JPS62254018A - Wave guide type sensor - Google Patents

Abstract

PURPOSE:To obtain a high sensitivity compact wave guide type sensor, by a method wherein two branched wave guides are constituted of wave guides of which the refractive index and/or the temp. coefficients thereof are different from each other. CONSTITUTION:Wave guides each having a reduced number of apertures are formed by diffusing an ion having a refractive index slightly higher than that of the substrate 1 throughout said substrate 1 to be set to a branched wave guide 6 having a short light path length and a light inserting wave guide 2. Further, wave guides having an increased number of apertures are formed to the substrate by diffusing an ion generating a refractive index higher than that of the previous ion onto the substrate 1 to be set to a branched wave guide 7 having a long light path length and a coupling wave guide 5. By this constitution, loss generated when light is incident from the wave guide having a high aperture ratio to the wave guide having a low aperture ratio at the coupling part 9 of the wave guides 6, 7 can be prevented and the unbalance of the quantities of lights from the wave guides 6, 7 can be eliminated. In the branched wave guide 8, the light from the wave guide 2 can be easily branched to the wave guide 7 because the number of apertures of the wave guide 7 are more than those of the wave guide 6 and, even at the coupling part, the light of the wave guide 6 can be easily incident on the wave guide 7 in the same way.

Description

【発明の詳細な説明】 「産業上の利用分野］ 本発明は光導波路を用いたセン４Ｊに関するものである
。DETAILED DESCRIPTION OF THE INVENTION "Field of Industrial Application" The present invention relates to a sensor 4J using an optical waveguide.

［従来の技術］ 近年、無誘導性で高絶縁性というガラスファイバーの特
徴を括かした光ファイバーセンサの開発が盛／νに行な
われ−（いる。ファイバーセンサに必要イよ光学系は、
現在ファイバーとマイクロレンズ等の光学部品を組合せ
て構成されているため、ファイバーを含め／ｊ個々の部
品間の接続フラインメントが、センサの特性を決定する
ｆｆ１．要な要素になっている。これに対して、博膜尋
波技術やイオン拡散技術を利用して各部品を作製し、こ
れを一つのり板上に集積化すれば、より小型、安定で高
精度の計測が期待できる。上記の如き光導波１％ｌ！セ
ンリは光通信システム用または測定用のデバイスとして
行用であるが、−例として温度センサに用いた場合を第
３図〜第１５図に示す。例えば、ＬｉＮｂｏａ　ｕ板上
に′Ｔｉを線状に拡散ざぜ、光挿入用導波路２、光路長
の責なる分岐導波路３．４　ｔ；　Ｊ、び結合用導波路
５を形成し、光路長のｙ４なる分岐導波路３および４の
間でＴ渉訂を形成する。第３図、第４図のものは台形状
に分岐させ、第５図のものは）：１曲状に分岐させてい
るが、何れの場合にも２本の分岐導波路３１３よび４の
長さの差を△Ｌ”Ｌ、３−Ｌ４　　　　　　　　　　（
１＋とし、光の波長をλ、有効屈折率を［）。ｆｆとす
ると、２本の分岐り、９波路の光路差によって生ずる位
相差は、 Δφ−２πｎ　　・△Ｌ／λ　　　　　　（２）ｅｆ’
ｆ となり、温度の変化Δ丁によってこのΔφが変化するの
で、人力喘の光の強度Ｐｉｎに対する出力端の光の強度
は［〕　　　の比ｔよ ｕｔ で表されることになる。従って、光の強電を測定づるこ
とによって温度の変化を検知することがでさる［エル・
Ｊム・ジョンソン（Ｌ、Ｍ、ＪｏｂｒＴ　　Ｓ　　Ｏｎ
　　）　　’８　　、　　Ａ　　ｐ　ｐ　ｆ　　、　　
　Ｐ　　ｈ　　Ｖ　　Ｓ　　、　　　ｌ　　Ｏｔ　　Ｌ
　　／４１３２　弓１３４頁（１９８２）　］　。ここ
でＴと「ｎは挿入１【１失によって決まる［１で、現想
状態ではｒｎ−γ・−１となる。また△φは初期の位相
のずれを表ね−常数であり、ｂは次の式で表わせる値で
ある。[Prior Art] In recent years, optical fiber sensors that combine the characteristics of glass fibers, such as non-induction and high insulation, have been actively developed.The optical system required for fiber sensors is as follows.
Currently, since it is constructed by combining fibers and optical parts such as microlenses, the connection filament between individual parts including the fiber determines the characteristics of the sensor. It has become an essential element. On the other hand, if each part is fabricated using Hakumei-Honba technology or ion diffusion technology and integrated on a single board, it is expected that measurements will be smaller, more stable, and more accurate. Optical waveguide 1%l as above! The sensor is used for optical communication systems or as a measuring device, and as an example, the case where it is used as a temperature sensor is shown in FIGS. 3 to 15. For example, by linearly diffusing Ti on a LiNboa U board, an optical insertion waveguide 2, a branching waveguide 3.4, which is responsible for the optical path length, and a coupling waveguide 5 are formed, and the optical path length is A T crossing is formed between the branch waveguides 3 and 4 called y4. The ones in Figures 3 and 4 are branched into a trapezoidal shape, and the one in Figure 5 is branched into a single curve, but in both cases, the length of the two branching waveguides 313 and 4 is The difference in length is △L"L, 3-L4 (
1+, the wavelength of light is λ, and the effective refractive index is [). ff, the phase difference caused by the optical path difference between the two branches and nine waves is Δφ−2πn ・ΔL/λ (2) ef'
f, and this Δφ changes with the change in temperature Δd, so the intensity of the light at the output end with respect to the intensity Pin of the light from the human input is expressed as the ratio t to ut. Therefore, it is possible to detect changes in temperature by measuring the strong electric current of light.
J.M. Johnson (L, M, JobrT S On
) '8, A p p f,
P h V S , l Ot L
/4132 Bow 134 pages (1982)]. Here, T and ``n are determined by insertion 1 [1 loss [1, and in the current state it becomes rn-γ・-1. Also, △φ represents the initial phase shift - is a constant, and b is It is a value that can be expressed by the following formula.

ここて゛、第１項は屈折率の温１哀係数、第２頂は屈折
率と膨張係数αの積となっている。従って、λ Ｔπ−２ｂＡｌ　　　　　　　　　ｆ５１が位相をπだ
け変化するのに必要な温（資）変化を表わし、これが温
度センサの温度を表わす目安どなる。Here, the first term is the temperature coefficient of the refractive index, and the second term is the product of the refractive index and the expansion coefficient α. Therefore, λ Tπ-2bAl f51 represents the temperature change required to change the phase by π, and this is a measure of the temperature of the temperature sensor.

［発明が解決しようとする問題点］ 上記のように、基板上に同一のイオン拡散にＪ、って分
岐導波路を形成さけた従来の光導波型Ｌンザは、式（５
）かられかるＪ：うに、光路差Δしを長くすることによ
ってＴπを小さくし、感＋ｍをＪ−げる方法が採用され
ていた。そのためには尊波路白体を長くづる必要があり
、本来小型化するという光導波路ヒンサの利点が失われ
るという欠点があった。[Problems to be Solved by the Invention] As mentioned above, the conventional optical waveguide type L sensor that avoids forming a branch waveguide on the substrate for the same ion diffusion is based on the equation (5
) to reduce J: A method has been adopted in which the optical path difference Δ is lengthened to reduce Tπ and increase the sensitivity +m. For this purpose, it is necessary to lengthen the waveguide white body, which has the disadvantage that the original advantage of the optical waveguide hinge, which is miniaturization, is lost.

本発明はかかる欠点をなくし、高感酊でコンバク１へな
光導波型センサを得ることを目的としたものである。It is an object of the present invention to eliminate such drawbacks and to obtain a light waveguide type sensor that is highly sensitive to light.

［問題点を解決するための手段］ 本発明は基板上に形成された、光挿入用導波路とこれに
接続した光路長の異なる２本の分岐導波路と、さらに２
本の導波路を通過した光を結合するための一つの結合用
導波路から構成された光導波路型センサにおいて、光分
岐部における２本の分岐導波路のうち、長い方の分岐導
波路の屈折率あるいは屈折率の温度係数を、短かい方の
分岐導波路の屈折率及び／又は屈折率の温度係数に比べ
て大きくした異種導波路同士で分岐導波路を構成するこ
とによって（４）式に示すしの値を増加させ、同じ長さ
の光導波路を用いてより感度の優れた光導波型センサを
作製しようとするものである。[Means for Solving the Problems] The present invention includes an optical insertion waveguide formed on a substrate, two branch waveguides having different optical path lengths connected to the optical insertion waveguide, and two branch waveguides having different optical path lengths.
In an optical waveguide sensor composed of one coupling waveguide for coupling light that has passed through a main waveguide, refraction of the longer branching waveguide among the two branching waveguides at the optical branching part. By configuring a branch waveguide with different types of waveguides whose index or temperature coefficient of refractive index is larger than the refractive index and/or temperature coefficient of refractive index of the shorter branch waveguide, equation (4) can be obtained. The aim is to increase the value of the optical waveguide and create a more sensitive optical waveguide sensor using an optical waveguide of the same length.

さらに感度を同じにすれば、本発明に基づいて上り小型
の光導波型センサを作製できることは云うまでもない。Furthermore, it goes without saying that if the sensitivities are made the same, a small-sized optical waveguide sensor can be manufactured based on the present invention.

ここで）」根としてガラス又はＬ　ｉＮ　ｂ　Ｏ：ｌを
使用して、イオン交換法により導波路を作成することに
より、より生産を向上させることが可能となる。ざらに
光挿入用導波路と光路長の短かい分岐導波路を屈折率の
低い導波路とし、結合用導波路と光路長の良い分岐導波
路をより高い屈折率の導波路とづることにより、結合部
に於いて開口数の高い（屈折率の高い）導波路から同［
］数の低い（屈折率の低い）導波路に光が入射づること
からくる１失を防止し、両分枝導波路からくる光の強度
のアンバランスをなくすこと／ｙ’＝　ｉＮ能とｈる。Here, by using glass or L iN b O:l as the root and creating a waveguide by an ion exchange method, it is possible to further improve production. By using roughly the optical insertion waveguide and the branching waveguide with a short optical path length as waveguides with a low refractive index, and the coupling waveguide and the branching waveguide with a good optical path length as waveguides with a higher refractive index, At the coupling part, the same [
] To prevent loss caused by light entering a waveguide with a low number (low refractive index), and to eliminate an imbalance in the intensity of light coming from both branch waveguides / y' = iN power and h Ru.

［実施例］ 第１図は本発明の実施例を１、寸ものである。ｉＱ＋。[Example] FIG. 1 shows, in one size, an embodiment of the invention. iQ+.

板１１にイオン交換法によって本発明の光導波路を形成
寸ろ場合、第２図に示すように、まず）Ｊ板１Ｊ、りも
屈折率がわずかに高いイオン（例えば、十 Ｋ　、王＋　　、Ｎａ　　、ｌ＋　　）を拡散ざＵて間
口数の小さい導波路を形成し、これを光路長の短かい分
岐導波路６及び光挿入用導波路２とする。。When forming the optical waveguide of the present invention on the plate 11 by the ion exchange method, as shown in FIG. Na, l+) is diffused to form a waveguide with a small number of openings, and this is used as a branching waveguide 6 with a short optical path length and a waveguide 2 for optical insertion. .

さらに、これよりはるかに高い屈折率を生ずるよ十＋十 うなイオン（例えばＡｇ　、Ｔｌ　　、Ｈ”）を基板１
上に拡散させて開口数の大きな導波路を形成し、これを
光路長の良い分岐導波路７および結合用導波路５とする
（第１図）。分岐導波路６．７の結合部９において、高
間口の導波路から低間口の導波路に入射する時に生ずる
損失を防］Ｆできるため、両分岐導波路６．７からの光
間のアンバランスをなくすことが可能となる。分岐部８
では、光挿入用導波路２からの光ｔよ導波路７の方が導
波路６に比べて開口数が大きいため、容易に導波路７に
分岐可能であり、また結合部９においても同様に導波路
６の光は容易に導波路７に１１１人し１５する。Furthermore, ions (such as Ag, Tl, H'') that produce a much higher refractive index are added to the substrate.
The light is diffused upward to form a waveguide with a large numerical aperture, and this is used as a branching waveguide 7 with a good optical path length and a coupling waveguide 5 (FIG. 1). At the coupling part 9 of the branch waveguide 6.7, it is possible to prevent the loss that occurs when the light enters the waveguide from the high width waveguide to the low width waveguide, thereby reducing the imbalance between the lights from both branch waveguides 6.7. It becomes possible to eliminate Branch 8
Since the numerical aperture of the waveguide 7 is larger than that of the waveguide 6, the light t from the optical insertion waveguide 2 can be easily branched into the waveguide 7, and the same can be said at the coupling part 9. The light in the waveguide 6 easily passes through the waveguide 7.

ここで、本発明の光導波■！セン量ナナ−特性従来の場
合の実施例により比較する。Here, the optical waveguide of the present invention ■! A comparison will be made using an example of the conventional case.

第４図に示すように、基板１として光学ガラス１３に７
を用い、ＫＮＯ＋溶融塩に浸漬してスリットを通してに
４−イオンを拡散させ、導波路３の長さＬ３を１４ｍｍ
、　ＩＪ導波路の長さＬ４を１．３ｍｍ、△１．−　＝
　０．１ｍ＋ｎの導波路を形成した場合、温度センリー
感１ａとし−て′丁π−４２２℃を１！Ｉだ。これに対
し第１図のごとく、■！イオンを拡散さ１！て導波路７
を形成し、Ｋイオンを拡１ｌｌｌ！さけで導波路６を形
成りると、１−π−２０４℃となり、温度センナ−感度
を２１８に増加させることができた。As shown in FIG.
was immersed in KNO + molten salt to diffuse 4- ions through the slit, and the length L3 of the waveguide 3 was set to 14 mm.
, IJ waveguide length L4 is 1.3 mm, △1. −=
When a waveguide of 0.1 m+n is formed, the temperature sensitivity 1a is 1 - 422°C. It's I. On the other hand, as shown in Figure 1, ■! Diffusion of ions 1! Waveguide 7
forms and expands K ions! When the waveguide 6 was formed using salmon, the temperature was 1-π-204°C, and the temperature sensor sensitivity could be increased to 218°C.

同様にＩ３＝　２．８１１１ｍ、　ｌ−４＝　２．０ｍ
ｍどし、Ｉ’３に７を１．↓板としてＫ　イオンのみに
よって１分岐導波路を形成しＩＣ場合、Ｔπ−２１０℃
であるが、導波路６　’、？　Ｋ　　イオン拡散により
、導波路７を△ｑ　イオン拡散によって形成させるとＴ
π＝・１２７℃どく【す、やはり約２倍感度を向」Ｊる
ことがでさた。Similarly, I3=2.8111m, l-4=2.0m
mdoshi, I'3 and 7 to 1. ↓If a one-branch waveguide is formed using only K ions as a plate, Tπ-210℃
But waveguide 6',? When the waveguide 7 is formed by K ion diffusion and △q ion diffusion, T
It was possible to increase the sensitivity by approximately twice as much as π = 127℃.

１、（根をＬｔＮｂＯｌとし、通常のＴｉ拡散によって
導波路を形成させた場合にｔよ、Ｌ：＋　＝　　１４ｍ
ｍ、Ｌ、　＝　　１．３ｍｍの条イ′１ではＴπ＝８４
℃と仕るが、長い導波路７を１１　イオン拡散で作成す
ることに」；ってＴπ−６０℃に感度を増加することが
できた。1. (When the root is LtNbOl and the waveguide is formed by normal Ti diffusion, t, L: + = 14 m
For strip A'1 of m, L, = 1.3 mm, Tπ = 84
By creating a long waveguide 7 by ion diffusion, we were able to increase the sensitivity to Tπ-60°C.

［発明の効果］ 十２の如く、本発明によれば光路差を艮くすることなく
、感度を向上することができるため、］ンバクトな光導
波型上ンサを得ることができる。[Effects of the Invention] As described in item 12, according to the present invention, the sensitivity can be improved without increasing the optical path difference, so that a compact optical waveguide type sensor can be obtained.

【図面の簡単な説明】[Brief explanation of drawings]

第１図は本発明光導波望センサの平面図、第２図は本発
明センサの作製工程を示す平面図、第３図は従来の光導
波型センサの斜視図、第４図は同じく平面図、第５図は
湾曲した分岐導波路をｂつ従来の光導波型センナの平面
図ぐある。 １・・・基板、２・・・光種入用脣波路、５・・・結合
用導波路、６・・・低１ｉＴｌ折率低開口導波路、７・
・・高１１（折Ｘ＄高開口導波路、８・・・分岐部、９
・・・結合部。 出　願　人　　ホーＶ株式会社 代　　理　　人　　　　Ｉ用　　倉　　正　　幸第１図
　　　　　第４図 第３　図 手彰°ごネｒｕｔ正出（自発）Fig. 1 is a plan view of the optical waveguide sensor of the present invention, Fig. 2 is a plan view showing the manufacturing process of the sensor of the invention, Fig. 3 is a perspective view of a conventional optical waveguide sensor, and Fig. 4 is a plan view of the same. , FIG. 5 is a plan view of a conventional optical waveguide sensor having two curved branch waveguides. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Waveguide for optical seed input, 5... Waveguide for coupling, 6... Low 1iTl refractive index low aperture waveguide, 7...
...High 11 (Folded X$ high aperture waveguide, 8... Branch, 9
...Joining part. Applicant: Ho V Co., Ltd. Representative: Masayuki Kura Figure 1 Figure 4 Figure 3 Teakira Gonerut Masade (voluntary)

Claims (1)

【特許請求の範囲】 １　基板上に形成された光挿入用導波路と、これを分岐
した光路長の異なる２本の分岐導波路と、さらに２本の
導波路からの光を結合するための１つの結合用導波路か
ら構成された光導波型センサにおいて、前記２本の分岐
導波路が互いに屈折率及び屈折率の温度係数が異なる導
波路よりなることを特徴とする光導波型センサ。 ２　基板としてガラスを用い、導波路がイオン交換法に
より形成されたことを特徴とする特許請求の範囲第１項
記載の光導波型センサ。 ３　基板としてＬｉＮｂＯ＿３を用いたことを特徴とす
る特許請求の範囲第１項記載の光導波型センサ。 ４　光挿入用導波路と光路長の短かい分岐導波路を屈折
率の低い導波路とし、結合用導波路と光路長の長い分岐
導波路をより高い屈折率の導波路としたことを特徴とす
る特許請求の範囲第１項記載の光導波型センサ。[Claims] 1. An optical insertion waveguide formed on a substrate, two branching waveguides with different optical path lengths branched from this, and a waveguide for coupling light from the two waveguides. An optical waveguide sensor constituted by one coupling waveguide, wherein the two branch waveguides are waveguides having different refractive indexes and different temperature coefficients of refractive index. 2. The optical waveguide sensor according to claim 1, wherein glass is used as the substrate and the waveguide is formed by an ion exchange method. 3. The optical waveguide sensor according to claim 1, characterized in that LiNbO_3 is used as the substrate. 4. The optical insertion waveguide and the branch waveguide with a short optical path length are made into waveguides with a low refractive index, and the coupling waveguide and the branch waveguide with a long optical path length are made into waveguides with a higher refractive index. An optical waveguide type sensor according to claim 1.