JPH02173533A - Line width measuring instrument for light spectrum - Google Patents
Line width measuring instrument for light spectrumInfo
- Publication number
- JPH02173533A JPH02173533A JP32787688A JP32787688A JPH02173533A JP H02173533 A JPH02173533 A JP H02173533A JP 32787688 A JP32787688 A JP 32787688A JP 32787688 A JP32787688 A JP 32787688A JP H02173533 A JPH02173533 A JP H02173533A
- Authority
- JP
- Japan
- Prior art keywords
- light
- optical
- delay
- optical fiber
- polarized
- 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
- 238000001228 spectrum Methods 0.000 title claims description 10
- 230000003287 optical effect Effects 0.000 claims abstract description 32
- 239000013307 optical fiber Substances 0.000 claims abstract description 30
- 230000010287 polarization Effects 0.000 claims abstract description 19
- 230000003111 delayed effect Effects 0.000 claims description 25
- 239000000835 fiber Substances 0.000 abstract description 8
- 238000000034 method Methods 0.000 description 6
- 230000000694 effects Effects 0.000 description 5
- 230000010355 oscillation Effects 0.000 description 4
- 239000004065 semiconductor Substances 0.000 description 4
- 238000005253 cladding Methods 0.000 description 3
- 230000003595 spectral effect Effects 0.000 description 3
- 230000005540 biological transmission Effects 0.000 description 2
- 230000002452 interceptive effect Effects 0.000 description 2
- 238000004891 communication Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 238000005259 measurement Methods 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 239000010453 quartz Substances 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N silicon dioxide Inorganic materials O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 238000004804 winding Methods 0.000 description 1
Landscapes
- Spectrometry And Color Measurement (AREA)
Abstract
Description
【発明の詳細な説明】
［産業上の利用分野］
本発明は、半導体レーザ等の発振スペクトル縮幅を測定
する光スペクトル線幅測定器に関するものである。DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to an optical spectral linewidth measuring device for measuring oscillation spectrum narrowing of a semiconductor laser or the like.
［従来の技術］
従来、半導体レーザの発振スペクトルを光ヘテロダイン
法を応用して測定する方法として、「半導体レーザの発
振スペクトルの新しい高分解能測定法」 ［菊池、大越
、申出、電子通信学会研究会資料、ＯＱＥ ８０−５０
． ｐ、１（１９８０）］等に示されるような遅延自己
ヘテロゲイン法が知られている。遅延自己ヘテロダイン
法とは、半導体レーザ等の被測定レーザからのレーザ光
を２つに分岐し、一方の光を遅延用光ファイバーを用い
てレーザ光のコヒーレンス時間より十分長い時間遅延さ
せ、もう一方の光（非遅延光）と合波干渉して得られた
ビート信号を計測し、そのパワースペクトルから被測定
レーザの発振スぺクトルを測定するものである。第３図
に遅延自己ヘテロダイン法を応用した光スペクトル線幅
測定器の基本的構成図を示す。光入射端より入射した被
測定用のレーザ光は、充分波器１２により２つに分岐し
、一方（遅延光）は遅延用光ファイバー１３を通過し所
定時間遅延され、もう−方（非遅延光）は遅延されずそ
のまま光合波器へ入射する。前記遅延光と非遅延光を光
合波器１５で合波し干渉せしめ、ビート信号が得られる
。１４は偏波面側ｉＩＩ機構、１６は遅延光と非遅延光
の干渉用の光路であり、１７は光出射端である。[Prior art] Conventionally, as a method for measuring the oscillation spectrum of a semiconductor laser by applying the optical heterodyne method, a new high-resolution measurement method for the oscillation spectrum of a semiconductor laser was proposed [Kikuchi, Okoshi, Kano, Institute of Electronics and Communication Engineers Research Group] Materials, OQE 80-50
．． A delayed self-heterogeneous gain method is known, such as that shown in [P. p., 1 (1980)]. The delayed self-heterodyne method is to split a laser beam from a laser to be measured such as a semiconductor laser into two, delay one beam using a delay optical fiber for a time sufficiently longer than the coherence time of the laser beam, and split the laser beam into two. The beat signal obtained by combining and interfering with light (non-delayed light) is measured, and the oscillation spectrum of the laser to be measured is measured from the power spectrum. FIG. 3 shows a basic configuration diagram of an optical spectral linewidth measuring device to which the delayed self-heterodyne method is applied. The laser beam to be measured that enters from the light input end is split into two by the wave splitter 12. One (delayed light) passes through the delay optical fiber 13 and is delayed for a predetermined time, and the other (non-delayed light) ) enters the optical multiplexer without being delayed. The delayed light and the non-delayed light are combined by an optical multiplexer 15 and interfered with each other to obtain a beat signal. 14 is a polarization plane side III mechanism, 16 is an optical path for interference between delayed light and non-delayed light, and 17 is a light output end.
［発明の解決しようとする課題］
従来は遅延用光ファイバー３にシングルモード光ファイ
バーを用いていたため、以下に示すような問題点を有し
ていた。[Problems to be Solved by the Invention] Conventionally, a single mode optical fiber was used as the delay optical fiber 3, which had the following problems.
ｌ）直線偏光の光を長距離（１００ｍ〜５ ｋｍ）のシ
ングルモード光ファイバーを通すと、偏光の方位が回転
したり、楕円偏光となったりしていた。そのため、遅延
用光ファイバーの距離によっては、遅延光と非遅延光の
偏光方向が全く異なるため、合波干渉させた場合ビート
信号が弱（なってしまう。l) When linearly polarized light is passed through a long-distance (100 m to 5 km) single mode optical fiber, the direction of the polarized light is rotated or becomes elliptically polarized light. Therefore, depending on the distance of the delay optical fiber, the polarization directions of the delayed light and the non-delayed light are completely different, so that when multiplexing and interference occurs, the beat signal becomes weak.
２）１に示した偏光方向の乱れを補正するための偏波面
制御機構１４が必要となり、従来光ファイバー型編波面
制ｉ卸装置を使用していた。該装置は遅延用光フアイバ
ー自体を適当回数巻回し、巻回してできた輪を傾けるこ
とによってファイバー内に屈折率分布をつけて雑波長板
、属波長板どして機能させるものであるが、その調整作
業が繁雑でありまた装置自体が省スペース化の妨げとな
っていた。2) A polarization plane control mechanism 14 is required to correct the disturbance in the polarization direction shown in 1, and conventionally an optical fiber type wavefront control device has been used. This device involves winding the delay optical fiber itself an appropriate number of times and tilting the resulting loop to create a refractive index distribution within the fiber to function as a coarse wavelength plate or a mixed wavelength plate. The adjustment work is complicated, and the device itself is an obstacle to space saving.
［課題を解決するための手段Ｊ
本発明は、前述の課題を解決すべくなされたものであり
、被測定用の入射光を少なくとも２つに分岐する充分波
器と、１分岐光を通過せしめる多モード光ファイバーと
、該多モード光ファイバーを通過し偏光状態がランダム
になった遅延光と他の１分岐光とを合波し干渉せしめる
光合波器とからなることを特徴とする光スペクトル線幅
測定器および被測定用の入射光を少な（とも２つに分岐
する光分波器と、１分岐光を通過せしめる多モード光フ
ァイバーと、該多モード光ファイバーを通過し偏光状態
がランダムになった遅延光と他の１分岐光とを合波し干
渉せしめる光合波器と、前記２つの分岐光の少な（とも
一方の光路に設けた光周波数シフターとからなることを
特徴とする光スペクトル線幅測定器を提供するものであ
る。[Means for Solving the Problems J] The present invention has been made to solve the above-mentioned problems, and includes a sufficient waveform device that splits incident light to be measured into at least two parts, and one branched light that passes through. Optical spectrum linewidth measurement characterized by comprising a multimode optical fiber and an optical multiplexer that combines and interferes delayed light whose polarization state has become random after passing through the multimode optical fiber and another branched light. An optical demultiplexer that splits the incident light into two (both split into two), a multimode optical fiber that allows one branched light to pass through, and delayed light that passes through the multimode optical fiber and has a random polarization state. An optical spectral linewidth measuring device comprising: an optical multiplexer for combining and interfering with one other branched light; and an optical frequency shifter provided in one of the optical paths of the two branched lights. It provides:
［作用］
本発明において、遅延用光ファイバーとして用いられる
多モード光ファイバーは、直線偏光の入射光を様々な偏
光状態の光として出射する。そのため、様々な偏光状態
の光が平均した強度で出射される。それらを非遅延光と
合波干渉させた場合、それらの非遅延光の直線偏光と同
じ偏光成分が干渉するので、合計して強度の大きいビー
ト信号が得られる。この場合、非遅延光は通常短距離の
シングルモールド光ファイバーで導光されるので、ごく
わずか偏光方向が変化しているが、遅延光がランダムな
偏光状態となっているので、上記の理由からビート信号
の強度に対する影響はない。また、前述の偏波面制御装
置が不要となるので、偏波面調整作業も省略され、省ス
ペース化も達成される。[Function] In the present invention, the multimode optical fiber used as the delay optical fiber emits linearly polarized incident light as light in various polarization states. Therefore, light in various polarization states is emitted with an average intensity. When they are combined and interfered with the non-delayed light, the same polarization components as the linearly polarized light of the non-delayed light interfere with each other, so that a beat signal with a large intensity is obtained in total. In this case, the non-delayed light is usually guided by a short distance single-molded optical fiber, so the polarization direction has changed very slightly, but the delayed light has a random polarization state, so for the reason mentioned above, there is no beat. There is no effect on signal strength. Furthermore, since the aforementioned polarization plane control device is not required, the polarization plane adjustment work is also omitted, and space saving is also achieved.
［実施例］
第１図に本発明の１実施例を示す。ｌは光入射端、２，
５はビームスプリッタ−等の光分波器と光合波器、３は
遅延用光ファイバー、６は遅延光と非遅延光の干渉用光
路、７は光出射端である。遅延用光ファイバー３として
、グレーテッドインデックス形多モード石英ファイバー
（コア径５０μｍ、クラツド径１２５μｍ、長さ１ｋｍ
）を用いて、ビート信号の強度をｌ ＯｄＢ改善できた
。多モード光ファイバーの長さとしては、伝送帯域等の
点で、グレーテッドインデックス形多モードファイバー
のコア径５０μｍ、クラツド径１２５μｍのものでは長
さ２ｋｍ以内で使用するのがよく、また、ステップイン
デックス形多モードファイバーのコア径２００μｍ、ク
ラツド径３００μｍのものでは伝送帯域が狭いので５０
ｍ以内で使用することが望ましい。１ｍ以上２ｋｍ以内
であればよい、１ｍ以下では、偏光方法がランダムにな
るのに不十分であり、２ｋｍ以上になると損失が大きく
なり好ましくない。 第２図に、遅延用光ファイバー３
の光路中に音響光学素子等の光周波数シフター８を設け
た場合の実施例を示す。他は上記実施例と同じであるが
、遅延用光ファイバーに多モード光ファイバーを用いて
いるので、同様の効果が得られた。光周波数シフター８
は、非遅延光の光路中に設けても良く、あるいは両方の
光路に設けても良い。[Example] FIG. 1 shows an example of the present invention. l is the light incidence end, 2,
Reference numeral 5 designates an optical demultiplexer and optical multiplexer such as a beam splitter, 3 an optical fiber for delay, 6 an optical path for interference between delayed light and non-delayed light, and 7 a light output end. As the delay optical fiber 3, a graded index multimode quartz fiber (core diameter 50 μm, cladding diameter 125 μm, length 1 km) was used.
), the strength of the beat signal could be improved by 1 OdB. Regarding the length of multimode optical fiber, from the viewpoint of transmission band etc., it is best to use a graded index type multimode fiber with a core diameter of 50 μm and a cladding diameter of 125 μm within 2 km; Multimode fibers with a core diameter of 200 μm and a cladding diameter of 300 μm have a narrow transmission band, so the
It is desirable to use it within m. The distance may be from 1 m to 2 km; 1 m or less is insufficient because the polarization method becomes random, and 2 km or more is not preferable because loss increases. Figure 2 shows the delay optical fiber 3.
An example will be shown in which an optical frequency shifter 8 such as an acousto-optic element is provided in the optical path. The rest is the same as the above example, but since a multimode optical fiber is used as the delay optical fiber, similar effects were obtained. Optical frequency shifter 8
may be provided in the optical path of the non-delayed light, or may be provided in both optical paths.
［発明の効果］
本発明は、遅延用光ファイバーに多モード光ファイバー
を用いているので、偏波面制御装置を設けな（でも強度
の大きいビート信号が得られるという効果を有する。ま
た、全体の構成が簡略化され、偏波面の調整作業も不要
となるという効果を有する。[Effects of the Invention] Since the present invention uses a multimode optical fiber as the delay optical fiber, it has the effect that a beat signal with high intensity can be obtained even without providing a polarization control device. This has the effect of being simplified and eliminating the need for adjustment of the plane of polarization.
第１図、第２図は本発明による光スペクトル線幅測定器
の基本的構成の平面図であり、第３図は従来例の平面図
である。
３：遅延用光ファイバー
（Ｙｌ1 and 2 are plan views of the basic configuration of the optical spectrum linewidth measuring device according to the present invention, and FIG. 3 is a plan view of a conventional example. 3: Optical fiber for delay (Yl
Claims (2)
分波器と、１分岐光を通過せしめる多モード光ファイバ
ーと、該多モード光ファイバーを通過し偏光状態がラン
ダムになった遅延光と他の１分岐光とを合波し干渉せし
める光合波器とからなることを特徴とする光スペクトル
線幅測定器。(1) An optical demultiplexer that splits the incident light to be measured into at least two parts, a multimode optical fiber that allows one branched light to pass through, and delayed light that passes through the multimode optical fiber and has a random polarization state. An optical spectrum linewidth measuring device comprising an optical multiplexer that combines and interferes with another single branch light.
分波器と、１分岐光を通過せしめる多モード光ファイバ
ーと、該多モード光ファイバーを通過し偏光状態がラン
ダムになった遅延光と他の１分岐光とを合波し干渉せし
める光合波器と、前記２つの分岐光の少なくとも一方の
光路に設けた光周波数シフターとからなることを特徴と
する光スペクトル線幅測 定器。(2) An optical demultiplexer that splits the incident light to be measured into at least two parts, a multimode optical fiber that allows one branched light to pass through, and delayed light that passes through the multimode optical fiber and has a random polarization state. An optical spectrum linewidth measuring instrument comprising: an optical multiplexer that combines and interferes with another branched light; and an optical frequency shifter provided in the optical path of at least one of the two branched lights.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32787688A JPH02173533A (en) | 1988-12-27 | 1988-12-27 | Line width measuring instrument for light spectrum |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP32787688A JPH02173533A (en) | 1988-12-27 | 1988-12-27 | Line width measuring instrument for light spectrum |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH02173533A true JPH02173533A (en) | 1990-07-05 |
Family
ID=18203967
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP32787688A Pending JPH02173533A (en) | 1988-12-27 | 1988-12-27 | Line width measuring instrument for light spectrum |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH02173533A (en) |
-
1988
- 1988-12-27 JP JP32787688A patent/JPH02173533A/en active Pending
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US6570659B2 (en) | Broadband light source system and method and light source combiner | |
| JP3989627B2 (en) | Optical gate device, method of manufacturing the device, and system including the device | |
| US5712704A (en) | Appliance for measuring polarization mode dispersion and corresponding measuring process | |
| CA2297892C (en) | Method and apparatus for the selective generation of individual photons or pairs of photons in an optical channel | |
| CN101483310B (en) | Polarization stablizing laser | |
| JP3457548B2 (en) | Polarization independent reflectometry and polarization independent reflectometer | |
| KR100258183B1 (en) | An interchannel delay-free multi-wavelength transmission type optical filter | |
| US5377284A (en) | Interferometric optical switch | |
| JP4241252B2 (en) | Optical fiber characteristic measuring apparatus and optical fiber characteristic measuring method | |
| US7382810B2 (en) | Widely-tunable laser apparatus | |
| US5647037A (en) | Optical filtering | |
| US4790655A (en) | System for measuring laser spectrum | |
| JP7181613B2 (en) | Dual optical frequency comb generation optics, laser device, measurement device | |
| JPH05248996A (en) | Wavelength dispersion measuring device for optical fiber | |
| JP2001523017A (en) | Optical wavelength converter | |
| JPH02173533A (en) | Line width measuring instrument for light spectrum | |
| US6775005B2 (en) | Low-coherence reflectometer with polarization control | |
| EP0685722A2 (en) | Method of measuring the nonlinear refractive index in a single-mode optical fibre | |
| JP2737788B2 (en) | Optical line loss distribution measuring device including optical switch | |
| US6393168B1 (en) | Method and apparatus for maintaining optical signal having low degree of polarization in specific state of polarization | |
| JPH0755571A (en) | Plarization dispersion measuring instrument | |
| JP2001075051A (en) | Discontinuous multiple wavelength light generator and polarization dispersion measurement method using the same | |
| JPH0620987Y2 (en) | Optical spectrum measuring device | |
| JPS63157133A (en) | Multiplexing circuit and separating circuit for optical pulse | |
| WO2001048541A2 (en) | Endless polarization stabilizer |