JP4630047B2 - Optical transmission equipment - Google Patents

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JP4630047B2
JP4630047B2 JP2004354355A JP2004354355A JP4630047B2 JP 4630047 B2 JP4630047 B2 JP 4630047B2 JP 2004354355 A JP2004354355 A JP 2004354355A JP 2004354355 A JP2004354355 A JP 2004354355A JP 4630047 B2 JP4630047 B2 JP 4630047B2
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optical modulation
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JP2006166004A (en
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豊 板倉
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Hitachi Kokusai Electric Inc
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本発明は、電気信号を光信号に変換して信号の送信を行う光伝送装置、特に電気／光（Ｅ／Ｏ）変換部に関するものである。   The present invention relates to an optical transmission device that converts an electrical signal into an optical signal and transmits the signal, and more particularly to an electrical / optical (E / O) conversion unit.

光伝送に於いては、信号伝達の安定性、信頼性を維持する為、電気／光変換した場合に光変調度（ＯＭＩ：Ｏｐｔｉｃａｌ Ｍｏｄｕｌａｔｉｏｎ Ｉｎｄｅｘ）を一定に保つ必要がある。   In optical transmission, in order to maintain the stability and reliability of signal transmission, it is necessary to keep the optical modulation index (OMI) constant when electrical / optical conversion is performed.

従来、Ｅ／Ｏで変換された光信号の光変調度を一定に制御可能な光伝送装置として特許文献１に示されるものがある。   2. Description of the Related Art Conventionally, an optical transmission apparatus that can control the optical modulation degree of an optical signal converted by E / O to be constant is disclosed in Patent Document 1.

特許文献１には光受信装置が光伝送路で接続され、光送信装置でＥ／Ｏ変換された光信号が光受信装置で受信され、光／電気（Ｏ／Ｅ）変換される光伝送装置が示されている。   Patent Document 1 discloses an optical transmission device in which an optical receiving device is connected through an optical transmission line, and an optical signal that has been E / O converted by the optical transmission device is received by the optical receiving device and optical / electrical (O / E) conversion is performed. It is shown.

Ｅ／Ｏ変換部、特にレーザダイオード（ＬＤ）は入力される高周波電気信号のゲイン、或はＬＤ自体の温度変化で光変調度に影響を及し、又ＬＤに印加するバイアス電流により光変調度に変動を与えることができることから、特許文献１のＥ／Ｏ変換部では、ＬＤのバイアス電流をモニタし、モニタした結果に基づき、Ｅ／Ｏ変換された光変調度が一定となる様に、入力される高周波電気信号のゲインを調整している。   The E / O converter, particularly the laser diode (LD), affects the optical modulation factor by the gain of the input high-frequency electrical signal or the temperature change of the LD itself, and the optical modulation factor by the bias current applied to the LD. Therefore, the E / O converter of Patent Document 1 monitors the bias current of the LD, and based on the monitored result, the E / O converted light modulation degree is constant. The gain of the input high-frequency electrical signal is adjusted.

一方、光伝送装置は様々な環境に設置され、設置場所、設置環境によって、要求されるＥ／Ｏ変換条件が異なる。例えば、光伝送区間の３次歪み（ＩＭ３：３ｒｄ ｏｒｄｅｒ Ｉｎｔｅｒ Ｍｏｄｕｌａｔｉｏｎ）を少なくする、或は雑音（ＣＮＲ：Ｃａｒｒｉｅｒ ｔｏ Ｎｏｉｓｅ Ｒａｔｉｏ）を低減したいという要求がある。この場合、従来の光伝送装置の様にＥ／Ｏ変換部で変換した場合の光変調度を一定となる様一義的に制御する方法であると、それぞれの光伝送装置毎に、また設置条件毎に手動で設定しなければならず、面倒であり、設置環境毎に最適なＥ／Ｏ変換条件を実現することが難しいという問題があった。   On the other hand, optical transmission apparatuses are installed in various environments, and required E / O conversion conditions differ depending on the installation location and installation environment. For example, there is a demand to reduce third-order distortion (IM3: 3rd order Inter Modulation) in an optical transmission section or to reduce noise (CNR: Carrier to Noise Ratio). In this case, as in the conventional optical transmission apparatus, the method of uniquely controlling the optical modulation degree when converted by the E / O conversion unit to be constant, for each optical transmission apparatus, installation conditions There is a problem that it must be set manually every time, and is troublesome, and it is difficult to realize optimum E / O conversion conditions for each installation environment.

特開２００２−３３７０５号公報JP 2002-33705 A

本発明は斯かる実情に鑑み、光変調度の調整が可能で、設置場所、設置環境に応じて最適な光変調度が容易に得られる光伝送装置を提供するものである。   In view of such circumstances, the present invention provides an optical transmission apparatus that can adjust the light modulation degree and can easily obtain the optimum light modulation degree according to the installation location and the installation environment.

本発明は、電気信号を光信号に変換するレーザダイオードと、該レーザダイオードに入力される信号の減衰率を調整する光変調度調整手段と、前記レーザダイオードのバイアス電流を検出するバイアス電流検出部と、検出されたバイアス電流に基づき設定された光変調度となる様に前記光変調度調整手段の減衰率を制御する演算処理部と、該演算処理部に光変調度の設定値を入力するＯＭＩ設定部を具備した光伝送装置に係るものである。   The present invention includes a laser diode that converts an electrical signal into an optical signal, an optical modulation degree adjusting unit that adjusts an attenuation rate of a signal input to the laser diode, and a bias current detection unit that detects a bias current of the laser diode. And an arithmetic processing unit that controls the attenuation factor of the optical modulation degree adjusting means so that the optical modulation degree is set based on the detected bias current, and a setting value of the optical modulation degree is input to the arithmetic processing unit The present invention relates to an optical transmission apparatus including an OMI setting unit.

本発明によれば、電気信号を光信号に変換するレーザダイオードと、該レーザダイオードに入力される信号の減衰率を調整する光変調度調整手段と、前記レーザダイオードのバイアス電流を検出するバイアス電流検出部と、検出されたバイアス電流に基づき設定された光変調度となる様に前記光変調度調整手段の減衰率を制御する演算処理部と、該演算処理部に光変調度の設定値を入力するＯＭＩ設定部を具備したので、光変調度を設置場所、設置環境に応じて設定することができ、最適な光変調度が得られるという優れた効果を発揮する。   According to the present invention, a laser diode that converts an electrical signal into an optical signal, a light modulation degree adjusting means that adjusts an attenuation rate of a signal input to the laser diode, and a bias current that detects a bias current of the laser diode A detection unit, an arithmetic processing unit for controlling the attenuation factor of the optical modulation degree adjusting means so as to obtain an optical modulation degree set based on the detected bias current, and a set value of the optical modulation degree in the arithmetic processing unit. Since the input OMI setting unit is provided, the light modulation degree can be set according to the installation location and the installation environment, and an excellent effect of obtaining the optimum light modulation degree is exhibited.

以下、図面を参照しつつ本発明を実施する為の最良の形態を説明する。   The best mode for carrying out the present invention will be described below with reference to the drawings.

光伝送装置に於いて、光区間の３次歪み（ＩＭ３：３ｒｄ ｏｒｄｅｒ Ｉｎｔｅｒ Ｍｏｄｕｌａｔｉｏｎ）と雑音（ＣＮＲ：Ｃａｒｒｉｅｒ ｔｏ Ｎｏｉｓｅ Ｒａｔｉｏ）を決定するのは光変調度（ＯＭＩ：Ｏｐｔｉｃａｌ Ｍｏｄｕｌａｔｉｏｎ Ｉｎｄｅｘ）であり、ＯＭＩは光強度の変調振幅と平均光強度の比で定義され、下記（１）式で定義される。   In the optical transmission apparatus, it is the optical modulation index (OMI) that determines the third-order distortion (IM3: 3rd order Inter Modulation) and noise (CNR: Carrier to Noise Ratio) of the optical section, and the OMI (OMI: Optical Modulation Index). Is defined by the ratio between the modulation amplitude of the light intensity and the average light intensity, and is defined by the following equation (1).

ＯＭＩ＝（光強度の変調振幅／平均光強度）
＝(Ｐpeak−Ｐave）／Ｐave
＝√（２ＰRF／ＺLD）／（Ｉb−Ｉth） …（１）
ここで、Ｐpeak：光強度の変調振幅
Ｐave ：平均光強度
ＰRF ：キャリア１波当りのＬＤ入力レベル
ＺLD ：ＬＤの入力インピーダンス
Ｉb ：バイアス電流
Ｉth ：閾値電流 OMI = (modulation amplitude of light intensity / average light intensity)
= (Ppeak-Pave) / Pave
= √ (2PRF / ZLD) / (Ib−Ith) (1)
Where Ppeak: modulation amplitude of light intensity
Pave: Average light intensity
PRF: LD input level per carrier wave
ZLD: LD input impedance
Ib: Bias current
Ith: threshold current

又、（１）式に於いて、ＺLD、Ｉb 、Ｉthは各ＬＤに対して固定値となるので、ＩＭ３及びＣＮＲの検討の際に変動可能なパラメータはＰRFのみである。従って、ＰRFの増減に対してＯＭＩが増減し、例えばＯＭＩを大きくする場合は、ＬＤの入力レベル、即ちＰRFを増大させればよい。   In the equation (1), ZLD, Ib, and Ith are fixed values for each LD. Therefore, the only parameter that can be changed when examining IM3 and CNR is PRF. Therefore, the OMI increases or decreases with respect to the increase or decrease of the PRF. For example, when the OMI is increased, the input level of the LD, that is, the PRF may be increased.

次に、光伝送区間のＩＭ３、ＣＮＲ及び利得（Ｇopt）は下記（２）式、（３）式及び（４）式で示される。   Next, IM3, CNR, and gain (Gopt) in the optical transmission section are expressed by the following equations (2), (3), and (4).

ＩＭ３＝ＩＭ３ref ＋４０ｌｏｇ（ＯＭＩ／ＯＭＩref） …（２）
ここで、ＩＭ３ref ：ＯＭＩref で変調した時のＩＭ３
ＯＭＩref ：基準となるＯＭＩ、例えば０．２ IM3 = IM3ref + 40 log (OMI / OMIref) (2)
Here, IM3ref: IM3 when modulated with OMIref
OMIref: Reference OMI, for example 0.2

ＣＮＲ＝［（ＯＭＩ）2 （η・Ｐr ）2 ／２］／｛［ＲＩＮ・（η・Ｐr ）2 ＋２ｑηＰr ＋（Ｉｎ）2 ］・ＢＷ｝ …（３）
ここで、ＲＩＮ ：相対強度雑音（Ｒｅｌａｔｉｖｅ Ｉｎｔｅｎｓｉｔｙ Ｎｏｉｓｅ）
η ：フォトダイオード（ＰＤ）の受光感度効率
Ｐr ：平均受光レベル（例えば光ロスαならば、Ｐr ＝α・Ｐave）
ｑ ：電気素量１．６０×１０-19
Ｉn ：入力換算雑音電流密度
ＢＷ ：雑音帯域幅 CNR = [(OMI) 2 ( η · Pr) 2/2] / {[RIN · (η · Pr) 2 + 2qηPr + (In) 2] · BW} ... (3)
Here, RIN: Relative intensity noise
η: Photosensitive sensitivity efficiency of photodiode (PD)
Pr: Average light receiving level (for example, if light loss α, Pr = α · Pave)
q: Elementary electric quantity 1.60 × 10 −19
In: Input equivalent noise current density
BW: Noise bandwidth

Ｇopt ＝ＰRF_OUT−ＰRF
＝（ＺPD／２）（ＯＭＩ・η・Ｐr ）2 −（ＺLD／２）｛ＯＭＩ・（Ｉb−Ｉth）｝2 …（４）
ここで、ＺPD：ＰＤの負荷抵抗 Gopt = PRF_OUT−PRF
= (ZPD / 2) (OMI · η · Pr) 2 − (ZLD / 2) {OMI · (Ib−Ith)} 2 (4)
Where ZPD: PD load resistance

上記（２）式、（３）式、（４）式からＯＭＩ（即ち、ＬＤへの入力レベル）を大きくすればＣＮＲがよくなり、ＯＭＩを小さくすればＩＭ３がよくなることが分り、又ＯＭＩを決定するとＣＮＲ、ＩＭ３が一義的に決定される。本発明では、設置場所、設置環境に応じたＣＮＲ、ＩＭ３が得られる様にＯＭＩ値を変更可能としたものである。   From the above formulas (2), (3), and (4), it can be seen that increasing the OMI (that is, the input level to the LD) increases the CNR, and decreasing the OMI improves the IM3. Once determined, CNR and IM3 are uniquely determined. In the present invention, the OMI value can be changed so that CNR and IM3 corresponding to the installation location and installation environment can be obtained.

図１により本発明の第１の実施の形態について説明する。   A first embodiment of the present invention will be described with reference to FIG.

図１は光伝送装置の電気／光変換部１を示しており、該電気／光変換部１にはＲＦアンプ２を介して前記電気／光変換部１に電気信号が入力される様になっており、前記ＲＦアンプ２は前記電気／光変換部１に一定レベルの電気信号が出力される様に調整されている。   FIG. 1 shows an electrical / optical conversion unit 1 of an optical transmission apparatus. An electrical signal is input to the electrical / optical conversion unit 1 via an RF amplifier 2. The RF amplifier 2 is adjusted so that an electric signal of a certain level is output to the electric / optical converter 1.

該電気／光変換部１について説明する。   The electrical / optical converter 1 will be described.

該電気／光変換部１の入力端子３に入力された電気信号を増幅する第１増幅部４、レーザダイオード９の利得のバラツキを吸収するＯＭＩ調整手段である第１可変減衰部５、増幅部の利得のバラツキを吸収する第２可変減衰部６、電気信号を増幅する第２増幅部７、ノイズ等をカットしてレーザダイオードへの過入力を防止する検波回路８、電気信号に対応して発光する電気／光変換器であるレーザダイオード（ＬＤ）９が順次接続され、該レーザダイオード９には光伝送部、例えば光ファイバ１１が接続されている。前記レーザダイオード９は駆動中、ペルチェ素子等の冷却手段（図示せず）により所定温度に冷却されている。   A first amplifying unit 4 for amplifying an electric signal input to the input terminal 3 of the electric / optical converting unit 1; a first variable attenuating unit 5 which is an OMI adjusting means for absorbing variations in the gain of the laser diode 9; In response to the electric signal, the second variable attenuating unit 6 that absorbs the gain variation, the second amplifying unit 7 that amplifies the electric signal, the detection circuit 8 that cuts noise and prevents over-input to the laser diode A laser diode (LD) 9 which is an electric / optical converter that emits light is sequentially connected, and an optical transmission unit, for example, an optical fiber 11 is connected to the laser diode 9. The laser diode 9 is cooled to a predetermined temperature by a cooling means (not shown) such as a Peltier element during driving.

前記レーザダイオード９のバイアス電流Ｉｂを検出し、Ａ／Ｄ変換しバイアス検出信号Ｃｂを出力するバイアス電流検出部１２が設けられ、該バイアス電流検出部１２からのバイアス検出信号ＣｂはＣＰＵで代表される演算処理部１３に入力される様になっている。該演算処理部１３は前記バイアス電流検出部１２からの検出結果を基に前記第１可変減衰部５に対して制御信号ＣATを出力し、該制御信号ＣATはＤ／Ａ変換部１４を介して前記第１可変減衰部５に減衰量制御信号ＶATとして入力される様になっている。   A bias current detector 12 is provided for detecting a bias current Ib of the laser diode 9, A / D converting and outputting a bias detection signal Cb. The bias detection signal Cb from the bias current detector 12 is represented by a CPU. Are input to the arithmetic processing unit 13. The arithmetic processing unit 13 outputs a control signal CAT to the first variable attenuation unit 5 based on the detection result from the bias current detection unit 12, and the control signal CAT is passed through the D / A conversion unit 14. The first variable attenuator 5 is inputted as an attenuation control signal VAT.

又、前記電気／光変換部１は記憶部１５を具備しており、該記憶部１５には図２に示される様な制御データテーブル１６が格納されており、前記演算処理部１３は前記バイアス電流検出部１２からの信号に基づき前記制御データテーブル１６を参照して前記減衰量制御信号ＶATを出力する様になっている。   The electrical / optical conversion unit 1 includes a storage unit 15. The storage unit 15 stores a control data table 16 as shown in FIG. 2, and the arithmetic processing unit 13 stores the bias. The attenuation control signal VAT is output with reference to the control data table 16 based on the signal from the current detector 12.

該制御データテーブル１６は、ＯＭＩに対するバイアス電流Ｉｂと前記演算処理部１３に入力されるバイアス検出信号Ｃｂ、該演算処理部１３から出力される制御信号ＣATとの関連付けが設定されている。   In the control data table 16, the association between the bias current Ib for OMI, the bias detection signal Cb input to the arithmetic processing unit 13, and the control signal CAT output from the arithmetic processing unit 13 is set.

例えば、前記レーザダイオード９に入力される電気信号のレベルをＯＭＩ1 に設定した場合、ＯＭＩ1 に維持するには、バイアス電流Ｉｂ1 の時、バイアス検出信号Ｃｂ11、制御信号ＣAT11であり、バイアス電流Ｉｂ2 の場合は、バイアス検出信号Ｃｂ12、制御信号ＣAT12となる等である。   For example, when the level of the electric signal input to the laser diode 9 is set to OMI1, the bias detection signal Cb11 and the control signal CAT11 are used when the bias current Ib1 is used to maintain the OMI1. Are the bias detection signal Cb12, the control signal CAT12, and so on.

更に、図２に示す関係が得られる様に、バイアス電流Ｉｂに対する前記バイアス電流検出部１２への入力信号Ｖｂ、バイアス検出信号Ｃｂ、制御信号ＣAT、前記Ｄ／Ａ変換部１４からの減衰量制御信号ＶATとの関連付けが図３のデータテーブル２１に示される様に設定され、例えばバイアス電流Ｉｂ1 の時、入力信号Ｖｂ1 、バイアス検出信号Ｃｂ1 、制御信号ＣAT1 、減衰量制御信号ＶAT1 であり、その時の前記第１可変減衰部５の減衰量がＤAT1 となる等である。   Further, in order to obtain the relationship shown in FIG. 2, the input signal Vb to the bias current detector 12, the bias detection signal Cb, the control signal CAT, and the attenuation amount control from the D / A converter 14 with respect to the bias current Ib are obtained. The association with the signal VAT is set as shown in the data table 21 of FIG. 3. For example, when the bias current is Ib1, the input signal Vb1, the bias detection signal Cb1, the control signal CAT1, and the attenuation control signal VAT1. The amount of attenuation of the first variable attenuation unit 5 is DAT1.

又、前記演算処理部１３にはＯＭＩ設定部（図示せず）からＯＭＩ設定信号１７が入力される様になっており、前記ＯＭＩ設定部は設置場所、設置環境に応じ最適な前記ＯＭＩ設定信号１７を前記演算処理部１３に入力する。   Further, an OMI setting signal 17 is input to the arithmetic processing unit 13 from an OMI setting unit (not shown), and the OMI setting signal is the optimum OMI setting signal according to the installation location and installation environment. 17 is input to the arithmetic processing unit 13.

以下、前記電気／光変換部１に於いて、ＯＭＩを一定に制御する作用について説明する。   Hereinafter, the operation of controlling the OMI to be constant in the electrical / optical converter 1 will be described.

設置場所、設置環境に応じ最適な前記ＯＭＩ設定信号１７が前記ＯＭＩ設定部（図示せず）より前記演算処理部１３に入力される。該演算処理部１３は入力されたＯＭＩ設定信号１７に対応するＯＭＩ値、例えばＯＭＩ1 となる様に、前記第１可変減衰部５の減衰率を制御する。   The optimal OMI setting signal 17 according to the installation location and installation environment is input to the arithmetic processing unit 13 from the OMI setting unit (not shown). The arithmetic processing unit 13 controls the attenuation factor of the first variable attenuation unit 5 so that the OMI value corresponding to the input OMI setting signal 17 becomes, for example, OMI1.

前記レーザダイオード９のバイアス電流Ｉｂ2 が前記バイアス電流検出部１２によって検出され、Ａ／Ｄ変換されてバイアス検出信号Ｃｂ12として前記演算処理部１３に出力される。該演算処理部１３は、入力されたバイアス検出信号Ｃｂ12を基に前記制御データテーブル１６を参照して制御信号ＣAT12を出力する。該制御信号ＣAT12は前記Ｄ／Ａ変換部１４によってＤ／Ａ変換され、減衰量制御信号ＶAT12として前記第１可変減衰部５に入力され、前記レーザダイオード９に入力される電気信号が一定となる様に減衰量ＤAT12に調整される。   A bias current Ib2 of the laser diode 9 is detected by the bias current detection unit 12, A / D converted, and output to the arithmetic processing unit 13 as a bias detection signal Cb12. The arithmetic processing unit 13 refers to the control data table 16 based on the input bias detection signal Cb12 and outputs a control signal CAT12. The control signal CAT12 is D / A converted by the D / A converter 14 and input to the first variable attenuator 5 as an attenuation control signal VAT12, and the electric signal input to the laser diode 9 becomes constant. In this way, the attenuation is adjusted to DAT12.

又、前記バイアス電流検出部１２によって前記レーザダイオード９のバイアス電流Ｉｂ1 が検出された場合は、Ａ／Ｄ変換されてバイアス検出信号Ｃｂ11として前記演算処理部１３に出力される。該演算処理部１３は、入力されたバイアス検出信号Ｃｂ11を基に前記ＯＭＩ設定信号１７がＯＭＩ1 となる様に、前記制御データテーブル１６を参照して制御信号ＣAT11を出力する。   When the bias current detector 12 detects the bias current Ib1 of the laser diode 9, it is A / D converted and output to the arithmetic processor 13 as a bias detection signal Cb11. The arithmetic processing unit 13 outputs the control signal CAT11 with reference to the control data table 16 so that the OMI setting signal 17 becomes OMI1 based on the input bias detection signal Cb11.

該制御信号ＣAT11は前記Ｄ／Ａ変換部１４によってＤ／Ａ変換され、減衰量制御信号ＶAT11として前記第１可変減衰部５に入力され、前記レーザダイオード９に入力される電気信号が一定となる様に減衰量ＤAT11に調整される。減衰量ＤATが制御され、前記レーザダイオード９の利得のバラツキが吸収され、該レーザダイオード９に入力されるＯＭＩが設定値に保持される。   The control signal CAT11 is D / A converted by the D / A converter 14 and input to the first variable attenuator 5 as the attenuation control signal VAT11, and the electric signal input to the laser diode 9 becomes constant. In this way, the attenuation amount DAT11 is adjusted. The attenuation amount DAT is controlled, the variation in gain of the laser diode 9 is absorbed, and the OMI input to the laser diode 9 is held at a set value.

而して、外部信号によりＯＭＩ値をＣＰＵに入力することによって所望のＯＭＩ値が実現される。   Thus, a desired OMI value is realized by inputting the OMI value to the CPU by an external signal.

図４は、本発明の第２の実施の形態を示すものであり、図４中、図１中で示したものと同等のものには同符号を付してある。   FIG. 4 shows a second embodiment of the present invention. In FIG. 4, the same components as those shown in FIG. 1 are denoted by the same reference numerals.

該第２の実施の形態は、基本的には第１の実施の形態と同様な構成を有し、前記第１可変減衰部５の前段に第３可変減衰部１８が設けられる。前記演算処理部１３は前記第３可変減衰部１８にＤ／Ａ変換部２０を介して指令信号１９を発する。   The second embodiment basically has the same configuration as that of the first embodiment, and a third variable attenuation unit 18 is provided in the preceding stage of the first variable attenuation unit 5. The arithmetic processing unit 13 issues a command signal 19 to the third variable attenuation unit 18 via the D / A conversion unit 20.

前記演算処理部１３に前記ＯＭＩ設定信号１７が入力されると、前記演算処理部１３は前記第３可変減衰部１８に対し前記Ｄ／Ａ変換部２０を介して指令信号１９を発し、前記第３可変減衰部１８は出力信号が前記演算処理部１３からの前記指令信号１９に対応したＯＭＩとなる様な減衰率を設定する。   When the OMI setting signal 17 is input to the arithmetic processing unit 13, the arithmetic processing unit 13 issues a command signal 19 to the third variable attenuation unit 18 via the D / A conversion unit 20, and The three variable attenuation unit 18 sets an attenuation rate such that the output signal becomes an OMI corresponding to the command signal 19 from the arithmetic processing unit 13.

第２の実施の形態に於ける記憶部１５に格納される制御データテーブル１６は図５に示される。又、前記第１可変減衰部５は図３で示されるデータテーブル２１を有しており、このデータテーブルはＯＭＩ値によらず固定とする。   The control data table 16 stored in the storage unit 15 in the second embodiment is shown in FIG. The first variable attenuation unit 5 has a data table 21 shown in FIG. 3, and this data table is fixed regardless of the OMI value.

ＯＭＩ値（ＯＭＩ）がＯＭＩ1 の時、ＣＰＵ出力値（ＣOMIAT)がＣOMIAT1 とし、ＣOMIAT1は前記Ｄ／Ａ変換部２０にてＶOMIAT1に変換され（ＤＡＣの出力電圧値ＶOMIAT)、第３可変減衰部１８の減衰量（ＤOMIAT）がＤOMIAT1 に制御される。ＯＭＩ値は設置場所の各環境下に於いてユーザよりＯＭＩ設定部を介して任意に入力されることにより、各ＯＭＩ値に対応したＣＰＵ出力値が出て前記第３可変減衰部１８の減衰量が制御される。   When the OMI value (OMI) is OMI1, the CPU output value (COMIAT) is COMIAT1, and COMIAT1 is converted to VOMIAT1 by the D / A converter 20 (DAC output voltage value VOMIAT). The amount of attenuation (DOMIAT) is controlled by DOMIAT1. The OMI value is arbitrarily input from the user via the OMI setting unit in each environment of the installation location, so that a CPU output value corresponding to each OMI value is output, and the attenuation amount of the third variable attenuation unit 18 Is controlled.

第２の実施の形態に於いては、前記第１可変減衰部５の減衰量を調整するとτ−ＬＤのバイアス値をモニタし、Ｅ／Ｏ変換された光変調度が一定になる様に利得を制御し、前記第３可変減衰部１８では光変調度を変更させる場合に光変調度に対応させ減衰率を変更することで利得を可変させる。従って、第２の実施の形態ではＬＤの光変調度を一定にする調整と、光変調度を変更する調整とを個別に行えるので、ＣＰＵの持つデータテーブルが簡素化されると共に調整が簡略化し、安定する。又、第１可変減衰部５と第３可変減衰部１８の２つで光変調度を調整することになるので、光変調可変の幅が大きくなる。   In the second embodiment, when the attenuation amount of the first variable attenuating unit 5 is adjusted, the bias value of τ-LD is monitored, and the gain is set so that the E / O converted light modulation degree becomes constant. The third variable attenuator 18 changes the gain by changing the attenuation factor corresponding to the optical modulation factor when the optical modulation factor is changed. Therefore, in the second embodiment, the adjustment for making the optical modulation degree of the LD constant and the adjustment for changing the optical modulation degree can be performed separately, so that the data table of the CPU is simplified and the adjustment is simplified. ,Stabilize. Further, since the light modulation degree is adjusted by the first variable attenuating unit 5 and the third variable attenuating unit 18, the width of the light modulation variable is increased.

以上説明した様に、本発明によれば電気／光変換部１に於いてＬＤバイアス値をモニタし、そのＬＤバイアス値によりＯＭＩが一定値になる様前記電気／光変換部１の利得を自動調整し、更に各環境下に於いてＯＭＩを変動させることを可能とし、光伝送装置の最適なＩＭ３・ＣＮＲを実現する。   As described above, according to the present invention, the LD bias value is monitored in the electric / optical converter 1, and the gain of the electric / optical converter 1 is automatically adjusted so that the OMI becomes a constant value according to the LD bias value. It is possible to adjust and further change the OMI in each environment, and realize the optimum IM3 · CNR of the optical transmission apparatus.

本発明の第１の実施の形態を示す概略構成図である。It is a schematic block diagram which shows the 1st Embodiment of this invention. 該第１の実施の形態で使用されるデータテーブルを示す図である。It is a figure which shows the data table used by this 1st Embodiment. 該第１の実施の形態に於ける各部位の信号の関係を示す図である。It is a figure which shows the relationship of the signal of each site | part in this 1st Embodiment. 本発明の第２の実施の形態を示す概略構成図である。It is a schematic block diagram which shows the 2nd Embodiment of this invention. 該第２の実施の形態で使用されるデータテーブルを示す図である。It is a figure which shows the data table used by this 2nd Embodiment.

符号の説明Explanation of symbols

１ 電気／光変換部
２ ＲＦアンプ
５ 第１可変減衰部
６ 第２可変減衰部
９ レーザダイオード
１３ 演算処理部
１４ Ｄ／Ａ変換部
１５ 記憶部
１６ 制御データテーブル
１７ ＯＭＩ設定信号 DESCRIPTION OF SYMBOLS 1 Electrical / optical conversion part 2 RF amplifier 5 1st variable attenuation part 6 2nd variable attenuation part 9 Laser diode 13 Arithmetic processing part 14 D / A conversion part 15 Memory | storage part 16 Control data table 17 OMI setting signal

Claims (1)

電気信号を光信号に変換するレーザダイオードと、該レーザダイオードに入力される信号の減衰量を調整する第１の光変調度調整手段及び第２の光変調度調整手段と、前記レーザダイオードのバイアス電流を検出しバイアス検出信号を出力するバイアス電流検出部と、設定された光変調度となる様に前記第１の光変調度調整手段及び第２の光変調度調整手段に制御信号を出力して減衰量を制御する演算処理部と、該演算処理部に光変調度の設定値を入力するＯＭＩ設定部と、前記設定値と前記バイアス検出信号と前記制御信号との関連付けが設定された制御データテーブルが格納された記憶部とを具備し、前記演算処理部は前記設定値に基づき前記制御データテーブルを参照して得られた前記制御信号により前記第１の光変調度調整手段の減衰量を制御すると共に、前記バイアス検出信号に基づき前記制御データテーブルを参照して得られた前記制御信号により前記第２の光変調度調整手段の減衰量を制御することを特徴とする光伝送装置。 A laser diode for converting an electrical signal into an optical signal, a first light modulation factor adjustment means and the second optical modulation index adjusting means for adjusting the attenuation amount of the signal input to the laser diode, the bias of the laser diode a bias current detecting unit for outputting a detection bias detection signal current, outputs a control signal to the first optical modulation index adjusting means and the second optical modulation adjusting means so as to be set to the optical modulation index an arithmetic processing unit which controls the attenuation amount is, the association of the OMI setting unit for inputting the optical modulation index set value to the arithmetic processing unit, the bias detection signal and the set value and the control signal is set and a storage unit in which the control data table is stored, reduction of the first optical modulation factor adjustment means the arithmetic processing unit by said control signal obtained by referring to the control data table based on the set value Controls the amount, the optical transmission apparatus characterized by controlling the attenuation amount of the reference by said control signal obtained by the second optical modulation index adjusting means said control data table based on the bias detection signal .
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Publication number Priority date Publication date Assignee Title
JPH04142127A (en) * 1990-10-02 1992-05-15 Canon Inc Light transmitter
JPH04192729A (en) * 1990-11-27 1992-07-10 Fujitsu Ltd Optical transmitter
JPH05190950A (en) * 1992-01-17 1993-07-30 Hitachi Cable Ltd Ld deterioration detecting circuit
JPH08265259A (en) * 1995-03-20 1996-10-11 Fujitsu Ltd Light amplification repeater
JP2000004203A (en) * 1998-06-17 2000-01-07 Hitachi Cable Ltd Optical transmitter
JP2000193854A (en) * 1998-12-25 2000-07-14 Toshiba Corp Optical analog transmitter

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH04142127A (en) * 1990-10-02 1992-05-15 Canon Inc Light transmitter
JPH04192729A (en) * 1990-11-27 1992-07-10 Fujitsu Ltd Optical transmitter
JPH05190950A (en) * 1992-01-17 1993-07-30 Hitachi Cable Ltd Ld deterioration detecting circuit
JPH08265259A (en) * 1995-03-20 1996-10-11 Fujitsu Ltd Light amplification repeater
JP2000004203A (en) * 1998-06-17 2000-01-07 Hitachi Cable Ltd Optical transmitter
JP2000193854A (en) * 1998-12-25 2000-07-14 Toshiba Corp Optical analog transmitter

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