JPH0357448B2 - - Google Patents
Info
- Publication number
- JPH0357448B2 JPH0357448B2 JP56042221A JP4222181A JPH0357448B2 JP H0357448 B2 JPH0357448 B2 JP H0357448B2 JP 56042221 A JP56042221 A JP 56042221A JP 4222181 A JP4222181 A JP 4222181A JP H0357448 B2 JPH0357448 B2 JP H0357448B2
- Authority
- JP
- Japan
- Prior art keywords
- waveguide
- light
- mode light
- branch
- line
- 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
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/293—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means
- G02B6/29344—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals with wavelength selective means operating by modal interference or beating, i.e. of transverse modes, e.g. zero-gap directional coupler, MMI
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/10—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type
- G02B6/12—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings of the optical waveguide type of the integrated circuit kind
- G02B6/13—Integrated optical circuits characterised by the manufacturing method
- G02B6/134—Integrated optical circuits characterised by the manufacturing method by substitution by dopant atoms
- G02B6/1342—Integrated optical circuits characterised by the manufacturing method by substitution by dopant atoms using diffusion
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
- G02B6/24—Coupling light guides
- G02B6/26—Optical coupling means
- G02B6/28—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals
- G02B6/2804—Optical coupling means having data bus means, i.e. plural waveguides interconnected and providing an inherently bidirectional system by mixing and splitting signals forming multipart couplers without wavelength selective elements, e.g. "T" couplers, star couplers
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Engineering & Computer Science (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Optical Integrated Circuits (AREA)
Description
【発明の詳細な説明】
本発明は、光導波路におけるモード・フイルタ
ー、特に光導波路における伝播光の低次高次のモ
ード分離を簡易にかつ低損失で行なうモード・フ
イルターに関する。DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a mode filter in an optical waveguide, and particularly to a mode filter that easily performs low-order and high-order mode separation of propagating light in an optical waveguide with low loss.
光導波路において、いかなる光が導波されるか
は、該導波路の幅および深さ等導波路構造及び導
波路の屈折率プロフイルによつて決定される。本
願の発明者は、基本モード光を伝播するだけでな
く、基本モード光だけが導波できる導波路の境界
より若干広い範囲において、基本モードだけでな
くその他のモードも立たせうる光導波路について
研究を進めてきた。かかる研究の経過において、
従来技術による光導波路においては、低次（基
本）、高次のモードを選択的に分離し利用しうる
モード分離器は容易には構成できず、例えば基本
モード光のみが伝播している光導波路を得るため
には、最初から基本モード光しか伝播しない光導
波路が用いられていることに注目した。 What kind of light is guided in an optical waveguide is determined by the waveguide structure such as the width and depth of the waveguide and the refractive index profile of the waveguide. The inventor of this application has conducted research on optical waveguides that can not only propagate fundamental mode light but also allow other modes to propagate in a slightly wider range than the boundaries of the waveguide where only fundamental mode light can be guided. I've made progress. In the course of such research,
In conventional optical waveguides, it is not easy to construct a mode separator that can selectively separate and utilize low-order (fundamental) and high-order modes; for example, in optical waveguides in which only fundamental mode light propagates, In order to obtain this, we focused on the fact that an optical waveguide that only propagates fundamental mode light is used from the beginning.
ところで、光導波路中に形成された機能素子の
中には、基本モード光に対してのみ有効に使用す
るものがあり、高次モード光が混入していると機
能素子の特性劣化のおそれがあり、この場合高次
モード光を選択的に分離除去する必要がある。前
記した如く、従来技術においてこのような容易な
方法による高次モード光の選択的分離除去は未だ
知られていない。 By the way, some functional elements formed in optical waveguides are effective only for fundamental mode light, and if higher-order mode light is mixed in, there is a risk of deterioration of the characteristics of the functional element. In this case, it is necessary to selectively separate and remove higher-order mode light. As mentioned above, selective separation and removal of higher-order mode light using such an easy method is not yet known in the prior art.
本発明の目的は、基本モード光とその他の高次
モード光が同時に伝播しうる構造の光導波路にお
いて、基本モード光と高次モード光とを分離する
にある。その目的を達成するために、本発明によ
ると、屈折率n0の電気光学結晶基板面に、屈折率
n0より大きい屈折率n1を付与するための材料が熱
拡散されて形成された光導波路を有し、該光導波
路は主入力光線路と分岐導波線路が交叉角を１〜
3°として交叉した略Ｘ形状からなると共に、該交
叉部分の導波路幅が該主入力光線路と該分岐導波
線路の導波路幅より広く形成されており、該主入
力光線路を伝播する光線の基本モード光と高次モ
ード光成分を選択的に分離し該主入力光線路と該
分岐導波線路に別々に導波させるものである。 An object of the present invention is to separate fundamental mode light and higher order mode light in an optical waveguide having a structure in which fundamental mode light and other higher order mode light can propagate simultaneously. In order to achieve that objective, according to the present invention, a refractive index
It has an optical waveguide formed by thermally diffusing a material for imparting a refractive index n 1 larger than n 0 , and the optical waveguide has a main input optical line and a branch waveguide whose intersection angle is 1 to 1.
The waveguide has a substantially X shape that intersects at an angle of 3°, and the waveguide width at the intersection is wider than the waveguide width of the main input optical line and the branch waveguide, and the waveguide propagates through the main input optical line. The fundamental mode light and higher-order mode light components of the light beam are selectively separated and guided separately to the main input optical line and the branch waveguide.
以下、本発明の実施例を添付図面を参照して説
明する。 Embodiments of the present invention will be described below with reference to the accompanying drawings.
本願の発明者は屈折率n0の電気光学結晶である
LiNbO3基板に、屈折率n0より大きい屈折率n1を
付与するためTiを熱拡散させる方法で交叉光導
波路を作成し、その光伝播特性を詳細に調べた
所、まず線路が基本モード光だけが伝播可能であ
る線路から構成される交叉導波路に於いては、交
叉角、屈折率変化△ｎ等を適当に選択する事によ
り、光をほとんど分岐側に屈曲して導波させる事
が可能である事を知つた。このような現象の起き
る原因は交叉部で導波路幅が、それより導出する
導波線路の導波路幅より結果的に広くなつている
ため、導波されてきた光の許容されるモード数が
交叉部で増加し、また交叉部における屈折率変化
△n1が導波線路の屈折率変化△n2より大きくな
り、該交叉部で導波光が蛇行が発生することが原
因であると解される。 The inventor of this application is an electro-optic crystal with a refractive index n 0
A crossed optical waveguide was created on a LiNbO 3 substrate by thermally diffusing Ti to give it a refractive index n 1 larger than n 0 , and its optical propagation characteristics were investigated in detail. In a crossed waveguide consisting of a line that can only propagate, by appropriately selecting the crossing angle, refractive index change △n, etc., it is possible to bend most of the light toward the branching side and guide it. I learned that it is possible. The reason why this phenomenon occurs is that the waveguide width at the intersection is wider than the waveguide width of the waveguide line leading out from the intersection, so the number of modes allowed for the guided light is limited. This is understood to be due to the fact that the refractive index change △n 1 at the intersection is larger than the refractive index change △n 2 of the waveguide, and that the guided light meandering occurs at the intersection. Ru.
一方この導波路と同じ作成方法で屈折率△ｎを
少し増加させる、または幅をわずかに増加させる
等の手段で直線導波路を基本モード光以外の光も
導波可能なものとしこのマルチモード直線導波路
から構成される交叉導波路を作成してその導波特
性を調べた所伝播する光のモード状態により主線
路、分岐線路への光の伝播特性が大きく変化し
た。このように交叉導波路では作成方法により伝
播状態のわずかな変化で光の進路をふり分ける事
が可能である。一方伝播が交叉部でも基本モード
的であるほど光の直進性が強くなる事が確かめら
れた。 On the other hand, by using the same manufacturing method as this waveguide to slightly increase the refractive index △n or slightly increase the width, the linear waveguide can be made to be able to guide light other than the fundamental mode light, and this multi-mode straight line is created. When we created a cross-over waveguide consisting of waveguides and investigated its waveguide characteristics, we found that the propagation characteristics of light to the main line and branch line changed greatly depending on the mode state of the propagating light. In this way, in a crossed waveguide, depending on the method of fabrication, it is possible to divide the path of light with a slight change in the propagation state. On the other hand, it was confirmed that the more fundamental mode-like the propagation is, even at the intersection, the stronger the straightness of light becomes.
かかる低次モード光の直進性に注目して、本願
の発明者は、前記した如く光導波路中に交叉構造
を形成し、高次モード光を分岐させ分岐路に導く
についての実験を重ね所期の目的を達成した。 Focusing on the straightness of such low-order mode light, the inventor of the present application formed a crossing structure in the optical waveguide as described above, and conducted experiments to branch the high-order mode light and guide it to a branch path. achieved its purpose.
第１図以下を参照すると、リチウムナイオベー
ト（LiNb3）基板１にレジスト膜２を塗布し、そ
れをパターニングし（第１図）、レジスト膜を除
去した部分３′，４′を通してチタン（Ti）５を
蒸着しレジスタ部をリフトオフしてTiパターン
を作り、例えば空気中982℃で５時間熱拡散して、
交叉部Ａを有する主入力光線路３と分岐導波線路
４を形成する（第２図）。なお、これらの図にお
いて、主入力光線路３と分岐導波線路４との交叉
状態は誇張的に示される。 Referring to Figure 1 and subsequent figures, a resist film 2 is applied to a lithium niobate (LiNb 3 ) substrate 1, patterned (Fig. 1), and titanium (Ti ) 5 is vapor-deposited, the resistor part is lifted off to create a Ti pattern, and heat diffusion is performed for 5 hours at 982°C in air, for example.
A main input optical line 3 and a branch waveguide line 4 having an intersection A are formed (FIG. 2). In addition, in these figures, the crossing state of the main input optical line 3 and the branch waveguide line 4 is shown exaggeratedly.
主入力光線路３、分岐導波線路４はいずれもそ
の導波路幅Ｂが第３図の断面図に示される如きも
のであるが、交叉部Ａは両線路３，４が交叉する
関係でその導波路幅が広くなり、結果的に害交叉
部Ａの△n1両線路３，４の△n2より大きくなる。
この実施例において、チタン５はその厚さを400
〔Å〕に、幅を約10〔μｍ〕にとり、形成される
Ti拡散層６は、深さ数〔μｍ〕の交叉部Ａを有
する主入力光線路３と分岐導波線路４を構成す
る。 The main input optical line 3 and the branch waveguide line 4 both have a waveguide width B as shown in the cross-sectional view of FIG. The waveguide width becomes wider, and as a result, △n 1 of the noxious intersection A becomes larger than △n 2 of both lines 3 and 4.
In this example, titanium 5 has a thickness of 400
[Å] with a width of approximately 10 [μm].
The Ti diffusion layer 6 constitutes the main input optical line 3 and the branch waveguide line 4, each having an intersection A with a depth of several μm.
上記の如き構造の交叉導波路の実用例は第４図
の平面図に示され、図において矢印７は励起され
た光、矢印８はマルチ・モード光、矢印９はシン
グル・モード光、矢印１０は高次モード光を、１
１は機能素子を示し、主入力光線路３と分岐導波
線路４の交叉状態は誇張して示されるが、その交
叉角θは１〜3°である。 A practical example of a crossed waveguide having the above structure is shown in the plan view of FIG. 4, in which arrow 7 indicates excited light, arrow 8 indicates multi-mode light, arrow 9 indicates single-mode light, and arrow 10 indicates excited light. is the higher mode light, 1
Reference numeral 1 indicates a functional element, and the crossing state between the main input optical line 3 and the branch waveguide line 4 is exaggerated, but the crossing angle θ is 1 to 3 degrees.
かかる交叉導波路に波長0.633〔μｍ〕の光を励
起し（矢印７）、その出力をNFパターン（Near
Field Pattern）で観察したところ、低次モード
光は交叉部の構造によりその進路が曲げられるこ
とがきわめて少ない事実が確認された。 Light with a wavelength of 0.633 [μm] is excited into the crossed waveguide (arrow 7), and the output is converted into an NF pattern (Near
Field Pattern), it was confirmed that the path of low-order mode light is extremely rarely bent by the structure of the intersection.
従つて、上述の如くシングル・モード光を必要
とする機能素子１１の前方に分岐導波線路４を形
成すると、分岐導波線路４は交叉フイルターとし
て働らき、低次モード光（基本モード光）が選択
的に透過されて機能素子１１に達し、また一方高
次モード光は分岐導波線路４に分岐誘導され、積
極的に利用する事ができる。 Therefore, when the branch waveguide line 4 is formed in front of the functional element 11 that requires single-mode light as described above, the branch waveguide line 4 acts as a cross filter, and the branch waveguide line 4 acts as a cross filter to transmit low-order mode light (fundamental mode light). is selectively transmitted and reaches the functional element 11, while higher-order mode light is branched and guided to the branch waveguide line 4 and can be actively used.
第１図ないし第３図は本願発明の実施例の製造
工程を示す図、第４図は本願発明の実施例を示す
平面図である。
１……LiNbO3基板、３……主入力光線路、４
……分岐導波線路、５……Ti、６……Ti拡散層、
７……励起された光、８……マルチ・モード光、
９……シングル・モード光、１０……高次モード
光、１１……機能素子。
1 to 3 are diagrams showing manufacturing steps of an embodiment of the present invention, and FIG. 4 is a plan view showing an embodiment of the present invention. 1...LiNbO 3 substrate, 3...Main input optical line, 4
...Branch waveguide, 5...Ti, 6...Ti diffusion layer,
7...Excited light, 8...Multi-mode light,
9...Single mode light, 10...Higher mode light, 11...Functional element.
Claims (1)
より大きい屈折率n1を付与するための材料が熱拡
散されて形成された光導波路を有し、該光導波路
は主入力光線路と分岐導波線路が交叉角を１〜3°
として交叉した略Ｘ形状からなると共に、該交叉
部分の導波路幅が該主入力光線路と該分岐導波線
路の導波路幅より広く形成されており、該主入力
光線路を伝播する光線の基本モード光と高次モー
ド光成分を選択的に分離し該注入力光線路と該分
岐導波線路に別々に導波させることを特徴とする
光導波路のモード・フイルター。1 On the surface of the electro-optic crystal substrate with refractive index n 0 , refractive index n 0
It has an optical waveguide formed by thermally diffusing a material to give a larger refractive index n 1 , and the optical waveguide has an intersection angle of 1 to 3 degrees between the main input optical line and the branch waveguide.
The width of the waveguide at the crossing portion is wider than the waveguide width of the main input optical line and the branch waveguide, and the waveguide width of the crossing portion is wider than the waveguide width of the main input optical line and the branch waveguide. A mode filter for an optical waveguide, characterized in that a fundamental mode light and a higher-order mode light component are selectively separated and guided separately to the input optical line and the branch waveguide.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4222181A JPS57157209A (en) | 1981-03-23 | 1981-03-23 | Mode filter for optical waveguide |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP4222181A JPS57157209A (en) | 1981-03-23 | 1981-03-23 | Mode filter for optical waveguide |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPS57157209A JPS57157209A (en) | 1982-09-28 |
| JPH0357448B2 true JPH0357448B2 (en) | 1991-09-02 |
Family
ID=12629978
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP4222181A Granted JPS57157209A (en) | 1981-03-23 | 1981-03-23 | Mode filter for optical waveguide |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPS57157209A (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5173394B2 (en) | 2007-12-21 | 2013-04-03 | パナソニック株式会社 | Optical device |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS5343304A (en) * | 1976-09-30 | 1978-04-19 | Mitsubishi Electric Corp | Vehicle number detecting system |
-
1981
- 1981-03-23 JP JP4222181A patent/JPS57157209A/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| JPS57157209A (en) | 1982-09-28 |
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