JP2013207589A - Optical transmission device and optical transmission method - Google Patents

Optical transmission device and optical transmission method Download PDF

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JP2013207589A
JP2013207589A JP2012074918A JP2012074918A JP2013207589A JP 2013207589 A JP2013207589 A JP 2013207589A JP 2012074918 A JP2012074918 A JP 2012074918A JP 2012074918 A JP2012074918 A JP 2012074918A JP 2013207589 A JP2013207589 A JP 2013207589A
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JP6102073B2 (en
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Takehiro Nakano
雄大 中野
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NEC Corp
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Abstract

PROBLEM TO BE SOLVED: To restrain the fluctuation of a modulation state in an optical transmitter operated on an actual transmission line which is caused by temperature or other environmental conditions or degradation of components due to the lapse of time, thereby restraining degradation in signal quality.SOLUTION: An optical transmission device comprises: an optical signal source which generates an optical signal based on any modulation method; a drive clock source which outputs a drive clock at the same frequency as the repetition frequency of the optical signal; a phase modulator which adds phase modulation to the optical signal from the optical signal source by using the drive clock; an optical separator which branches output light from the phase modulator into a transmission path and a monitor path; optical branch means which branches monitor light from the optical separator into one or more wavelength bands by filtering; optical detection means which receives transmitted light in wavelength bands filtered by the optical branch means; a phase adjustment unit which adjusts the phase of the drive clock; an amplitude adjustment unit which adjusts the amplitude of the drive clock; and control means which controls the phase adjustment unit and the amplitude adjustment unit so that an optimum prechirp is added.

Description

本発明は、光送信装置及び光送信方法に関し、特に非線形劣化要因が大きい場合に改善する光送信装置及び光送信方法に関する。   The present invention relates to an optical transmission device and an optical transmission method, and more particularly to an optical transmission device and an optical transmission method that are improved when a nonlinear deterioration factor is large.

近年のネットワーク利用の急激な増加により、光ファイバを用いたネットワークのより一層の大容量化の要求が高まっている。光ファイバ伝送において、プリチャープ技術は非線形劣化など伝送特性を改善させる技術として効果があり、実伝送システムに適用する送信機として安定的に動作する制御方法の実現が望まれている。   Due to the rapid increase in network usage in recent years, there is an increasing demand for a further increase in capacity of a network using optical fibers. In optical fiber transmission, the pre-chirp technique is effective as a technique for improving transmission characteristics such as nonlinear degradation, and it is desired to realize a control method that stably operates as a transmitter applied to an actual transmission system.

光ファイバ伝送において、伝送特性を改善させる技術として、特許文献１にあるように、強度変調された光信号に対して分散予等化を施し光信号の送信を行う提案がある。本文献の特徴は、分散予等化を施し光信号の送信を行うことである。   As a technique for improving transmission characteristics in optical fiber transmission, there is a proposal to perform dispersion pre-equalization on an intensity-modulated optical signal and transmit the optical signal as disclosed in Patent Document 1. The feature of this document is that optical signal transmission is performed by performing dispersion pre-equalization.

また、特許文献２には、波長ずれ量からチャーピングの符号及びチャープ量を検出し、適切なチャープ設定を可能とする装置が提案されている。   Further, Patent Document 2 proposes an apparatus that detects a chirping code and a chirp amount from a wavelength shift amount and enables an appropriate chirp setting.

特許２８８５６０３号公報Japanese Patent No. 2885603 特開２００４−８０３０５号公報JP 2004-80305 A

実伝送路にて運用される光送信機においては、温度をはじめとする環境条件、部品の経年劣化などの要因により、変調状態が変動して、信号品質が劣化するのでこれを抑える設計が必要である。   Optical transmitters operated on actual transmission lines need to be designed to suppress this because signal quality deteriorates due to fluctuations in the modulation state due to environmental conditions such as temperature and aging deterioration of parts. It is.

特許文献１では、ＮＲＺ（ノン・リターン・トウ・ゼロ）や、ＲＺ（リターン・トウ・ゼロ）信号にのみ、信号分散予等化を施しているが、他の信号については言及していない。   In Patent Document 1, signal dispersion pre-equalization is performed only on NRZ (non-return toe-zero) and RZ (return-to-zero) signals, but other signals are not mentioned.

特許文献２では、光信号の立ち上がり、立ち下がり部分での波長ずれを検出し、チャーピングの符号及びチャープ量を検出している。   In Patent Document 2, the wavelength shift at the rising and falling portions of the optical signal is detected, and the chirping code and the chirp amount are detected.

本発明の目的は、簡単な構成にて変調度または駆動クロックの位相ズレを自律補正して、安定なプリチャープ変調をする光送信機及び光送信方法を提供することにある。   An object of the present invention is to provide an optical transmitter and an optical transmission method that perform stable pre-chirp modulation by autonomously correcting a modulation degree or a phase shift of a driving clock with a simple configuration.

上記課題を解決するために、本発明の光送信装置は、任意の変調方式の光信号を発生する光信号源と、光信号の繰り返し周波数と同じ周波数の駆動クロックを発出する駆動用クロック源と、駆動クロックを用いて光信号源からの光信号に位相変調を付加する位相変調器と、位相変調器からの出力光を送信用経路とモニタ用経路に分岐する光分波器と、光分波器からのモニタ用光を1つ以上の波長帯域にフィルタリングする光分岐手段と、光分岐手段にてフィルタリングされた波長帯域の透過光を受光する光検出手段と、駆動クロックの位相を調整する位相調整部と、駆動クロックの振幅を調整する振幅調整部と、最適なプリチャープを付加するよう位相調整部と振幅調整部を調整制御する制御手段と、を備えている。   In order to solve the above-described problems, an optical transmission device of the present invention includes an optical signal source that generates an optical signal of an arbitrary modulation method, a driving clock source that generates a driving clock having the same frequency as the repetition frequency of the optical signal, A phase modulator that adds phase modulation to an optical signal from an optical signal source using a drive clock, an optical demultiplexer that branches output light from the phase modulator into a transmission path and a monitoring path, Optical branching means for filtering monitoring light from the wave filter to one or more wavelength bands, optical detection means for receiving transmitted light in the wavelength band filtered by the optical branching means, and adjusting the phase of the drive clock A phase adjustment unit; an amplitude adjustment unit that adjusts the amplitude of the drive clock; and a control unit that adjusts and controls the phase adjustment unit and the amplitude adjustment unit to add an optimal pre-chirp.

上記課題を解決するために、本発明の光送信方法は、最適なプリチャープを付加するよう位相調整部と振幅調整部を調整制御する制御手段を備えた光送信装置の光送信方法であって、制御手段は、振幅調整部に対して駆動クロックの振幅を調整するよう制御することを特徴とする。   In order to solve the above problems, an optical transmission method of the present invention is an optical transmission method of an optical transmission device including a control unit that adjusts and controls a phase adjustment unit and an amplitude adjustment unit so as to add an optimal pre-chirp, The control means controls the amplitude adjusting unit to adjust the amplitude of the drive clock.

上記課題を解決するために、本発明の光送信方法は、最適なプリチャープを付加するよう位相調整部と振幅調整部を調整制御する制御手段を備えた光送信装置の光送信方法であって、光検出手段のフィルタの受光パワーの相違する条件が位相ズレ要因の場合は、位相調整部に対して駆動クロックの位相を調整するよう制御し、次に、メモリ部に格納してある運用設置時のプリチャープ量を示す受光レベルと、調整時の受光レベルとを比較し、両者が同じになるように振幅調整部を調整することを特徴とする。   In order to solve the above problems, an optical transmission method of the present invention is an optical transmission method of an optical transmission device including a control unit that adjusts and controls a phase adjustment unit and an amplitude adjustment unit so as to add an optimal pre-chirp, When the condition that the received light power of the filter of the light detection means is different is a phase shift factor, the phase adjustment unit is controlled to adjust the phase of the drive clock, and then the operation setting stored in the memory unit The light receiving level indicating the amount of pre-chirp is compared with the light receiving level at the time of adjustment, and the amplitude adjusting unit is adjusted so that both are the same.

上記課題を解決するために、本発明の光送信方法は、最適なプリチャープを付加するよう位相調整部と前記振幅調整部を調整制御する制御手段を備えた光送信装置の光送信方法であって、制御手段は、位相調整部に対して、光検出手段のフィルタ出力をメモリ部に記憶された初期値と同じになるように駆動クロックの位相を調整するよう制御することを特徴とする。   In order to solve the above problems, an optical transmission method of the present invention is an optical transmission method of an optical transmission device including a control unit for adjusting and controlling a phase adjustment unit and the amplitude adjustment unit so as to add an optimal pre-chirp. The control unit controls the phase adjustment unit to adjust the phase of the drive clock so that the filter output of the light detection unit becomes the same as the initial value stored in the memory unit.

本発明によれば、高い信号品質が求められる光伝送装置及び光送信方法にて、簡単な構成で自律動作し、信号品質が安定したプリチャープ変調信号を伝送することが可能である。   According to the present invention, it is possible to transmit a pre-chirp modulated signal with a stable signal quality, autonomously operating with a simple configuration, in an optical transmission device and an optical transmission method that require high signal quality.

本発明の第１の実施形態における基本構成を示すブロック図である。It is a block diagram which shows the basic composition in the 1st Embodiment of this invention. 本発明の第１の実施形態における位相変調器の出力光スペクトラムのピークと波長の関係を示すグラフである。It is a graph which shows the relationship between the peak of the output light spectrum of the phase modulator in the 1st Embodiment of this invention, and a wavelength. 本発明の第１の実施形態におけるフォトダイオードの検出強度と駆動クロック振幅の関係を示した図である。It is the figure which showed the relationship between the detection intensity of the photodiode in the 1st Embodiment of this invention, and a drive clock amplitude. 本発明の第１の実施形態における駆動クロックの位相ずれの状態を示した図である。It is the figure which showed the state of the phase shift of the drive clock in the 1st Embodiment of this invention. 本発明の第１の実施形態におけるフォトダイオードの検出強度と駆動クロックの位相ずれ量の関係を示した図である。It is the figure which showed the relationship between the detection strength of the photodiode in the 1st Embodiment of this invention, and the phase shift amount of a drive clock. 本発明の第１の実施形態における調整方法を示すフローチャートである。It is a flowchart which shows the adjustment method in the 1st Embodiment of this invention. 本発明の第２の実施形態における基本構成を示すブロック図である。It is a block diagram which shows the basic composition in the 2nd Embodiment of this invention. 本発明の第２の実施形態における調整方法を示すフローチャートである。It is a flowchart which shows the adjustment method in the 2nd Embodiment of this invention. 本発明の第３の実施形態における基本構成を示すブロック図である。It is a block diagram which shows the basic composition in the 3rd Embodiment of this invention. 本発明の第３の実施形態における調整方法を示すフローチャートである。It is a flowchart which shows the adjustment method in the 3rd Embodiment of this invention.

以下、本発明の実施形態について図面を参照して詳細に説明する。   Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

（第１の実施形態）
図１は、本発明の第１の実施形態における基本構成を示すブロック図である。本実施形態は、駆動クロックの振幅、位相をともに自律安定制御できる構成例である。 (First embodiment)
FIG. 1 is a block diagram showing a basic configuration in the first embodiment of the present invention. This embodiment is a configuration example in which both the amplitude and phase of the drive clock can be controlled autonomously.

本実施形態の光送信装置は、ＮＲＺ、ＲＺ、ＰＳＫ（フェーズ・シフト・キーイング）信号ほか任意の変調方式にて光信号を発出する光信号源１０、駆動クロックを用いて光信号源からの光信号に位相変調を付加する位相変調器１４、光信号の繰り返し周波数と同周波数の駆動クロックを発出する駆動用クロック源１１、制御信号Ｙにて駆動クロックの位相を調整する位相調整部１２、制御信号Ｘにて駆動クロックの振幅を調整する振幅調整部１３を備えている。更に、本実施形態の光送信装置は、位相変調器１４からの出力光を送信用経路とモニタ用経路に分岐する光分波器１５、光分波器１５からのモニタ用光を波長帯域Ａ、Ｂ、Ｃに（Ａ、Ｂ、Ｃは、帯域は同じで、Ａを中心波長として、Ｂ及びＣは、上下に等間隔離れた波長）それぞれ狭帯域にフィルタリングするフィルタＦＩＬ-Ａ、ＦＩＬ-Ｂ、ＦＩＬ-Ｃを備えた光分岐手段１６を備えている。更に、本実施形態の光送信装置は、光分岐手段１６にてフィルタリングされた波長帯域Ａ、Ｂ、Ｃの透過光をそれぞれ受光するフォトダイオードＰＤ-Ａ、ＰＤ−Ｂ、ＰＤ−Ｃを備えた光検出手段１７を備えている。更に、本実施形態の光送信装置は、光検出手段１７からの結果に基づいて、制御信号Ｘ、制御信号Ｙを出力する制御手段１８を備えている。制御手段１８は、光検出手段１７からの結果を記憶するメモリ部１９を備えている。   The optical transmission apparatus according to the present embodiment includes an optical signal source 10 that emits an optical signal by an arbitrary modulation method, such as an NRZ, RZ, and PSK (phase shift keying) signal, and an optical signal from an optical signal source using a drive clock. A phase modulator 14 for adding phase modulation to the signal, a driving clock source 11 for generating a driving clock having the same frequency as the repetition frequency of the optical signal, a phase adjusting unit 12 for adjusting the phase of the driving clock by the control signal Y, and control An amplitude adjustment unit 13 that adjusts the amplitude of the drive clock by the signal X is provided. Furthermore, the optical transmission device of this embodiment includes an optical demultiplexer 15 that branches the output light from the phase modulator 14 into a transmission path and a monitoring path, and the monitoring light from the optical demultiplexer 15 in the wavelength band A. , B, and C (A, B, and C have the same band, A is a central wavelength, and B and C are wavelengths that are spaced apart at equal intervals in the vertical direction), respectively, filters FIL-A, FIL- B, an optical branching means 16 having FIL-C is provided. Furthermore, the optical transmission apparatus of the present embodiment includes photodiodes PD-A, PD-B, and PD-C that respectively receive the transmitted light in the wavelength bands A, B, and C filtered by the optical branching unit 16. Photodetection means 17 is provided. Further, the optical transmission apparatus of the present embodiment includes a control unit 18 that outputs a control signal X and a control signal Y based on the result from the light detection unit 17. The control unit 18 includes a memory unit 19 that stores the result from the light detection unit 17.

光信号源１０からの任意周波数の光信号に、位相変調器１４を用いてプリチャープを付加し、光分波器１５にて伝送路への送信用経路とモニタ用経路に分岐する。分岐した光は、光分岐手段１６に内蔵された狭帯域フィルタにてフィルタリングされ、光検出手段１７で受信される。プリチャープを付加するために、駆動用クロック源１１から出力され、振幅調整部１３と位相調整部１２にて振幅と位相を調整された、駆動クロックを用いる。   Pre-chirp is added to the optical signal of an arbitrary frequency from the optical signal source 10 by using the phase modulator 14, and the optical demultiplexer 15 branches the transmission path to the transmission path and the monitoring path. The branched light is filtered by a narrow band filter built in the light branching means 16 and received by the light detecting means 17. In order to add pre-chirp, a drive clock output from the drive clock source 11 and adjusted in amplitude and phase by the amplitude adjustment unit 13 and the phase adjustment unit 12 is used.

次に、第１の実施形態の動作について、図２乃至図６を用いて説明する。   Next, the operation of the first embodiment will be described with reference to FIGS.

位相変調は、光信号源の繰返し周波数と同期したクロックを駆動するものとする。駆動クロックの振幅が高いほど、位相変調器１４の出力光スペクトラムは広がり、スペクトラムピークは下がる特性となる。図２は、位相変調器１４の出力光スペクトラムのピークと波長の関係を示すグラフである。縦軸は、出力光スペクトラムのレベル、横軸は、スペクトラムの波長である。図２のように、出力光スペクトラムが広がると、スペクトラムピークは、下がる特性となる。   In the phase modulation, a clock synchronized with the repetition frequency of the optical signal source is driven. The higher the drive clock amplitude, the wider the output light spectrum of the phase modulator 14 and the lower the spectrum peak. FIG. 2 is a graph showing the relationship between the peak of the output light spectrum of the phase modulator 14 and the wavelength. The vertical axis represents the level of the output light spectrum, and the horizontal axis represents the wavelength of the spectrum. As shown in FIG. 2, when the output light spectrum is widened, the spectrum peak has a characteristic of decreasing.

また、駆動クロックの位相が変動すると送信スペクトラムの形状は図４のように変化してしまう。図４は、図２の透過帯域を持つフィルタに対して、駆動クロックの位相ズレの状態を示した図である。図４の縦軸は、出力光スペクトラムのレベル、横軸は、スペクトラムの波長である。駆動クロックの振幅、位相とも環境条件などの要因により変動してしまう場合、プリチャープ後の変調度やスペクトラム形状が変動してしまい一定の信号品質が得られない。そこで、ＰＤ−Ａ、Ｂ、Ｃの検出パワーの結果を元に制御信号Ｘ、Ｙを制御し、プリチャープの変調度の安定化を図る。   Further, when the phase of the drive clock varies, the shape of the transmission spectrum changes as shown in FIG. FIG. 4 is a diagram showing a state of phase shift of the drive clock with respect to the filter having the transmission band of FIG. The vertical axis in FIG. 4 is the level of the output light spectrum, and the horizontal axis is the wavelength of the spectrum. When the amplitude and phase of the drive clock fluctuate due to factors such as environmental conditions, the degree of modulation after pre-chirping and the spectrum shape fluctuate, and a constant signal quality cannot be obtained. Therefore, control signals X and Y are controlled based on the detection power results of PD-A, B, and C to stabilize the pre-chirp modulation degree.

制御動作の詳細について説明をする。まず、駆動クロック振幅の変動があった場合、図２のようなスペクトラムの変動となる。同図Ｌ、Ｍ、Ｎの順で駆動クロック振幅が高くなっており、スペクトラムが広がり、中心波長のピークが下がる特性となる。このとき、ＰＤ−Ａ、Ｂ、Ｃにて受光する光パワーは、図３のように変化するものとする。図３は、駆動クロック振幅とＰＤの検出強度の関係を示すグラフである。ＰＤ−Ａは、スペクトラム中心波長をモニタしており、駆動クロック振幅が大きくなるほどＰＤ−Ａの入力レベルは低下する。この例では単純化するために、ＰＤ−Ａの受光パワーを線形グラフとして表しているが、その線形性は特に問わないものとする。一方ＦＩＬ−Ｂ、Ｃは、中心から任意間隔にて正側・負側に同間隔離して配置しており、駆動クロック振幅量に問わず、同じ受光パワーを検出する。図３では、図２の駆動クロック振幅が、Ｌ、Ｍ、Ｎの順に大きくなるとすると、ＰＤ−Ｂ、Ｃの受光パワーの駆動クロック振幅依存性のカーブは、Ｍの付近で頂点になるようなカーブを示す。図３に示すＰＤ−Ｂ、Ｃの受光パワーの駆動クロック振幅依存性のカーブは一例であり、当特性はピーク波長からの距離により形状は異なる。   Details of the control operation will be described. First, when the drive clock amplitude varies, the spectrum varies as shown in FIG. The drive clock amplitude increases in the order of L, M, and N in the same figure, and the spectrum spreads and the peak of the center wavelength decreases. At this time, the optical power received by PD-A, B, and C is assumed to change as shown in FIG. FIG. 3 is a graph showing the relationship between drive clock amplitude and PD detection intensity. PD-A monitors the spectrum center wavelength, and the input level of PD-A decreases as the drive clock amplitude increases. In this example, for simplification, the light receiving power of the PD-A is represented as a linear graph, but the linearity is not particularly limited. On the other hand, FIL-B and C are arranged on the positive side and the negative side at an arbitrary interval from the center and are separated from each other, and detect the same received light power regardless of the drive clock amplitude. In FIG. 3, assuming that the drive clock amplitude in FIG. 2 increases in the order of L, M, and N, the curve of the drive clock amplitude dependency of the received light power of PD-B and C becomes apex in the vicinity of M. Shows the curve. The curve of the drive clock amplitude dependency of the received light power of PD-B and C shown in FIG. 3 is an example, and the shape of this characteristic varies depending on the distance from the peak wavelength.

次に、駆動クロックの位相ズレがおきた場合のスペクトラム変動について、図４を用いて説明する。図４は、正負片側に駆動クロック位相がずれた場合のスペクトラム例を記載しており、Ｏ、Ｐ、Ｑの順で同一方向のズレ量が大きいものとなっている。逆側のズレ量については同図の中心波長を軸に当Ｐ、Ｑを反転した特性となる。このときのＰＤ−Ａ、Ｂ、Ｃでの位相ズレ量と受光パワーの関係を図５に示す。図５の縦軸は、受光パワーの検出強度で横軸は、駆動クロックの位相ずれ量を示している。図５上でＰＤ−Ａでは、位相ズレ量０での受光パワーをピークとし、正負問わずズレ量が大きいほど受光パワーが下がる。一方、ＰＤ−Ｂ、Ｃはズレ量０を軸に対称の受光パワーのカーブとなる。ＰＤ−Ｂ、Ｃ受光パワーのカーブの形状は、ＦＩＬ−Ｂ、Ｃが中心波長から離れる距離やフィルタ幅による。   Next, spectrum fluctuation when the drive clock phase shift occurs will be described with reference to FIG. FIG. 4 shows an example of a spectrum when the drive clock phase is shifted to the positive or negative side, and the amount of deviation in the same direction is large in the order of O, P, and Q. The shift amount on the opposite side has a characteristic in which P and Q are inverted with the center wavelength in the figure as an axis. FIG. 5 shows the relationship between the amount of phase shift and the received light power at PD-A, B, and C at this time. The vertical axis in FIG. 5 represents the detected intensity of the received light power, and the horizontal axis represents the phase shift amount of the drive clock. In FIG. 5, in PD-A, the received light power at a phase shift amount of 0 is a peak, and the received light power decreases as the shift amount increases regardless of positive or negative. On the other hand, PD-B and C are symmetrical light-receiving power curves with the amount of misalignment being zero. The shape of the PD-B, C light reception power curve depends on the distance at which FIL-B, C is away from the center wavelength and the filter width.

駆動クロックの振幅、位相ともに設定値からズレが生じている場合を例に、プリチャープ付加状態を安定制御するための方法例を図６のフローチャートにしたがって説明する。上記で説明した駆動クロックの振幅量、位相変動量、ＦＩＬ−Ａ、Ｂ、Ｃの受光パワーの関係性から、ＰＤ−ＢとＰＤ−Ｃの受光パワーが相違する条件は位相ズレ要因のみである。このため、制御としてまずＰＤ−Ｂ、Ｃ、それぞれの受光パワーを比較し(ステップ１０１)、同一となるよう制御信号Ｙを用いて、駆動クロックの位相を調整する(ステップ１０２、１０３)。次に、駆動クロック振幅の調整をおこなう。ＰＤ−ＢとＰＤ−Ｃの受光パワーを同一レベルに調整した後は、ＰＤ−Ａの受光レベルは、駆動クロック振幅量のみで決まるため、運用設置時の受光レベルをＰＤ−Ａｓに設定し、メモリ部１９に格納してある運用設置時のプリチャープ量ＰＤ−Ａｓと、ＰＤ−Ａの受光レベルとを比較し（ステップ１０４、１０５）、両者が同じになるように制御信号Ｘを用いて振幅調整すれば(ステップ１０６)、プリチャープ量を補正できる。   An example of a method for stably controlling the pre-chirp addition state will be described with reference to the flowchart of FIG. Due to the relationship between the amplitude amount of the drive clock, the amount of phase fluctuation, and the received light powers of FIL-A, B, and C described above, the only condition for the difference in the received light power of PD-B and PD-C is the phase shift factor. . Therefore, as control, first, the received light powers of PD-B and C are compared (step 101), and the phase of the drive clock is adjusted using the control signal Y so as to be the same (steps 102 and 103). Next, the drive clock amplitude is adjusted. After adjusting the light reception power of PD-B and PD-C to the same level, the light reception level of PD-A is determined only by the drive clock amplitude, so the light reception level at the time of operation installation is set to PD-As, The pre-chirp amount PD-As at the time of operation and installation stored in the memory unit 19 is compared with the light reception level of the PD-A (steps 104 and 105), and the amplitude is obtained using the control signal X so that both are the same. If adjusted (step 106), the pre-chirp amount can be corrected.

また、制御手段内のメモリ部を用いる代わりに、運用プリチャープ量ＰＤ−Ａｓに相当する初期固定値とＰＤ−Ａを比較し、両者が同じになるよう制御信号Ｘを出力する比較回路を用いても、プリチャープ量を補正することができる。   Further, instead of using the memory unit in the control means, a comparison circuit that compares the initial fixed value corresponding to the operation pre-chirp amount PD-As and PD-A and outputs the control signal X so that both are the same is used. Also, the pre-chirp amount can be corrected.

このように、簡単な構成で、変調度または駆動クロックの位相ズレを自律補正して、安定なプリチャープ量を補正可能である。
（第２の実施形態）
図７は、本発明の第２の実施形態における基本構成を示すブロック図である。 Thus, with a simple configuration, it is possible to correct a stable pre-chirp amount by autonomously correcting the degree of modulation or the phase shift of the drive clock.
(Second Embodiment)
FIG. 7 is a block diagram showing a basic configuration in the second embodiment of the present invention.

本実施形態の光送信装置は、ＮＲＺ、ＲＺ、ＰＳＫ信号ほか任意の変調方式にて光信号を発出する光信号源１０、駆動クロックを用いて光信号源からの光信号に位相変調を付加する位相変調器１４、光信号の繰り返し周波数と同周波数の駆動クロックを発出する駆動用クロック源１１、制御信号Ｙにて駆動クロックの位相を調整する位相調整部１２、制御信号Ｘにて駆動クロックの振幅を調整する振幅調整部１３を備えている。更に、本実施形態の光送信装置は、位相変調器１４からの出力光を送信用経路とモニタ用経路に分岐する光分波器１５、光分波器１５からのモニタ用光を波長帯域Ａ、Ｂ、Ｃに（Ａ、Ｂ、Ｃは、帯域は同じで、Ａを中心波長として、Ｂ及びＣは、上下に等間隔離れた波長）それぞれ狭帯域にフィルタリングするフィルタＦＩＬ-Ａ、ＦＩＬ-Ｂ、ＦＩＬ-Ｃを備えた光分岐手段１６を備えている。更に、本実施形態の光送信装置は、光分岐手段１６にてフィルタリングされた波長帯域Ａ、Ｂ、Ｃの透過光をそれぞれ受光するフォトダイオードＰＤ-Ａ、ＰＤ−Ｂ、ＰＤ−Ｃを備えた光検出手段１７を備えている。更に、本実施形態の光送信装置は、光検出手段１７からの結果に基づいて、制御信号Ｘ、制御信号Ｙを出力する制御手段２０を備えている。制御手段２０は、光検出手段１７からの結果を記憶するメモリ部２１を備えている。   The optical transmission apparatus according to the present embodiment adds phase modulation to an optical signal from an optical signal source using an optical signal source 10 that emits an optical signal by an arbitrary modulation method other than NRZ, RZ, and PSK signals, and a driving clock. A phase modulator 14; a driving clock source 11 that emits a driving clock having the same frequency as the optical signal repetition frequency; a phase adjustment unit 12 that adjusts the phase of the driving clock by the control signal Y; An amplitude adjustment unit 13 that adjusts the amplitude is provided. Furthermore, the optical transmission device of this embodiment includes an optical demultiplexer 15 that branches the output light from the phase modulator 14 into a transmission path and a monitoring path, and the monitoring light from the optical demultiplexer 15 in the wavelength band A. , B, and C (A, B, and C have the same band, A is a central wavelength, and B and C are wavelengths that are spaced apart at equal intervals in the vertical direction), respectively, filters FIL-A, FIL- B, an optical branching means 16 having FIL-C is provided. Furthermore, the optical transmission apparatus of the present embodiment includes photodiodes PD-A, PD-B, and PD-C that respectively receive the transmitted light in the wavelength bands A, B, and C filtered by the optical branching unit 16. Photodetection means 17 is provided. Furthermore, the optical transmission apparatus according to the present embodiment includes a control unit 20 that outputs a control signal X and a control signal Y based on a result from the light detection unit 17. The control unit 20 includes a memory unit 21 that stores the result from the light detection unit 17.

光信号源１０からの任意周波数の光信号に、位相変調器１４を用いてプリチャープを付加し、光分波器１５にて伝送路への送信用経路とモニタ用経路に分岐する。分岐した光は、光分岐手段１６に内蔵された狭帯域フィルタにてフィルタリングされ、光検出手段１７で受信される。プリチャープを付加するために、振幅調整部１３と位相調整部１２にて振幅と位相を調整した、駆動用クロック源１１から出力された駆動クロックを用いる。   Pre-chirp is added to the optical signal of an arbitrary frequency from the optical signal source 10 by using the phase modulator 14, and the optical demultiplexer 15 branches the transmission path to the transmission path and the monitoring path. The branched light is filtered by a narrow band filter built in the light branching means 16 and received by the light detecting means 17. In order to add the pre-chirp, the drive clock output from the drive clock source 11 whose amplitude and phase are adjusted by the amplitude adjusting unit 13 and the phase adjusting unit 12 is used.

次に、第２の実施形態の動作について、図８を用いて説明する。図８は、本発明の第２の実施形態における調整方法を示すフローチャートである。   Next, the operation of the second embodiment will be described with reference to FIG. FIG. 8 is a flowchart showing an adjustment method according to the second embodiment of the present invention.

運用設置時のプリチャープ設定時のＰＤ−Ｂ、ＰＤ-Ｃの受光レベルの絶対値を（Ｌｂ０、Ｌｃ０）とし、制御手段２０に備えられているメモリ２１に記憶しておく。そして、光検出手段１７より入力した、現在のＰＤ−Ｂ、ＰＤ-Ｃの受光レベルの絶対値を（Ｌｂ１、Ｌｃ１）とする。まず、プリチャープ設定時のＰＤ−Ｂ、ＰＤ-Ｃの受光レベルの絶対値（Ｌｂ０、Ｌｃ０）を現在のＰＤ−Ｂ、ＰＤ-Ｃの受光レベルの絶対値（Ｌｂ１、Ｌｃ１）と比較する(ステップ２０１)。次に、Ｌｂ０＝Ｌｂ１、Ｌｃ０＝Ｌｃ１となるように制御信号Ｙを調整する（ステップ２０２）。ここでは、第１の実施形態の駆動クロック振幅の調整で、ＰＤ−ＢとＰＤ−Ｃの受光パワーを同一レベルに調整する代わりに、受光レベルの絶対値をプリチャープ設定時と現在の値とを合わせている。   The absolute values of the received light levels of PD-B and PD-C at the time of pre-chirp setting at the time of operation installation are set as (Lb0, Lc0) and stored in the memory 21 provided in the control means 20. The absolute values of the light reception levels of the current PD-B and PD-C input from the light detection means 17 are (Lb1, Lc1). First, the absolute values (Lb0, Lc0) of the received light levels of PD-B and PD-C at the time of pre-chirp setting are compared with the absolute values (Lb1, Lc1) of the received light levels of the current PD-B and PD-C (Step 1). 201). Next, the control signal Y is adjusted so that Lb0 = Lb1 and Lc0 = Lc1 (step 202). Here, instead of adjusting the light reception power of PD-B and PD-C to the same level by adjusting the drive clock amplitude in the first embodiment, the absolute value of the light reception level is set to the current value when pre-chirping is set. It is matched.

そして、運用設置時のプリチャープ量ＰＤ−Ａｓと、ＰＤ−Ａの受光レベルとを比較し（ステップ２０３、２０４）、同じになるように制御信号Ｘを用いて振幅調整すれば(ステップ２０５)、プリチャープ量を補正できる。   Then, the pre-chirp amount PD-As at the time of operation installation is compared with the light reception level of PD-A (steps 203 and 204), and if the amplitude is adjusted using the control signal X so as to be the same (step 205), Pre-chirp amount can be corrected.

このように、第２の実施形態では、受光レベルの絶対値を用いて、変調度または駆動クロックの位相ズレを自律補正して、安定なプリチャープ量を補正可能としている。
（第３の実施形態）
図９は本発明の第３の実施形態における基本構成を示すブロック図である。 As described above, in the second embodiment, the absolute value of the light reception level is used to autonomously correct the modulation degree or the phase shift of the drive clock, thereby making it possible to correct the stable pre-chirp amount.
(Third embodiment)
FIG. 9 is a block diagram showing a basic configuration in the third embodiment of the present invention.

本実施形態の光送信装置は、ＮＲＺ、ＲＺ、ＰＳＫ信号ほか任意の変調方式にて光信号を発出する光信号源１０、駆動クロックを用いて光信号源からの光信号に位相変調を付加する位相変調器１４、光信号の繰り返し周波数と同周波数の駆動クロックを発出する駆動用クロック源１１、制御信号Ｙにて駆動クロックの位相を調整する位相調整部１２、制御信号Ｘにて駆動クロックの振幅を調整する振幅調整部１３を備えている。更に、本実施形態の光送信装置は、位相変調器１４からの出力光を送信用経路とモニタ用経路に分岐する光分波器１５、光分波器１５からのモニタ用光を波長帯域Ａ、Ｂ、Ｃに（Ａ、Ｂ、Ｃは、帯域は同じで、Ａを中心波長として、Ｂ及びＣは、上下に等間隔離れた波長）合わせて、それぞれ狭帯域にフィルタリングする可変フィルタＦＩＬ−Ｋを備えた光分岐手段２２を備えている。更に、本実施形態の光送信装置は、光分岐手段２２にてフィルタリングされた透過光を受光するフォトダイオードＰＤ−Ｋを備えた光検出手段２３を備えている。更に、本実施形態の光送信装置は、光検出手段２２からの結果に基づいて、制御信号Ｘ、制御信号Ｙを出力する制御手段２４を備えている。制御手段２４は、光検出手段２３からの結果を記憶するメモリ部２５を備えている。   The optical transmission apparatus according to the present embodiment adds phase modulation to an optical signal from an optical signal source using an optical signal source 10 that emits an optical signal by an arbitrary modulation method other than NRZ, RZ, and PSK signals, and a driving clock. A phase modulator 14; a driving clock source 11 that emits a driving clock having the same frequency as the optical signal repetition frequency; a phase adjustment unit 12 that adjusts the phase of the driving clock by the control signal Y; An amplitude adjustment unit 13 that adjusts the amplitude is provided. Furthermore, the optical transmission device of this embodiment includes an optical demultiplexer 15 that branches the output light from the phase modulator 14 into a transmission path and a monitoring path, and the monitoring light from the optical demultiplexer 15 in the wavelength band A. , B, and C (A, B, and C have the same band, A is the central wavelength, and B and C are wavelengths that are equally spaced apart from each other in the vertical direction), and are each filtered by a narrow filter FIL− An optical branching means 22 having K is provided. Furthermore, the optical transmission device of the present embodiment includes a light detection unit 23 including a photodiode PD-K that receives the transmitted light filtered by the light branching unit 22. Furthermore, the optical transmission apparatus according to the present embodiment includes a control unit 24 that outputs a control signal X and a control signal Y based on the result from the light detection unit 22. The control unit 24 includes a memory unit 25 that stores the result from the light detection unit 23.

光信号源１０からの任意周波数の光信号に、位相変調器１４を用いてプリチャープを付加し、光分波器１５にて伝送路への送信用経路とモニタ用経路に分岐する。分岐した光は、光分岐手段２２に内蔵された狭帯域フィルタにてフィルタリングされ、光検出手段２３で受信される。光検出手段２３の出力を一旦、制御手段２４の中のメモリ部２５に格納する。プリチャープを付加するためには、振幅調整部１３と位相調整部１２にて振幅と位相を調整した、駆動用クロック源１１から出力された駆動クロックを用いる。   Pre-chirp is added to the optical signal of an arbitrary frequency from the optical signal source 10 by using the phase modulator 14, and the optical demultiplexer 15 branches the transmission path to the transmission path and the monitoring path. The branched light is filtered by a narrow band filter built in the light branching means 22 and received by the light detecting means 23. The output of the light detection means 23 is temporarily stored in the memory unit 25 in the control means 24. In order to add the pre-chirp, the drive clock output from the drive clock source 11 whose amplitude and phase are adjusted by the amplitude adjusting unit 13 and the phase adjusting unit 12 is used.

次に、第３の実施形態の動作について、図１０を用いて説明する。図１０は、本発明の第３の実施形態における調整方法を示すフローチャートである。   Next, the operation of the third embodiment will be described with reference to FIG. FIG. 10 is a flowchart showing an adjustment method according to the third embodiment of the present invention.

この第３の実施形態の動作は、第１の実施形態と同じで、制御として、まず可変フィルタＦＩＬ−Ｋから、ＰＤ−Ｂ、ＰＤ−Ｃの部分を取り出す。そして、それぞれの受光パワーを比較し(ステップ３０１)、同一となるよう制御信号Ｙを用いて、駆動クロックの位相を調整する(ステップ３０２、３０３)。次に、駆動クロック振幅の調整をおこなう。ＰＤ−ＢとＰＤ−Ｃの受光パワーを同一レベルに調整した後は、ＰＤ−Ａの受光レベルは、駆動クロック振幅量のみで決まるため、運用設置時の受光レベルを（ＰＤ−Ａｓ）に設定し、メモリ部２５に格納してある運用設置時のプリチャープ量ＰＤ−Ａｓと、ＰＤ−Ａの受光レベルとを比較し（ステップ３０４、３０５）、両者が同じになるように制御信号Ｘを用いて振幅調整すれば(ステップ３０６)、プリチャープ量を補正できる。   The operation of the third embodiment is the same as that of the first embodiment. As a control, the PD-B and PD-C portions are first extracted from the variable filter FIL-K. Then, the received light powers are compared (step 301), and the phase of the drive clock is adjusted using the control signal Y so as to be the same (steps 302 and 303). Next, the drive clock amplitude is adjusted. After adjusting the light reception power of PD-B and PD-C to the same level, the light reception level of PD-A is determined only by the drive clock amplitude, so the light reception level at the time of operation installation is set to (PD-As). Then, the pre-chirp amount PD-As at the time of operation installation stored in the memory unit 25 is compared with the light reception level of the PD-A (steps 304 and 305), and the control signal X is used so that both are the same. If the amplitude is adjusted (step 306), the pre-chirp amount can be corrected.

このように、簡単な構成で、変調度または駆動クロックの位相ズレを自律補正して、安定なプリチャープ量を補正可能である。   Thus, with a simple configuration, it is possible to correct a stable pre-chirp amount by autonomously correcting the degree of modulation or the phase shift of the drive clock.

尚、本発明は、上述の実施の形態に限定されるものではなく、本発明の要旨を逸脱しない範囲で種々変更、変形して実施することが出来る。   In addition, this invention is not limited to the above-mentioned embodiment, In the range which does not deviate from the summary of this invention, various changes and deformation | transformation can be implemented.

たとえば、フィルタ数、ＰＤ数を増やせば、細かく調整でき、調整精度を上げられる。   For example, if the number of filters and the number of PDs are increased, fine adjustments can be made and adjustment accuracy can be increased.

また、光送信機の駆動クロックの振幅、位相、位相変調器の変調特性が安定している場合、ＦＩＬ-Ｂ、ＦＩＬ-Ｃや、ＰＤ−Ｂ、ＰＤ−Ｃを省略でき、ＰＤ−Ａの受光レベルのみで、プリチャープ量を補正可能である。   Further, when the amplitude and phase of the drive clock of the optical transmitter and the modulation characteristics of the phase modulator are stable, FIL-B, FIL-C, PD-B, and PD-C can be omitted. The pre-chirp amount can be corrected only by the light reception level.

また、透過帯域幅の異なるフィルタ（ＦＩＬ-Ｂ’、ＦＩＬ-Ｃ’）を用いた場合でも、フォトダイオード（ＰＤ−Ｂ’、ＰＤ−Ｃ’）の出力差を透過帯域幅の差を考慮に入れて調整するようにすればよい。   Further, even when filters (FIL-B ′, FIL-C ′) having different transmission bandwidths are used, the output difference of the photodiodes (PD-B ′, PD-C ′) is considered in consideration of the transmission bandwidth difference. You can make adjustments.

このように、本発明によれば、簡単な構成で、変調度または駆動クロックの位相ズレを自律補正して、安定なプリチャープ量を補正可能である。   Thus, according to the present invention, it is possible to correct a stable pre-chirp amount by autonomously correcting the modulation degree or the phase shift of the drive clock with a simple configuration.

長距離光伝送システム等の非線形劣化要因条件が大きい光伝送システムに利用可能である。   It can be used for an optical transmission system having a large nonlinear deterioration factor condition such as a long-distance optical transmission system.

１０ 光信号源
１１ 駆動用クロック源
１２ 位相調整部
１３ 振幅調整部
１４ 位相変調器
１５ 光分波器
１６ 光分岐手段
１７ 光検出手段
１８ 制御手段
１９ メモリ部
２０ 制御手段
２１ メモリ部
２２ 光分岐手段
２３ 光検出手段
２４ 制御手段
２５ メモリ部 DESCRIPTION OF SYMBOLS 10 Optical signal source 11 Drive clock source 12 Phase adjustment part 13 Amplitude adjustment part 14 Phase modulator 15 Optical demultiplexer 16 Optical branching means 17 Photodetection means 18 Control means 19 Memory part 20 Control means 21 Memory part 22 Optical branching means 23 Photodetection means 24 Control means 25 Memory section

Claims (10)

任意の変調方式の光信号を発生する光信号源と、
前記光信号の繰り返し周波数と同じ周波数の駆動クロックを発出する駆動用クロック源と、
前記駆動クロックを用いて前記光信号源からの光信号に位相変調を付加する位相変調器と、
前記位相変調器からの出力光を送信用経路とモニタ用経路に分岐する光分波器と、
前記光分波器からのモニタ用光を1つ以上の波長帯域にフィルタリングする光分岐手段と、
前記光分岐手段にてフィルタリングされた波長帯域の透過光を受光する光検出手段と、
前記駆動クロックの位相を調整する位相調整部と、
前記駆動クロックの振幅を調整する振幅調整部と、
最適なプリチャープを付加するよう前記位相調整部と前記振幅調整部を調整制御する制御手段と、
を備えた光送信装置。 An optical signal source for generating an optical signal of an arbitrary modulation scheme;
A driving clock source for generating a driving clock having the same frequency as the repetition frequency of the optical signal;
A phase modulator for adding phase modulation to the optical signal from the optical signal source using the driving clock;
An optical demultiplexer for branching the output light from the phase modulator into a transmission path and a monitoring path;
Optical branching means for filtering the monitoring light from the optical demultiplexer into one or more wavelength bands;
A light detecting means for receiving transmitted light in a wavelength band filtered by the light branching means;
A phase adjuster for adjusting the phase of the drive clock;
An amplitude adjuster for adjusting the amplitude of the drive clock;
Control means for adjusting and controlling the phase adjustment unit and the amplitude adjustment unit so as to add an optimal pre-chirp;
An optical transmission device comprising: 前記制御手段は、前記光検出手段から出力される結果を記憶するメモリ部を有することを特徴とする請求項１記載の光送信装置。   The optical transmission apparatus according to claim 1, wherein the control unit includes a memory unit that stores a result output from the light detection unit. 前記光分岐手段は、１つ以上の波長帯域にフィルタリングするフィルタを備えたことを特徴とする請求項１又は２記載の光送信装置。   The optical transmission device according to claim 1 or 2, wherein the optical branching unit includes a filter for filtering into one or more wavelength bands. 前記光分岐手段に備えたフィルタは、可変フィルタであることを特徴とする請求項３記載の光送信装置。   The optical transmission device according to claim 3, wherein the filter provided in the optical branching unit is a variable filter. 前記制御手段は、前記光検出手段のフィルタの受光パワーが相違する条件が位相ズレ要因の場合は、位相調整部に対して駆動クロックの位相を調整するよう制御することを特徴とする請求項１又は２記載の光送信装置。   2. The control unit according to claim 1, wherein when the condition that the light reception power of the filter of the light detection unit is different is a phase shift factor, the control unit controls the phase adjustment unit to adjust the phase of the drive clock. Or the optical transmission apparatus of 2. 前記制御手段は、前記位相調整部に対して、フィルタ出力を前記メモリ部に記憶された初期値と同じになるように駆動クロックの位相を調整するよう制御することを特徴とする請求項１又は２記載の光送信装置。   2. The control unit according to claim 1, wherein the control unit controls the phase adjustment unit to adjust a phase of a driving clock so that a filter output is equal to an initial value stored in the memory unit. 3. The optical transmission device according to 2. 前記制御手段は、前記振幅調整部に対して駆動クロックの振幅を調整するよう制御することを特徴とする請求項１又は２記載の光送信装置。   The optical transmission device according to claim 1, wherein the control unit controls the amplitude adjustment unit to adjust an amplitude of a drive clock. 最適なプリチャープを付加するよう位相調整部と振幅調整部を調整制御する制御手段を備えた光送信装置の光送信方法であって、
前記制御手段は、前記振幅調整部に対して駆動クロックの振幅を調整するよう制御することを特徴とする光送信方法。 An optical transmission method of an optical transmission device comprising a control means for adjusting and controlling a phase adjustment unit and an amplitude adjustment unit so as to add an optimal pre-chirp,
The optical transmission method according to claim 1, wherein the control unit controls the amplitude adjusting unit to adjust an amplitude of a drive clock. 最適なプリチャープを付加するよう位相調整部と振幅調整部を調整制御する制御手段を備えた光送信装置の光送信方法であって、
光検出手段のフィルタの受光パワーの相違する条件が位相ズレ要因の場合は、前記位相調整部に対して駆動クロックの位相を調整するよう制御し、次に、メモリ部に格納してある運用設置時のプリチャープ量を示す受光レベルと、調整時の受光レベルとを比較し、両者が同じになるように前記振幅調整部を調整することを特徴とする光送信方法。 An optical transmission method of an optical transmission device comprising a control means for adjusting and controlling a phase adjustment unit and an amplitude adjustment unit so as to add an optimal pre-chirp,
If the condition of the received light power of the filter of the light detection means is a phase shift factor, the phase adjustment unit is controlled to adjust the phase of the drive clock, and then the operation setting stored in the memory unit A light transmission method characterized in that a light reception level indicating a pre-chirp amount at the time is compared with a light reception level at the time of adjustment, and the amplitude adjustment unit is adjusted so that both are the same. 最適なプリチャープを付加するよう位相調整部と前記振幅調整部を調整制御する制御手段を備えた光送信装置の光送信方法であって、
前記制御手段は、前記位相調整部に対して、光検出手段のフィルタ出力をメモリ部に記憶された初期値と同じになるように駆動クロックの位相を調整するよう制御することを特徴とする光送信方法。 An optical transmission method of an optical transmission device comprising a control means for adjusting and controlling a phase adjustment unit and the amplitude adjustment unit so as to add an optimal pre-chirp,
The control unit controls the phase adjustment unit to adjust the phase of the drive clock so that the filter output of the light detection unit becomes the same as the initial value stored in the memory unit. Transmission method.
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