997-01-17 | Kokusai Denshin Denwa Co Ltd <Kdd> | Noise suppressing method for wavelength multiplex transmission system |
| US6064514A (en) * | 1995-10-30 | 2000-05-16 | Nec Corporation | Optical surge preventing method and system for use with or in a rare earth doped fiber circuit |
| JPH09130328A (en) * | 1995-10-30 | 1997-05-16 | Nec Corp | Method and equipment for optical transmission |
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| EP0855586A1 (en) * | 1996-07-29 | 1998-07-29 | Ando Electric Co., Ltd. | Wavelength dependence correction method in optical variable attenuator |
| EP0855586A4 (en) * | 1996-07-29 | 2000-03-29 | Ando Electric | Wavelength dependence correction method in optical variable attenuator |
| EP0838913A3 (en) * | 1996-10-23 | 2000-10-11 | Nortel Networks Limited | Stable power control for optical transmission systems |
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| US6268945B1 (en) | 1996-10-23 | 2001-07-31 | Nortel Networks Limited | Stable power control for optical transmission systems |
| JPH10154961A (en) * | 1996-11-22 | 1998-06-09 | Nec Corp | Optical transmitter and optical communication system |
| JPH11205227A (en) * | 1998-01-14 | 1999-07-30 | Nec Corp | Optical fiber amplifier surge protection circuit |
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| EP0946006A1 (en) * | 1998-03-26 | 1999-09-29 | Lucent Technologies Inc. | Method and apparatus for controlling the optical power of an optical wavelength division multiplexed transmission signal |
| US6873456B2 (en) * | 1999-07-30 | 2005-03-29 | Mitsubishi Denki Kabushiki Kaisha | Optical amplifying repeater apparatus and optical amplifying/repeating transmission system |
| US6798565B2 (en) * | 2000-08-16 | 2004-09-28 | Siemens Aktiengesellschaft | Method and arrangement for compensating for cross phase modulation |
| KR100353845B1 (en) * | 2000-12-27 | 2002-09-28 | 한국전자통신연구원 | Wavelength Converter based on cross-phase modulation using SOA, and its Method |
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