JPH0638595B2 - Light source for WDM optical communication - Google Patents
Light source for WDM optical communicationInfo
- Publication number
- JPH0638595B2 JPH0638595B2 JP60283481A JP28348185A JPH0638595B2 JP H0638595 B2 JPH0638595 B2 JP H0638595B2 JP 60283481 A JP60283481 A JP 60283481A JP 28348185 A JP28348185 A JP 28348185A JP H0638595 B2 JPH0638595 B2 JP H0638595B2
- Authority
- JP
- Japan
- Prior art keywords
- wavelength
- light
- light source
- optical
- optical communication
- 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.)
- Expired - Lifetime
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/50—Transmitters
- H04B10/572—Wavelength control
-
- 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
- H04B10/50—Transmitters
- H04B10/501—Structural aspects
- H04B10/506—Multiwavelength transmitters
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Semiconductor Lasers (AREA)
- Optical Communication System (AREA)
Description
【発明の詳細な説明】 産業上の利用分野 この発明は光通信に用いる波長多重光通信用光源に関す
る。TECHNICAL FIELD The present invention relates to a light source for wavelength division multiplexing optical communication used for optical communication.
従来の技術 波長多重光通信においては、多重度の数だけの波長の異
なる光源が必要になる。波長多重光通信用光源としては
0.8−1.3μmの発振波長を有する発光ダイオード
や半導体レーザ(以下LD)の中から、各チャンネル間
隔に相当する波長のものを選別して用いていた。2. Description of the Related Art In wavelength division multiplexed optical communication, light sources having different wavelengths are required as many as the number of multiplicities. As a light source for wavelength-multiplexed optical communication, a light source having a wavelength corresponding to each channel interval is selected and used from a light emitting diode and a semiconductor laser (hereinafter, LD) having an oscillation wavelength of 0.8 to 1.3 μm.
これまでに実用化している波長多重光通信システムにお
いては、多重度は2から4波長程度のものであり、光源
の波長間隔も0.1−0.2μm間隔に設定し、光源と
なる発光ダイオードやLDの組成材料比を変化させた
り、材料自体をかえることによって希望の波長をえてい
る。In the wavelength-multiplexed optical communication system that has been put to practical use so far, the multiplicity is about 2 to 4 wavelengths, and the wavelength intervals of the light sources are set to 0.1-0.2 μm intervals, and the light-emitting diode serving as the light source is used. The desired wavelength is obtained by changing the composition material ratio of LD or LD, or by changing the material itself.
発光ダイオードを光源とした場合、発光ダイオードのス
ペクトル幅が約30nmと広いために隣接チャンネル間の
クロストークを考慮した場合、発光波長間隔をせまくす
ることが困難である。また、光源に単一モード波長のL
Dを用いた場合、そのスペクトル幅は数10MHz以下であ
るためにチャンネル間がせばめられ、多重度も飛躍的に
高めることが可能となる。When the light emitting diode is used as the light source, it is difficult to narrow the emission wavelength interval when the crosstalk between adjacent channels is taken into consideration because the light emitting diode has a wide spectral width of about 30 nm. In addition, L of the single mode wavelength
When D is used, the spectral width is several tens of MHz or less, so that the channels are interleaved, and the multiplicity can be dramatically increased.
他方、わずかに異なる周期構造を有する分散フィードバ
ックレーザ(Distributed Feedback レーザ(以下DF
Bレーザ))を1つのチップに集積し、アレイ化したも
のがある。On the other hand, a distributed feedback laser (hereinafter referred to as DF) having a slightly different periodic structure.
B laser)) is integrated on one chip to form an array.
第3図にその実施例をしめす。周期の差によって波長の
異なる5つの光をえることが出来る。An example is shown in FIG. Five lights having different wavelengths can be obtained by the difference in the period.
発明が解決しようとする問題点 しかし現在最も多く使用されているファブリーペロー型
の構造を有するLDでは同一プロセスで作成しても、そ
の発振波長はバラツキを生じる。Problems to be Solved by the Invention However, in the LD having the Fabry-Perot type structure which is most frequently used at present, even if the LDs are manufactured by the same process, the oscillation wavelength thereof varies.
このため、多重度の高い波長多重光通信システムを構成
するためには多くのLDのサンプルの中から必要とする
波長のものを選別するか、設計値に近い波長を有するL
Dを温度制御して設計値の波長にしている。このためL
Dの歩留りが悪くなってしまう。また波長間隔を広くす
るとLDの歩留りは良くなるが、各チャンネルにおいて
光ファイバーの伝送損失が異なるためにシステムとして
のパワーマージンが最悪のチャンネルによって決定され
てしまう。他の光学部品においても特性の変化が生ず
る。このため部品によってはチャンネルで材料や構成を
変える必要が生じ、コストアップとなってしまう。Therefore, in order to construct a wavelength division multiplexing optical communication system with a high degree of multiplexing, a sample having a required wavelength is selected from many LD samples, or an L having a wavelength close to a design value is selected.
The temperature of D is controlled to the designed wavelength. Therefore, L
The yield of D becomes worse. Further, if the wavelength interval is widened, the yield of the LD is improved, but since the transmission loss of the optical fiber is different in each channel, the power margin of the system is determined by the worst channel. The characteristics of other optical components also change. For this reason, it is necessary to change the material and structure of the channel depending on the component, which increases the cost.
第3図に示したDFBレーザアレイではその作成プロセ
スが複雑であり、導波路部に構成する溝のピッチをきわ
めて精密に制御しなければならず、素子の再現性や歩留
りに大きな問題がある。また素子がアレイ状になってい
るためにLDを同時駆動した場合、発熱しLDの温度上
昇をまねく。従って波長変化や出力レベルの低下を召
く。The DFB laser array shown in FIG. 3 has a complicated manufacturing process, and the pitch of the grooves formed in the waveguide portion must be controlled extremely precisely, which causes a serious problem in reproducibility and yield of the device. Further, since the elements are arrayed, when the LDs are driven simultaneously, heat is generated and the temperature of the LDs rises. Therefore, the wavelength change and the output level decrease are desired.
本発明は上記問題に鑑み、LDの発振周波数を安定化
し、多重度の高い波長多重光通信用光源を提供するもの
である。In view of the above problems, the present invention provides a light source for wavelength division multiplexed optical communication that stabilizes the oscillation frequency of an LD and has a high degree of multiplexing.
問題点を解決するための手段 上記問題点を解決するために本発明の波長多重光通信用
光源は複数個のLDも外部に複数本の光ファイバーと1
枚の平面回折格子と1つのレンズと複数枚の反射鏡を具
備し、光ファイバー出射端と複数枚の反射鏡、平面回折
格子及びレンズをリトロー型に配置し、各LDに対して
特定波長の外部光共振器を形成したものである。Means for Solving the Problems In order to solve the above problems, the light source for wavelength division multiplexing optical communication of the present invention has a plurality of LDs and a plurality of optical fibers on the outside.
It is equipped with one plane diffraction grating, one lens and a plurality of reflection mirrors, and the optical fiber output end and a plurality of reflection mirrors, a plane diffraction grating and a lens are arranged in a Littrow type, and each LD has a specific wavelength outside. An optical resonator is formed.
作用 本発明は上記した構成によって、光学系を簡素化し複数
個のLDの発振周波数を同時に独立に安定化制御するこ
とによって上記に説明した問題点を解決しようとするも
のである。Action The present invention is intended to solve the above-mentioned problems by simplifying the optical system and stabilizing the oscillation frequencies of a plurality of LDs independently and simultaneously by the above-mentioned configuration.
実施例 以下、本発明の1実施例における波長多重光通信用光源
について図面を参照しながら説明する。第1図は本発明
の1実施例における波長多重光通信用光源の構成図を示
すものである。複数個のLD1からの出力光は各々光フ
ァイバー2に入力される。光ファイバーの各出射端はコ
リメートレンズ3の焦点面(x−y平面)上に配置す
る。4は平面回折格子で溝はY方向に切られている。こ
のため光ファイバー2の配列はLD間のクロストークを
さけるために、y方向では重ならないようにしなければ
ならない。第1図における実施例では、光ファイバー2
はすべてy軸方向に配列してあるが必ずしも同一x座標
上に配列する必要はなく、斜め方向に配列してもよい。
光ファイバー2よりでた光は、コリメートレンズ3によ
り平行光となって平面回折格子4に入射される。いま、
平面回折格子4の溝に対に対して垂直な平面(X−N
面)での光の入射角、回折角をα、βとし、またオフプ
レイン角をφとすると波長λの光は、 d・cosφ・(sinα+sinβ)=mλ ……(1) を満たす。但し、dは溝間隔、mは次数である。もし、
入射角とオフプレイン角が一定ならば、入射光の波長λ
が変化すると回折角βが変化する。Embodiment Hereinafter, a light source for wavelength division multiplexing optical communication in one embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a block diagram of a light source for wavelength division multiplexing optical communication in one embodiment of the present invention. Output light from the plurality of LDs 1 is input to the optical fiber 2. Each exit end of the optical fiber is arranged on the focal plane (xy plane) of the collimator lens 3. Reference numeral 4 is a plane diffraction grating having grooves cut in the Y direction. For this reason, the arrangement of the optical fibers 2 must be such that they do not overlap in the y direction in order to avoid crosstalk between the LDs. In the embodiment shown in FIG. 1, the optical fiber 2
Are all arranged in the y-axis direction, but it is not always necessary to arrange them on the same x coordinate, and they may be arranged obliquely.
The light emitted from the optical fiber 2 is collimated by the collimator lens 3 and is incident on the plane diffraction grating 4. Now
A plane perpendicular to the pair of grooves of the plane diffraction grating 4 (X-N
When the incident angle and the diffraction angle of light on the surface are α and β, and the off-plane angle is φ, the light of wavelength λ satisfies d · cosφ · (sinα + sinβ) = mλ (1). However, d is a groove interval and m is an order. if,
If the incident angle and the off-plane angle are constant, the wavelength λ of the incident light
The diffraction angle β changes as is changed.
Δβ変化すると集光レンズ3の焦点面ではΔx=Δβ・
fに対応する。When Δβ changes, Δx = Δβ · on the focal plane of the condenser lens 3.
Corresponds to f.
fは集光レンズ3の焦点距離である。LD1の出力光は
光ファイバー2を通りレンズ3で平行光となって平面回
折格子4で回折される。回折された光は、集光レンズ3
の焦点面上で波長に対応した位置に集光される。FP型
LDにおいては、発振可能な縦モードが複数本存在する
ので、特定波長に対応する、レンズ3の焦点面上の位置
に反射鏡6を配置すると、LD1においてその特定波長
に対してだけ外部光共振器が形成される。従ってLD1
の発振波長は(1)式によって幾何学的に決定される。ま
た、レンズ3の焦点面の反射鏡6の(x−y)面内の位
置を変えることによって、共振周波数が変化し、LD1
の発振周波数も利得の範囲内で変化させることができ
る。従って、波長多重光通信用光源としてある一定の波
長間隔で発振するLD光源が必要な場合、第1図に示さ
れるように反射鏡6を複数個を必要な波長位置に配列
し、しかも光ファイバーの出射端をy軸方向に分散して
配置することにより各LD1の回折光を集光レンズ5の
焦点面上においてy軸方向に分散して結像させ、各LD
1の利得の広がりによって生ずるスペクトルの裾の重り
をレンズ5の焦点面上で回避しながら、前記反射鏡6を
x−y面において2次元的に配列し、外部光共振器を形
成してやればよい。第2図にレンズ3の焦点面での各L
D1の結像スペクトルを示す。各LDが縦マルチモード
で発振していると1つのLD1の発振スペクトルはx方
向に分散して結像される。特定の縦モードスペクトルの
結像点に反射鏡6を配置すると、反射鏡6上に結像され
た発振スペクトル像7を光源として再び元の光路を通り
LDへ帰還される。第2図のa,b,c,d,eのスペ
クトルは、第1図のLD1a,b,c,d,eの発光ス
ペクトルに対応している。f is the focal length of the condenser lens 3. The output light of the LD 1 passes through the optical fiber 2, becomes parallel light by the lens 3, and is diffracted by the plane diffraction grating 4. The diffracted light is collected by the condenser lens 3
The light is focused at a position corresponding to the wavelength on the focal plane of. Since there are a plurality of longitudinal modes capable of oscillating in the FP type LD, when the reflecting mirror 6 is arranged at a position on the focal plane of the lens 3 corresponding to a specific wavelength, the LD 1 causes an external light only for the specific wavelength. An optical resonator is formed. Therefore LD1
The oscillation wavelength of is geometrically determined by Eq. (1). In addition, by changing the position of the focal plane of the lens 3 in the (xy) plane of the reflecting mirror 6, the resonance frequency changes, and the LD1
The oscillation frequency of can also be changed within the range of gain. Therefore, when an LD light source that oscillates at a certain wavelength interval is required as a wavelength multiplexing optical communication light source, a plurality of reflecting mirrors 6 are arranged at required wavelength positions as shown in FIG. By arranging the emitting ends in a distributed manner in the y-axis direction, the diffracted light of each LD 1 is dispersed in the y-axis direction on the focal plane of the condenser lens 5 to form an image.
An external optical resonator may be formed by arranging the reflecting mirrors 6 two-dimensionally in the xy plane while avoiding the weight of the bottom of the spectrum caused by the spread of the gain of 1 on the focal plane of the lens 5. . Each L in the focal plane of the lens 3 is shown in FIG.
The imaging spectrum of D1 is shown. When each LD oscillates in the longitudinal multimode, the oscillation spectrum of one LD1 is dispersed and imaged in the x direction. When the reflecting mirror 6 is arranged at the image forming point of the specific longitudinal mode spectrum, the oscillation spectrum image 7 formed on the reflecting mirror 6 is used as a light source and is returned to the LD again through the original optical path. The spectra of a, b, c, d, and e of FIG. 2 correspond to the emission spectra of LD 1a, b, c, d, and e of FIG.
なお、本実施例では、平面回折格子4での1次の回折光
の帰還にはレンズ5と反射鏡6によって構成されたキャ
ッツアイ光学系を用いているために安定した光帰還が行
なえる。In the present embodiment, since the cat's eye optical system including the lens 5 and the reflecting mirror 6 is used for returning the first-order diffracted light at the plane diffraction grating 4, stable optical feedback can be performed.
また、LD1の出力光はファイバー2によって外部光共
振器に導かれているために、LDアレイとは異なり、各
LD1を独立に温度制御することが可能となる。Further, since the output light of the LD1 is guided to the external optical resonator by the fiber 2, it becomes possible to independently control the temperature of each LD1 unlike the LD array.
発明の効果 以上のように本発明は複数個のLDの外部に、1つのレ
ンズと一枚の平面回折格子と、前記LDからの出力光を
導く光ファイバーと、複数個の反射鏡を具備し、光学系
が簡素なリトロー配置を用いてLD外部に周波数選択性
のある光共振器を構成し、複数個のLDを独立にかつ選
択的に単一モード発振させることによって、周波数を安
定化し、周波数間隔が狭く多重度の高い波長多重光通信
用の光源を提供することができうる。As described above, the present invention includes, outside the plurality of LDs, one lens, one plane diffraction grating, an optical fiber for guiding the output light from the LDs, and a plurality of reflecting mirrors. An optical resonator having frequency selectivity is configured outside the LD using a Littrow arrangement with a simple optical system, and a plurality of LDs are independently and selectively oscillated in a single mode to stabilize the frequency, It is possible to provide a light source for wavelength division multiplexing optical communication with a narrow interval and a high degree of multiplexing.
第1図は本発明の実施例における波長多重光通信用光源
の構成図、第2図はレンズの焦点面上のLDの発光スペ
クトル図、第3図は従来の実施例を示す斜視図である。 1……半導体レーザー、2……光ファイバー、3……コ
リメートレンズ、4……平面回折格子、6……反射鏡FIG. 1 is a configuration diagram of a light source for wavelength division multiplexing optical communication in an embodiment of the present invention, FIG. 2 is an emission spectrum diagram of an LD on a focal plane of a lens, and FIG. 3 is a perspective view showing a conventional embodiment. . 1 ... Semiconductor laser, 2 ... Optical fiber, 3 ... Collimating lens, 4 ... Planar diffraction grating, 6 ... Reflecting mirror
Claims (2)
ーザ素子の出力光を導波する複数本の光ファイバーと前
記複数本の光ファイバーからの出力光を平行光にする1
つのコリメータレンズと前記コリメータレンズによっ
て、コリメートされた前記複数本の光ファイバからの出
力光を、発振波長に応じた方向へ分散させる平面回折格
子と、前記平面回折格子で分散された光を選択的に前記
光ファイバーの出射部へ帰還させる反射鏡を備え、前記
反射鏡と上記光ファイバーの出射端を一個のコリメート
レンズの同一焦点面上に配置したリトロー型光学系を用
いたことを特徴とする波長多重光通信用光源。1. A plurality of semiconductor laser elements, a plurality of optical fibers for guiding output light of the semiconductor laser elements, and output light from the plurality of optical fibers are collimated.
A collimator lens and a plane diffraction grating that disperses the output light from the plurality of optical fibers collimated by the collimator lens in a direction according to the oscillation wavelength, and the light dispersed by the plane diffraction grating is selectively In addition, a Littrow type optical system is used, in which a reflecting mirror for returning to the emitting part of the optical fiber is provided, and the reflecting mirror and the emitting end of the optical fiber are arranged on the same focal plane of one collimating lens Light source for optical communication.
の溝に対する法線に対して斜めに入射するように光ファ
イバーをコリメートレンズの焦点面に配列した特許請求
の範囲第(1)項記載の波長多重光通信用光源。2. The wavelength according to claim 1, wherein the optical fibers are arranged on the focal plane of the collimating lens so that the light emitted from the optical fibers enters obliquely with respect to the normal to the groove of the plane diffraction grating. Light source for multiplex optical communication.
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP60283481A JPH0638595B2 (en) | 1985-12-17 | 1985-12-17 | Light source for WDM optical communication |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP60283481A JPH0638595B2 (en) | 1985-12-17 | 1985-12-17 | Light source for WDM optical communication |
Publications (2)
Publication Number | Publication Date |
---|---|
JPS62142426A JPS62142426A (en) | 1987-06-25 |
JPH0638595B2 true JPH0638595B2 (en) | 1994-05-18 |
Family
ID=17666102
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
JP60283481A Expired - Lifetime JPH0638595B2 (en) | 1985-12-17 | 1985-12-17 | Light source for WDM optical communication |
Country Status (1)
Country | Link |
---|---|
JP (1) | JPH0638595B2 (en) |
Families Citing this family (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP2676875B2 (en) * | 1989-02-09 | 1997-11-17 | 松下電器産業株式会社 | External cavity type semiconductor laser and wavelength division multiplexing optical transmission device |
US5526155A (en) * | 1993-11-12 | 1996-06-11 | At&T Corp. | High-density optical wavelength division multiplexing |
FR2779535B1 (en) * | 1998-06-04 | 2000-09-01 | Instruments Sa | COMPACT MULTIPLEXER |
DE102004053137A1 (en) * | 2004-10-29 | 2006-05-11 | Raab, Volker, Dr. | Multispectral laser with multiple gain elements |
-
1985
- 1985-12-17 JP JP60283481A patent/JPH0638595B2/en not_active Expired - Lifetime
Also Published As
Publication number | Publication date |
---|---|
JPS62142426A (en) | 1987-06-25 |
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