JPH0114567B2 - - Google Patents
Info
- Publication number
- JPH0114567B2 JPH0114567B2 JP58166869A JP16686983A JPH0114567B2 JP H0114567 B2 JPH0114567 B2 JP H0114567B2 JP 58166869 A JP58166869 A JP 58166869A JP 16686983 A JP16686983 A JP 16686983A JP H0114567 B2 JPH0114567 B2 JP H0114567B2
- Authority
- JP
- Japan
- Prior art keywords
- light
- polarized
- separated
- modulated
- polarized light
- 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
Links
- 230000003287 optical effect Effects 0.000 claims description 19
- 230000010287 polarization Effects 0.000 claims description 16
- 238000004891 communication Methods 0.000 claims description 10
- 239000000835 fiber Substances 0.000 claims description 8
- 238000000034 method Methods 0.000 claims description 4
- 238000001514 detection method Methods 0.000 claims description 3
- 230000000694 effects Effects 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 238000004519 manufacturing process Methods 0.000 description 2
- 230000010355 oscillation Effects 0.000 description 2
- 238000000926 separation method Methods 0.000 description 2
- 238000007796 conventional method Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 238000002347 injection Methods 0.000 description 1
- 239000007924 injection Substances 0.000 description 1
- 230000006903 response to temperature Effects 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/60—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)
- Optical Communication System (AREA)
Description
【発明の詳細な説明】
(a) 発明の技術分野
本発明は安価に構成出来るヘテロダイン光通信
方式に関する。Detailed Description of the Invention (a) Technical Field of the Invention The present invention relates to a heterodyne optical communication system that can be constructed at low cost.
(b) 技術の背景
ゼーマンレーザは磁場の強さによるエネルギー
レベルの分離の大きさｇ・μ・Ｈ（但しｇは
gfactor、μは磁気能率、Ｈは磁界の強さ）だけ
波長の違う２つの光を出力する。又この２つの光
の一方は右円偏波であり他方は左円偏波である。
又、各光が発生するためのエネルギーレベルの差
は、通常の温度変化範囲内では一定であり、従つ
ての差は一定である。(b) Background of the technology Zeeman lasers are based on the magnitude of energy level separation g・μ・H depending on the strength of the magnetic field (where g is
It outputs two lights with different wavelengths by gfactor, μ is the magnetic efficiency, and H is the strength of the magnetic field. Also, one of these two lights is right-handed circularly polarized, and the other is left-handed circularly polarized.
Also, the difference in energy level for each light to be generated is constant within a normal temperature change range, and therefore the difference is constant.
(c) 従来技術と問題点
ヘテロダイン光通信方式においては、中間周波
数を一定に保つために発振器及び局部発振器の周
波数の安定化が非常に困難な問題である。この周
波数を安定化するには、従来発振器及び局部発振
器の温度を温度変動巾1/100度程度の精密な制御
を行う方法又は光注入同期法が用いられている。(c) Prior art and problems In the heterodyne optical communication system, it is extremely difficult to stabilize the frequencies of the oscillator and local oscillator in order to keep the intermediate frequency constant. To stabilize this frequency, conventional methods have been used in which the temperatures of the oscillator and local oscillator are precisely controlled within a temperature fluctuation range of about 1/100 degree, or an optical injection locking method is used.
しかし、前者は複雑な電子回路を必要とし、後
者は光学系の調整が困難で製作歩留りが悪い。 However, the former requires a complicated electronic circuit, and the latter has a difficult manufacturing yield because it is difficult to adjust the optical system.
従つていづれの方法を用いてもヘテロダイン光
通信方式は高価になる欠点がある。 Therefore, no matter which method is used, the heterodyne optical communication system has the drawback of being expensive.
(d) 発明の目的
本発明の目的は上記の欠点に鑑み、安価に構成
出来るヘテロダイン光通信方式の提供にある。(d) Object of the Invention In view of the above drawbacks, the object of the present invention is to provide a heterodyne optical communication system that can be constructed at low cost.
(e) 発明の構成
本発明は上記の目的を達成するために、ゼーマ
ンレーザの右円偏波及び左円偏波の２つの光の発
振波長に差があり、温度が変動してもこの波長差
は殆ど変化しない点に着目したものであり、ゼー
マンレーザからの右円偏波及び左円偏波の出力光
をλ／４板（λは波長）を通し直交した直線偏波
とし、該直交した直線偏波された光を第１の偏光
子を用いて分離し、分離された一方の光を外周周
波数変調器で変調した後、分離された他方の光と
合成し、単一モード定偏波フアイバに入射し、該
単一モード定偏波フアイバからの出力光を再び第
２の偏光子で分離し、分離されたいずれか一方の
偏光に対しλ／２板を通し他方の偏光と偏波面を
合わせるとともに変調されていない方の偏光を光
増幅器で増幅し、変調されている方の偏光と変調
されていない方の偏光とを合成し、受光器に入射
することによりヘテロダイン検波を行うことを特
徴とする。(e) Structure of the Invention In order to achieve the above object, the present invention has a difference in the oscillation wavelength of the right-handed circularly polarized light and the left-handed circularly polarized light of the Zeeman laser, and even when the temperature changes, this wavelength remains unchanged. Focusing on the point that the difference hardly changes, the right-handed circularly polarized wave and left-handed circularly polarized output light from the Zeeman laser are made into orthogonal linearly polarized waves through a λ/4 plate (λ is the wavelength). The linearly polarized light is separated using a first polarizer, one of the separated lights is modulated by an outer frequency modulator, and then combined with the other separated light to produce a single mode constant polarization. The output light from the single mode polarization fixed fiber is separated again by a second polarizer, and one of the separated polarized lights is passed through a λ/2 plate and then polarized with the other polarized light. Heterodyne detection is performed by aligning the wavefronts, amplifying the unmodulated polarized light with an optical amplifier, combining the modulated polarized light with the unmodulated polarized light, and inputting the combined light into a photoreceiver. It is characterized by
本発明によれば、波長差が温度変動に対し一
定、即ち、周波数差が一定となるため、一方の光
を局部発振用に他方の光を信号変調用に用い、中
間周波数の安定化が可能となる。 According to the present invention, since the wavelength difference remains constant despite temperature fluctuations, that is, the frequency difference remains constant, it is possible to stabilize the intermediate frequency by using one light for local oscillation and the other for signal modulation. becomes.
(f) 発明の実施例
以下本発明の一実施例につき図に従つて説明す
る。(f) Embodiment of the invention An embodiment of the invention will be described below with reference to the drawings.
図は本発明の実施例のヘテロダイン光通信方式
のブロツク図である。 The figure is a block diagram of a heterodyne optical communication system according to an embodiment of the present invention.
図中１はゼーマンレーザ、２はλ／４板、３，
３′は偏光子、４は外部変調器、５は単一モード
定偏波フアイバ、６，６′，６″，６はミラー、
７，７′はハーフミラー、８はλ／２板、９は光
増巾器を示す。 In the figure, 1 is a Zeeman laser, 2 is a λ/4 plate, 3,
3' is a polarizer, 4 is an external modulator, 5 is a single mode polarization constant fiber, 6, 6', 6'', 6 is a mirror,
7 and 7' are half mirrors, 8 is a λ/2 plate, and 9 is an optical amplifier.
ゼーマンレーザ１から右円偏波（波長λ1）及び
左円偏波（波長λ2）の光が出力されている。これ
らの光をλ／４板（λは波長）２を通して２つの
直交する直線偏波にする。 The Zeeman laser 1 outputs right-handed circularly polarized light (wavelength λ 1 ) and left-handed circularly polarized light (wavelength λ 2 ). These lights are converted into two orthogonal linearly polarized waves through a λ/4 plate (λ is wavelength) 2.
その後偏光子３を用いて２偏波を分離し、一方
の偏光はミラー６を介して外部変調器４に入力、
位相もしくは周波数変調する。この外部変調器４
による変調は、例えば媒質TeO2やPbM0O4等の
電気光学効果を用いるとか音響光学効果を用いて
変調する。他方の偏光はミラー６′を介し、外部
変調器４で変調された光と、バツクミラー７′に
て合成し、伝送路である単一モード定偏波フアイ
バ５に入射する。 After that, the polarizer 3 is used to separate the two polarized waves, and one polarized light is input to the external modulator 4 via the mirror 6.
Modulate phase or frequency. This external modulator 4
The modulation is carried out using, for example, the electro-optic effect of a medium such as TeO 2 or PbM 0 O 4 or the acousto-optic effect. The other polarized light passes through a mirror 6' and is combined with the light modulated by the external modulator 4 at a back mirror 7', and enters the single mode polarization fiber 5, which is a transmission path.
単一モード定偏波フアイバ５を出た光は再び偏
光子３′にて分けられ変調されていない偏光は
λ／２板８で90度偏光方向を回転し、変調されて
いる方の偏光と偏波面を合し、光増巾器９で強度
を増加し、ミラー６″，６を介した変調されて
いる方の偏光と、ハーフミラー７′にて合成し、
受光器１０に入射してヘテロダイン検波を行う。 The light exiting the single mode polarization fiber 5 is separated again by the polarizer 3', and the unmodulated polarized light is rotated by 90 degrees by the λ/2 plate 8, and is separated from the modulated polarized light. The planes of polarization are combined, the intensity is increased by an optical amplifier 9, and the polarized light which has been modulated via mirrors 6'' and 6 is combined by a half mirror 7'.
The light enters the photoreceiver 10 and performs heterodyne detection.
上記実施例では、変調されない偏光は、偏光子
３からミラー６′、ミラー７、単一モード定偏波
フアイバ５、偏光子３′、ミラー６″、ミラー６
を介し、外部変調器４で変調された偏光は、ミラ
ー７、偏光子３′λ／２板８、光増幅器９を介し
てミラー７′にて合成する例で示した。ここで、
偏光子３及び３′の偏光分離方向は互いに異なる
もので示してあるが、同一のものを使用した場合
には、変調されない偏光が透過方向となるため、
光増幅器９はミラー６″とミラー６との間に置
かれることになる。 In the above embodiment, unmodulated polarized light is transmitted from polarizer 3 to mirror 6' to mirror 7 to single mode polarization fixed fiber 5 to polarizer 3' to mirror 6'' to mirror 6.
An example is shown in which the polarized light modulated by the external modulator 4 is synthesized by the mirror 7' via the mirror 7, the polarizer 3', the λ/2 plate 8, and the optical amplifier 9. here,
Although the polarizers 3 and 3' are shown with different polarization separation directions, if the same polarizers are used, the unmodulated polarized light will be in the transmission direction.
The optical amplifier 9 will be placed between the mirrors 6''.
また、上記実施例では、変調されていない偏光
の偏波面を変調されている偏光の偏波面に合わせ
る例で説明したが、この逆の場合、即ち、変調さ
れている偏光の偏波面を変調されていない偏光の
偏波変に合わせるものであつてもよい。その場合
には、λ／２板８をミラー６″とミラー６との
間に設けることになるが、何れに合わせるかは、
本発明の本質ではない。 Furthermore, in the above embodiment, the polarization plane of unmodulated polarized light is adjusted to the polarization plane of modulated polarized light, but in the opposite case, that is, the polarization plane of modulated polarized light is It may be adapted to the change in polarization of polarized light. In that case, the λ/2 plate 8 will be provided between the mirrors 6'', but which one to match will depend on
This is not the essence of the invention.
以上のようにすることによりゼーマンレーザ１
の温度を特に制御する必要もなく、又レーザとし
てはゼーマンレーザ１のみでヘテロダイン光通信
方式が構成出来かつ発光側受光側共特別な光学的
調整も不要で製作上の歩留りもなく安価にヘテロ
ダイン光通信方式が構成出来る。 By doing the above, Zeeman laser 1
There is no need to particularly control the temperature of the laser, and a heterodyne optical communication system can be configured using only the Zeeman laser 1. No special optical adjustment is required for both the light emitting and light receiving sides, and there is no manufacturing yield and the heterodyne light can be produced at low cost. Communication method can be configured.
(g) 発明の効果
以上詳細に説明せる如く本発明によれば、安定
した中間周波数を得るに当たり、ゼーマンレーザ
の右円偏波と左円偏波の２つの光の波長差は、温
度変動に対し一定であるため、回路における温度
変化に対しレーザの温度は特に制御する必要もな
く又レーザは１個でよくかつ特別な光学的調整も
不要であるので、安価にヘテロダイン光通信方式
が構成出来る効果がある。(g) Effects of the Invention As explained in detail above, according to the present invention, in obtaining a stable intermediate frequency, the wavelength difference between the right-handed circularly polarized wave and the left-handed circularly polarized wave of the Zeeman laser is On the other hand, since it is constant, there is no need to particularly control the laser temperature in response to temperature changes in the circuit, and only one laser is required, and no special optical adjustment is required, so a heterodyne optical communication system can be constructed at low cost. effective.
図面は本発明のヘテロダイン光通信方式のブロ
ツク図である。
図中１はゼーマンレーザ、２はλ／２板、３，
３′は偏光子、４は外部変調器、５は単一モード
定偏波フアイバ、６，６′，６″，６はミラー、
７，７′はハーフミラー、８はλ／２板、９は光
増巾器、１０は受光器を示す。
The drawing is a block diagram of the heterodyne optical communication system of the present invention. In the figure, 1 is a Zeeman laser, 2 is a λ/2 plate, 3,
3' is a polarizer, 4 is an external modulator, 5 is a single mode polarization constant fiber, 6, 6', 6'', 6 is a mirror,
7 and 7' are half mirrors, 8 is a λ/2 plate, 9 is an optical amplifier, and 10 is a light receiver.
Claims (1)
の出力光をλ／４板（λは波長）を通し直交した
直線偏波とし、 該直交した直線偏波された光を第１の偏光子を
用いて分離し、 分離された一方の光を外部周波数変調器で変調
した後、分離された他方の光と合成し、 単一モード定偏波フアイバに入射し、 該単一モード定偏波フアイバからの出力光を再
び第２の偏光子で分離し、 分離されたいずれか一方の偏光に対しλ／２板
を通し他方の偏光と偏波面を合わせるとともに 変調されていない方の偏光を光増幅器で増幅
し、 変調されている方の偏光と変調されていない方
の偏光とを合成し、 受光器に入射することによりヘテロダイン検波
を行うこと を特徴とするヘテロダイン光通信方式。[Claims] 1 Right-handed circularly polarized light and left-handed circularly polarized output light from a Zeeman laser are made into orthogonal linearly polarized waves through a λ/4 plate (λ is wavelength), and the orthogonally linearly polarized waves are made into orthogonal linearly polarized waves. The light is separated using a first polarizer, one of the separated lights is modulated by an external frequency modulator, and then combined with the other separated light and input into a single mode polarization fiber. The output light from the single mode polarization constant fiber is separated again by a second polarizer, and one of the separated polarized lights is passed through a λ/2 plate to match the plane of polarization with the other polarized light and is modulated. Heterodyne light is characterized by amplifying the unmodulated polarized light with an optical amplifier, combining the modulated polarized light with the unmodulated polarized light, and performing heterodyne detection by inputting the modulated light into a photoreceiver. Communication method.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58166869A JPS6057824A (en) | 1983-09-10 | 1983-09-10 | Heterodyne optical communication system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP58166869A JPS6057824A (en) | 1983-09-10 | 1983-09-10 | Heterodyne optical communication system |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS6057824A JPS6057824A (en) | 1985-04-03 |
| JPH0114567B2 true JPH0114567B2 (en) | 1989-03-13 |
Family
ID=15839139
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP58166869A Granted JPS6057824A (en) | 1983-09-10 | 1983-09-10 | Heterodyne optical communication system |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS6057824A (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4723317A (en) * | 1986-05-08 | 1988-02-02 | American Telephone And Telegraph Company, At&T Bell Laboratories | Optical heterodyne mixers providing image-frequency rejection |
| US4697284A (en) * | 1986-05-08 | 1987-09-29 | American Telephone And Telegraph Company, At&T Bell Laboratories | Single-photodiode optical heterodyne mixers |
| GB8616050D0 (en) * | 1986-07-01 | 1986-08-06 | British Telecomm | Optical local transmission system |
| US9134479B2 (en) | 2012-09-05 | 2015-09-15 | International Business Machines Corporation | Polarization diverse demultiplexing |
-
1983
- 1983-09-10 JP JP58166869A patent/JPS6057824A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS6057824A (en) | 1985-04-03 |
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