JPS60121424A - Optical receiver - Google Patents
Optical receiverInfo
- Publication number
- JPS60121424A JPS60121424A JP58229649A JP22964983A JPS60121424A JP S60121424 A JPS60121424 A JP S60121424A JP 58229649 A JP58229649 A JP 58229649A JP 22964983 A JP22964983 A JP 22964983A JP S60121424 A JPS60121424 A JP S60121424A
- Authority
- JP
- Japan
- Prior art keywords
- light
- signal
- optical
- polarization state
- polarization
- 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 38
- 230000010287 polarization Effects 0.000 claims abstract description 67
- 238000012545 processing Methods 0.000 claims abstract description 8
- 230000005540 biological transmission Effects 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 8
- 229940125730 polarisation modulator Drugs 0.000 claims description 7
- 238000001514 detection method Methods 0.000 abstract description 16
- 239000013307 optical fiber Substances 0.000 abstract description 8
- 230000010355 oscillation Effects 0.000 abstract 5
- 239000013078 crystal Substances 0.000 description 5
- 230000006866 deterioration Effects 0.000 description 5
- 238000003780 insertion Methods 0.000 description 5
- 230000037431 insertion Effects 0.000 description 5
- 239000000126 substance Substances 0.000 description 5
- 230000007423 decrease Effects 0.000 description 4
- 239000000463 material Substances 0.000 description 4
- 238000010586 diagram Methods 0.000 description 3
- 238000005516 engineering process Methods 0.000 description 2
- 229910003327 LiNbO3 Inorganic materials 0.000 description 1
- 238000006243 chemical reaction Methods 0.000 description 1
- 238000004891 communication Methods 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000012937 correction Methods 0.000 description 1
- 230000002542 deteriorative effect Effects 0.000 description 1
- 230000005684 electric field Effects 0.000 description 1
- 230000001747 exhibiting effect Effects 0.000 description 1
- 239000000284 extract Substances 0.000 description 1
- 239000000835 fiber Substances 0.000 description 1
- 230000004044 response Effects 0.000 description 1
- 239000004065 semiconductor Substances 0.000 description 1
- 239000004575 stone Substances 0.000 description 1
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
- G02F2/00—Demodulating light; Transferring the modulation of modulated light; Frequency-changing of light
- G02F2/002—Demodulating light; Transferring the modulation of modulated light; Frequency-changing of light using optical mixing
-
- 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
- H04B10/60—Receivers
- H04B10/61—Coherent receivers
- H04B10/615—Arrangements affecting the optical part of the receiver
- H04B10/6151—Arrangements affecting the optical part of the receiver comprising a polarization controller at the receiver's input stage
-
- 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
- H04B10/60—Receivers
- H04B10/61—Coherent receivers
- H04B10/64—Heterodyne, i.e. coherent receivers where, after the opto-electronic conversion, an electrical signal at an intermediate frequency [IF] is obtained
Landscapes
- Physics & Mathematics (AREA)
- Electromagnetism (AREA)
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- General Physics & Mathematics (AREA)
- Nonlinear Science (AREA)
- Optics & Photonics (AREA)
- Optical Communication System (AREA)
Abstract
Description
【発明の詳細な説明】
本発明は、光通信において、光ヘテロダイン方式に適用
できる受信装置に関するものである。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a receiving device applicable to an optical heterodyne system in optical communication.
元ヘテロダイン検波形の光受信装置、つまシ。An optical receiver with original heterodyne detection waveform, Tsumashi.
光伝送路から入力された信号光を局発光源からの局発光
と合成した後に光検波して信号を潜る光受信装置は１局
発光電力を十分に確保することにょシ良好な８Ｎ比を達
成できるという特徴を有している。光検波６に入力する
信号光電力をＰａ１局発光電力をＰｆｆｌ 、検波器の
光這父換係数をＤとすると、検波後の電気信号電力Ｐは
Ｐ ＝ ２ ＫＤ２Ｐ８Ｐ、 −−−−−−−−−−ｆ
ｉｌで与えられる。ここで、には信号光と局発光の偏光
状態の整合度を表わす係数であシ（Ｏ≦に≦１）。The optical receiving device, which combines the signal light input from the optical transmission line with the local light from the local light source and then optically detects the signal, achieves a good 8N ratio by ensuring sufficient light power for each station. It has the characteristic of being able to Assuming that the signal optical power input to the optical detection 6 is Pa1, the station light emission power is Pffl, and the optical phase conversion coefficient of the detector is D, the electrical signal power P after detection is P = 2 KD2P8P, ---------- ---f
It is given by il. Here, is a coefficient representing the matching degree of the polarization states of the signal light and the local light (O≦≦1).
両者の偏光状態が一致したときに＝１となる。一方、検
波後の雑音電力Ｎは、局発光電力Ｐ、が十分に大きい場
会１局発光に起因するショッ）雑音が他の原因による雑
音をおおいかくしてしまい。=1 when both polarization states match. On the other hand, if the noise power N after detection is sufficiently large, the noise caused by one station's light emission will overshadow the noise caused by other causes.
１’Ｊ＝＝４６ＤＰ沼Ｂ −−−−−−−−一−＋２１
となる。ここで、ｇは重子電荷、Ｂは信号帯域幅である
。したがって、局発光が十分に大きいショット雑音限界
の検波では、検波後のＳＮ比は。1'J==46DP Swamp B −−−−−−−−1−+21
becomes. Here, g is the deuteron charge and B is the signal bandwidth. Therefore, in shot noise limit detection where the local light is sufficiently large, the SN ratio after detection is:
となる。becomes.
光伝送路を通過した光信号は一般に任意の方向に主軸を
有する（６円偏光となっており、さらに伝送路の温度変
動や外力の変動によってその偏光状態が変化する。した
がって、直接局発光と合波して検波すると、上式のＫが
低下、変動し、検波信号車力およびＳＮ比の低下、変動
をもたらすので。An optical signal that has passed through an optical transmission line generally has its principal axis in an arbitrary direction (it is 6-circularly polarized light, and its polarization state changes depending on temperature fluctuations in the transmission line or fluctuations in external force. Therefore, it is not directly local light). When multiplexed and detected, K in the above equation decreases and fluctuates, resulting in a decrease and fluctuation in the detection signal strength and S/N ratio.
良好なＳＮ比を確保するためには、信号光の偏光状態と
局発光の偏光状態とが常に一致しているように制御する
必要がある。In order to ensure a good S/N ratio, it is necessary to control the polarization state of the signal light and the polarization state of the local light so that they always match.
第１図に偏光状態の制御系を装備した従来形の光受信装
置を示す。同図において１は光伝送路として用いる光フ
ァイバ、２は信号光の偏光状態を制御する偏光補償回路
、３は信号光の偏光状態を検知するために信号光の一部
をとり出す分波器、４は信号光の偏光状態を検出して偏
光補償回路２を制御するための（Ｎ号を作り出す偏光検
出回路。FIG. 1 shows a conventional optical receiver equipped with a polarization state control system. In the figure, 1 is an optical fiber used as an optical transmission path, 2 is a polarization compensation circuit that controls the polarization state of signal light, and 3 is a demultiplexer that extracts a part of the signal light to detect the polarization state of signal light. , 4 is a polarization detection circuit that detects the polarization state of the signal light and generates (N) for controlling the polarization compensation circuit 2.
５は局発光源、６は光ファイバ１から入力された信号光
と局発光源５からの局発光とを合成する合波器、７は光
検波器、８は信号処理回路、９は信号出力端子である。5 is a local light source, 6 is a multiplexer that combines the signal light input from the optical fiber 1 and the local light from the local light source 5, 7 is a photodetector, 8 is a signal processing circuit, and 9 is a signal output It is a terminal.
従来形の装置では、信号光の一部をとシ出してその偏光
状態を検出し、帰還制菌することによυ信号光の１（４
光状態を局発光の偏光状態（一般に直、６３１ ｆｕ元
）に一致させている。ここで、偏光補償回路２における
偏光状態制御の方１去としては、任意のｍ円偏光は複屈
折性を示す２つの物質を用いて所望の直線偏光に変換で
きるということを利用している。第２図に、その制御方
法の一例を示す。いま、第２図（ａ）に示すような楕円
偏光をＸ軸方向の直線偏光に変換しようとする場合、ま
ず、第１の物質の複屈折性を制御して楕円偏光の主軸Ａ
を回転させ、主軸ＡをＸ軸と一致させる（第２図（ｂ）
）。次いで、χ軸又はＸ軸方向に結晶軸を有する第２の
複屈折か物質を制御してχ軸方向、ｙｌ＋方向の鴫波成
分の位相差を補償し、直線偏光を作シ出す（嬉２図（Ｃ
））。ここで、χ−ｙ軸系はＸ−Ｙ軸系と４５９の角度
をなしている。In conventional devices, part of the signal light is emitted, its polarization state is detected, and 1 (4) of the signal light is
The optical state is made to match the polarization state of local light (generally direct, 631 fu elements). Here, the polarization state control in the polarization compensation circuit 2 utilizes the fact that arbitrary m-circularly polarized light can be converted into desired linearly polarized light using two substances exhibiting birefringence. FIG. 2 shows an example of the control method. Now, when trying to convert elliptically polarized light as shown in Fig. 2(a) into linearly polarized light in the X-axis direction, first, the birefringence of the first substance is controlled to change the principal axis A
rotate to align the main axis A with the X axis (Fig. 2 (b)
). Next, a second birefringent substance having a crystal axis in the χ axis or the Figure (C
)). Here, the χ-y axis system makes an angle of 459 with the X-Y axis system.
楕円偏光の主軸を（ｎ転させる第１の物質としては。As the first substance that rotates the principal axis of elliptically polarized light (n).
だとえは半波長板が用いられ、その結晶軸の方向を制御
する。寸だ、偏波面回転素子を用いることもできる。一
方、第２段階の位相差を補償する方法としては、たとえ
ばバビネーソレイコの補償板の結晶長゛と変化させる方
法、ＬｉＮｂＯ３などの電気−光学変調器を用いる方法
など≠；ある。また。A half-wave plate is used to control the direction of the crystal axis. Indeed, a polarization plane rotation element can also be used. On the other hand, methods for compensating the phase difference in the second stage include, for example, a method of changing the crystal length of a Babinet-Soleiko compensator, a method of using an electro-optic modulator such as LiNbO3, etc. Also.
互いに結晶４ｉ１＋が４５度傾動た２つの電気−光学変
調器を用いても、楕円偏光を［線偏光に変換することが
できる。It is also possible to convert elliptically polarized light into linearly polarized light using two electro-optic modulators whose crystals 4i1+ are tilted by 45 degrees with respect to each other.
しかし、このように信号光の偏光状態を制御して局発光
の偏光状態に一致させる従来技術では、信号光の偏光状
態を検出するために信号光の一部分取り出しているので
、光検波器に到達する信号光電力が減少する。オた。偏
光補償回路の挿入損失も信号光電力の低下をまねく。元
ファイバを通過した信号光電力をＰ、。とすると、検波
器に入力する信号光の電力Ｐ は
Ｐ６−α。αｄα、。８ Ｐｓｏ −−−−−−−−−
−−（４１となる。ここで、α０ 、αｄ、α□、はそ
れぞれ偏光補償回路１分波器１合波器の挿入損である。However, in the conventional technology that controls the polarization state of the signal light to match the polarization state of the local light, a portion of the signal light is extracted to detect the polarization state of the signal light, so that the polarization state of the signal light does not reach the optical detector. The signal light power to be used decreases. Ota. Insertion loss of the polarization compensation circuit also causes a decrease in signal optical power. The power of the signal light passing through the original fiber is P. Then, the power P of the signal light input to the detector is P6-α. αdα,. 8 Pso -----------
--(41. Here, α0, αd, α□ are the insertion losses of the polarization compensation circuit 1 demultiplexer 1 multiplexer, respectively.
一方、検波器に入力する局発光電力〜は１局発光源の出
力をＰ 、合波器の挿入損をａｍ、とすると。On the other hand, for the local light power input to the detector, suppose that the output of one local light source is P, and the insertion loss of the multiplexer is am.
０
Ｐ、！３＝αｍＪ３ＰＡｏ −−−−−−−−−一−−
−−（５１で与えられる。したがって、検波後の電気信
号電力、雑音ａ力、ＳＮ比は。0P,! 3=αmJ3PAo −−−−−−−−−−
--(51) Therefore, the electrical signal power after detection, the noise a power, and the S/N ratio are:
Ｐ＝２ＫＤ２α。αｄα□、α＋ｎＪＰｓｏＰｓ−＆
−−−−−（６）となる。ここで、偏波制御を行ってい
るため、Ｋ＝ｌである。なシ、閤波ルＵ御を行わない場
合。P=2KD2α. αdα□, α+nJPsoPs-&
-----(6). Here, since polarization control is performed, K=l. If you do not perform the control.
すなわち、偏光補償回路２１分波器３．偏光検出回路４
といった偏光状態を制御するだめの特別な回路を装備し
ない場合には、電気信号電力Ｐ。。That is, the polarization compensation circuit 21, the demultiplexer 3. Polarization detection circuit 4
If a special circuit for controlling the polarization state is not installed, the electrical signal power P. .
雑音電力Ｎ。、ＳＮ比５ＮＲｏは。Noise power N. , the S/N ratio is 5NRo.
Ｐ＝ ２ＫＤ２α α Ｐ Ｐ −一−−−−（９１０
ｍｓ ｍＪＪ ｓｏ ５ｆｆｌ
Ｎ＝４εＤα Ｐ Ｂ −−−−−一−−−−−ＱＯ）
ｏ ｍ沼 石Ｏ
ｓ ＮＲ＝Ｉ ＫＤ 。Ｐ −−−−−＝−−−１ｌｌ
）ｏ ２ ｇＢ ｌＴ１８８０
であり、Ｋは１よシかなシ小さくかつ変動する。P= 2KD2α α P P −1−−−−(910
ms mJJ so 5ffl N=4εDα P B −−−−−−−−−−−QO)
o m swamp stone O s NR=I KD. P -------=----1ll
)o 2 gB lT1880 , and K is small and fluctuates by around 1.
したがって、従来装置では、偏光状態の制御系を装備す
ることによシ、常にＫを十分１に近づけることができ、
偏光状態の不整合に起因するＳＮ比劣１ヒは除去できた
。しかし、偏光状態を制御する機構を新しくとりつけた
ために、α。α、なる大きさの新しいＳＮ比劣化を生じ
るという欠点を有していた。ここで、２つの複屈折性物
質から成る偏光補償回路の挿入損失は３〜１０ｄＢ程度
であシ。Therefore, in the conventional device, by being equipped with a polarization state control system, K can always be kept sufficiently close to 1.
It was possible to eliminate the poor S/N ratio caused by mismatching of polarization states. However, because we installed a new mechanism to control the polarization state, α. This method has the disadvantage of causing a new SN ratio deterioration of a magnitude of α. Here, the insertion loss of the polarization compensation circuit made of two birefringent materials is about 3 to 10 dB.
分波器による損失を１ｄＢ とすると、計４〜１１ｄＢ
程度のＳＮ比劣化となる。If the loss due to the duplexer is 1 dB, the total is 4 to 11 dB.
This results in a slight deterioration of the SN ratio.
本発明は、上記事情を考慮してなされたもので′あシ、
光伝送路から入力された信号光を局発光源の局発光と合
波した後に光検波して信号を得る光ヘテロダイン形の光
受信装置において１局発光の偏光状態を制御して信号光
の偏光状態に一致させることによシ、最大の８Ｎ比を得
ることを目的とする。The present invention has been made in consideration of the above circumstances.
In an optical heterodyne type optical receiver that obtains a signal by optically detecting the signal light input from the optical transmission line and combining it with the local light from the local light source, the polarization state of the single local light is controlled to polarize the signal light. The aim is to obtain the maximum 8N ratio by matching the conditions.
以下１本発明を第３図に示す実施例にょシ説明する。The present invention will be explained below using an embodiment shown in FIG.
同図において、１は光ファイバ、５は局発光源、６は合
波器、７は光検波器、９は信号出力端子、１０は局発光
の偏光状態を変化させて信号光の偏光状態に一致させる
偏光変調器、１１はその出力信号が最大となるように偏
光変調器１ｏを制御する１Ｍ号を発生させる信号処理回
路である。In the figure, 1 is an optical fiber, 5 is a local light source, 6 is a multiplexer, 7 is a photodetector, 9 is a signal output terminal, and 10 is a polarization state of the signal light by changing the polarization state of the local light. The matching polarization modulator 11 is a signal processing circuit that generates a 1M signal that controls the polarization modulator 1o so that its output signal becomes maximum.
本装置は、局発光の偏光状態を制御するものであシ、そ
の構成部品としては従来装置と同様のものを使用できる
。たとえば１局発光源５としては半導体レーザ、合波器
６としてはビームスプリッタまたは光結合器、光検波器
７としてはフォトダイオードを用いる。信号処理回路１
１は、検波後の電気信号電力の最大点を検出する機能と
制御信号を発生する機能を有する電気回路である。なお
。This device controls the polarization state of local light, and the same components as those of conventional devices can be used as its components. For example, a semiconductor laser is used as the single light source 5, a beam splitter or optical coupler is used as the multiplexer 6, and a photodiode is used as the photodetector 7. Signal processing circuit 1
Reference numeral 1 denotes an electric circuit having a function of detecting the maximum point of electric signal power after detection and a function of generating a control signal. In addition.
偏光変調器１０の具体例については後述する。A specific example of the polarization modulator 10 will be described later.
光ファイバーを通過し、光検波器７に到達した信号光の
電界Ｅ は、一般に直交する直線調光を用いて。The electric field E of the signal light that has passed through the optical fiber and reached the photodetector 7 is generally controlled using orthogonal linear dimming.
−−−−−−−−−−−−−（１２１ で表される。ここで、ω８ は信号光の角周波数。--------------(121 It is expressed as Here, ω8 is the angular frequency of the signal light.
”’８Ｘ ＋ φ８ｘはχ方向の偏光成分の振幅と位相
。``'8X + φ8x is the amplitude and phase of the polarization component in the χ direction.
Ｅ８ｙ、φ３ｚ はｙ方向の偏光成分の振幅と位相であ
υ。E8y, φ3z are the amplitude and phase of the polarization component in the y direction υ.
は信号光電力である。同様にして、光検波器７に到達し
た局発光の直昇Ｅ 、電力Ｐ、は。is the signal optical power. Similarly, the direct rise E and power P of the local light that reached the optical detector 7 are as follows.
沼
％＝ ｅｚｐ（３ｏＡｔ＋−（ト、Ｆ：、２ｙｅｅ６φ
７ｚ”Ｊ：１９６．ｙｅｎすφン、））−−−−−−−
−−−−（！４１
−−−−−−−−−−− ｆｌ団
で与えられる。ここで、ω看は局発光の角周波数。Swamp% = ezp(3oAt+-(t, F:, 2yee6φ
7z"J:196.yensuφn,))------
-----(!41 ----------------- It is given by the fl group. Here, ω is the angular frequency of the local light.
〜よ Ｅ、、、φＡｘ 、φＩＩアはそれぞれ直線偏光
成分の振幅１位相である。光検波後の送気信号覆（！Ｏ
Ｒ（（φ１−φｓｙ、 ’ −”−ｅｘ−φ、、））
〕−−−−−−−−−−−［＋６１
となる。上式で
Ｅ８ｙ／Ｅ、よ＝ Ｆ：、 ／−７−−−−−−−−−
−（１７）φ、７−φ、ｙ−りえ一φｐｙ−−−−−−
−−−−を国のとき、すなわち、信号光の偏光状態と局
発光の偏光状態が一致したとき電気信号電力は最大とな
り。〜Yo E, , φAx, φIIa are each the amplitude and 1 phase of the linearly polarized light component. Air supply signal after optical detection (!O
R((φ1−φsy, ' −”−ex−φ,, ))
]------------[+61] In the above formula, E8y/E, yo=F:, /-7−−−−−−−−
-(17)φ, 7-φ, y-Rieichiφpy------
----- When the signal light and the polarization state of the local light match, that is, the electric signal power becomes maximum.
Ｐ ＝ ２Ｄ２Ｐ Ｐ沼 −−一一一一−−−−−−θ
０ｍａｘ ａ
となる。ここで１式（１）のに、すなわち、信号光と局
発光の偏光状態の整合度を表す係数はに＝Ｐ ／Ｐｍａ
ｘ−−−−−−−−−−−ｇ）で与えられる。P = 2D2P P swamp ---1111-----θ
0max a. Here, in equation (1), the coefficient representing the degree of matching of the polarization states of the signal light and the local light is = P /Pma
x------------g).
信号光がある偏光状態をもつとき、Ｐ すなａＸ
わちに＝１を達成するためには、−ｘ／Ｅ訂（又はＥｉ
、／Ｅ、）およびφ、ア、−φ、ｙの２つを制御する必
要がある。ＰはＥ ／Ｅ 、φ −φ の沼χ Ｊ １
χ Ｊ３ｙ
２変数に対し′て単調に変化するので、Ｐが大きくなる
ように順次”Ｊ３Ｘ／１ｉｌｉ、’φ５、−リア、を変
化させれば必ず最大値Ｐ 全達成することができる。When the signal light has a certain polarization state, in order to achieve P = aX, that is, = 1, -x/E correction (or Ei
, /E,) and φ,a, -φ,y. P is E /E, φ − φ swamp χ J 1
Since χ J3y changes monotonically with respect to the two variables, the maximum value P can always be achieved by changing "J3X/1ili, 'φ5, - rear" sequentially so that P becomes larger.
ａＸ
また、信号光の偏光状態が変ｉＪＪ＋ １．ても、常に
その変動に追随して局発光の偏光状態を変化させ、信号
光の偏光状態と一致させることができる。aX Also, the polarization state of the signal light changes iJJ+ 1. However, the polarization state of the local light can always be changed to match the polarization state of the signal light by following the fluctuations.
具体的には、従来方式と同じように２つの複屈折性物質
を用いて局発光の偏光状態を制御する。Specifically, as in the conventional method, two birefringent substances are used to control the polarization state of the local light.
局発光源の出力は一般に直？８偏光であシ、たとえば、
その偏光方向と４５度の角度をなす結晶軸を有する複屈
折性物質を用いて位相差を制御して信号光と同一の楕円
ｍ）ｉ：（ただし、主軸の方向は異なる）を作シ、続い
て第２の複屈折性物質を制御し゛ＣＣ線軸回転させれば
１局発光の偏光状態を信号光の偏）を状態に一致させる
ことができる。すなわＣ）、！＠２図で示した手順と逆
の手順で直線偏光の楕円偏光ｆ？、、楕円偏光の主軸の
回転を行えばよい。素子の具体例としては、従来技術と
同じく。Is the output of a local light source generally direct? 8 polarized light, for example,
By controlling the phase difference using a birefringent material having a crystal axis that makes an angle of 45 degrees with the polarization direction, an ellipse m) i: (however, the direction of the principal axis is different) that is the same as that of the signal light is created. Subsequently, by controlling the second birefringent material and rotating the CC line axis, it is possible to match the polarization state of the single light beam with the polarization state of the signal light. Sunawa C),! @2 Obtain elliptically polarized light f? of linearly polarized light by reversing the procedure shown in the figure. ,, the principal axis of the elliptically polarized light may be rotated. The specific example of the element is the same as the conventional technology.
バビネールイユの補償版、甫気−光学変調器、半波長板
、澗彼面回転素子などを用いることができ、これらを組
み曾わせて偏光変−器１０が構成できる。A compensating version of Babine-l'oeil, an air-optical modulator, a half-wave plate, a transverse rotation element, etc. can be used, and the polarization converter 10 can be constructed by combining these.
本装置においては、光検波器に入力する信号光および局
発光電力が。In this device, the signal light and local light power input to the photodetector are
Ｐ ＝α ｐ −−−−−−−−−−−−−−＠ηｓ
ｍｓｓ。P = α p −−−−−−−−−−−−−@ηs
mss.
Ｐ ＝α′α ｐ −−−−−−−−−−−−（イ）−
ｅ ｃ ｍ、４；３ＡＯ−″
で与えられる。ここで、α６ は２個の複屈折性物質か
ら成る偏光変調器１０の挿入損である。したがって、局
発光電力が十分に大きい場合、光検波器のに気信号眠力
、ａａｆ−電力、ＳＮ比は。P = α′α p −−−−−−−−−−−−(a)−
e cm,4;3AO-'', where α6 is the insertion loss of the polarization modulator 10 made of two birefringent materials.Therefore, if the local light power is sufficiently large, the optical detection What is the signal sleep power, AAF-power, and signal-to-noise ratio of the instrument?
Ｐ ＝＝ ２ＫＤ２α゛３αｍ８αｍｆｆｌＰｓｏＰ−
ｇｏ −−−−−”で与えられ、［＝ｌである。式（２
５）を式（８） 、 ＋１１）と比較すれば明らかなよ
うに、本受信装置では、偏波制御を行なうことによる伺
らの新しい８Ｎ比劣化を伴うことなく、偏波状態の不整
合に起因するＳＮ比劣化を除去することができる。これ
は。P == 2KD2α゛3αm8αmfflPsoP-
go ------'', and [=l. Equation (2
As is clear from comparing 5) with Equations (8) and +11), this receiver can handle polarization state mismatch without deteriorating the 8N ratio due to polarization control. The resulting SN ratio deterioration can be removed. this is.
十分に電力が大きな局発光の偏光状態を制御しているた
めである。This is because the polarization state of local light with sufficiently high power is controlled.
以上説明したように、この発明に係る光受信装置は、局
発光の偏光状態を制御して、信号光の偏光状態に一致さ
せることによって、偏光状態の差異によるＳＮ比劣化を
除去することができ、しかも、従来装置に見られたよう
な偏波制御に伴う新しいＳＮ比劣化も除去することがで
きる。さらに。As explained above, the optical receiving device according to the present invention can eliminate the deterioration of the SN ratio due to the difference in the polarization state by controlling the polarization state of the local light to match the polarization state of the signal light. Moreover, it is also possible to eliminate the new SN ratio deterioration caused by polarization control, which was observed in conventional devices. moreover.
偏光状態の制御素子として従来装置と同一の素子を用い
ることができるので、従来装置と同程度の応答速度が実
現できる。Since the same element as the conventional device can be used as the polarization state control element, a response speed comparable to that of the conventional device can be achieved.
したがって、光ベテロダイン検波方式な・どにおいて受
信信号電力が信号光の偏光状態に依存するような場合に
１本発明による光受信装置を用いれば、高性能な伝送方
式が実現できるとともに、光伝送路として使用する光フ
ァイバの偏光特性に対する要求条件が緩和できる。Therefore, when the received signal power depends on the polarization state of the signal light in the optical beterodyne detection method, etc., if the optical receiver according to the present invention is used, a high-performance transmission method can be realized, and the optical transmission line The requirements for the polarization characteristics of the optical fiber used as an optical fiber can be relaxed.
第１図は従来の光受信装置の構成図、第２図は偏波匍制
御の説明図、第３図は本発明装置の構成図である。
１・・・・・・光ファイバ、２・・・・・・偏光補償回
路、３・・・・・・分波器、４・・・・・・偏光検出回
路、５・旧・・局発光源、６・・・・・・合波器、７・
・・・・・光検波器、訃・団・信号処理回路、９・・・
・・・信号出力端子、１ｏ・旧・・偏光変調器。
１工・・・・・・信号処理回路。
出願人 日本直信電話公社FIG. 1 is a block diagram of a conventional optical receiver, FIG. 2 is an explanatory diagram of polarization control, and FIG. 3 is a block diagram of the apparatus of the present invention. 1... Optical fiber, 2... Polarization compensation circuit, 3... Demultiplexer, 4... Polarization detection circuit, 5... Old local light source. source, 6... multiplexer, 7.
...Photodetector, signal processing circuit, 9...
...Signal output terminal, 1o, old...Polarization modulator. 1 engineering...Signal processing circuit. Applicant: Japan Direct Telephone Public Corporation
Claims (1)
光検波して信号を得る光受信装置において、信号光と局
発光を合成する合波器と１合成された光を検波する光検
波器と、光検波器からの出力を処理する信号処理回路と
、前記局発光源と合波器の間に挿入されて前記信号処理
回路の出力が最大となるように局発光の偏光状態を変化
させる偏光変調器とを備えたことを特徴とする光受信装
置。In an optical receiving device that obtains a signal by optically detecting the signal light input from the optical transmission line using the local light of a single local light source, a multiplexer that combines the signal light and the local light and one that detects the combined light. A photodetector, a signal processing circuit that processes the output from the photodetector, and a polarization state of the local light inserted between the local light source and the multiplexer so that the output of the signal processing circuit is maximized. An optical receiving device characterized by comprising: a polarization modulator that changes the polarization modulator.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58229649A JPS60121424A (en) | 1983-12-05 | 1983-12-05 | Optical receiver |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58229649A JPS60121424A (en) | 1983-12-05 | 1983-12-05 | Optical receiver |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPS60121424A true JPS60121424A (en) | 1985-06-28 |
Family
ID=16895502
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58229649A Pending JPS60121424A (en) | 1983-12-05 | 1983-12-05 | Optical receiver |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS60121424A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61153616A (en) * | 1984-12-27 | 1986-07-12 | Kokusai Denshin Denwa Co Ltd <Kdd> | Polarization matching device |
| JPH01108534A (en) * | 1987-09-28 | 1989-04-25 | Philips Gloeilampenfab:Nv | Optical type heterodyne or homodyne detector for optical signal beam |
| JPH02294617A (en) * | 1989-04-17 | 1990-12-05 | Tektronix Inc | Polarization controller |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56150731A (en) * | 1980-04-23 | 1981-11-21 | Nippon Telegr & Teleph Corp <Ntt> | Optical polarization matching and combining device |
-
1983
- 1983-12-05 JP JP58229649A patent/JPS60121424A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS56150731A (en) * | 1980-04-23 | 1981-11-21 | Nippon Telegr & Teleph Corp <Ntt> | Optical polarization matching and combining device |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS61153616A (en) * | 1984-12-27 | 1986-07-12 | Kokusai Denshin Denwa Co Ltd <Kdd> | Polarization matching device |
| JPH01108534A (en) * | 1987-09-28 | 1989-04-25 | Philips Gloeilampenfab:Nv | Optical type heterodyne or homodyne detector for optical signal beam |
| JPH02294617A (en) * | 1989-04-17 | 1990-12-05 | Tektronix Inc | Polarization controller |
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