JP2011011944A - Faraday rotator - Google Patents
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Abstract
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本発明は、光アイソレータや光サーキュレータなどのファラデー回転子に用いられる希土類鉄ガーネット単結晶に関する。詳しくは、上記光デバイスの小型化に有効な低飽和磁界を有するファラデー回転子に関する。 The present invention relates to a rare earth iron garnet single crystal used for a Faraday rotator such as an optical isolator or an optical circulator. Specifically, the present invention relates to a Faraday rotator having a low saturation magnetic field effective for downsizing the optical device.
光ファイバ通信や光計測では多くの場合、信号源として半導体レーザが使用されている。しかし、半導体レーザは、光ファイバ端面などから反射し、再び半導体レーザ自身に戻ってくるところの所謂反射戻り光があると、発振が不安定になるという重大な欠点がある。そのため半導体レーザの出射側に光アイソレータを設けて、反射戻り光を遮断し、半導体レーザの発振を安定化させることが行われている。
一般的に、光アイソレータは偏光子、検光子、ファラデー回転子およびファラデー回転子を磁気的に飽和させるための永久磁石からなる。そしてファラデー回転子としては、通常一般に、ファラデー効果が大きなビスマス置換希土類鉄ガーネット単結晶（以下、ＲＩＧと適宜略す）厚膜が用いられている。また、ファラデー回転子を磁気的に飽和させるための外部磁界、すなわち飽和磁界が低いと、永久磁石も小型化することができ、光アイソレータの小型化やコスト面において非常に大きなメリットがある。
In many cases of optical fiber communication and optical measurement, a semiconductor laser is used as a signal source. However, the semiconductor laser has a serious drawback that oscillation is unstable if there is so-called reflected return light that is reflected from the end face of the optical fiber and returns to the semiconductor laser itself. Therefore, an optical isolator is provided on the emission side of the semiconductor laser to block the reflected return light and stabilize the oscillation of the semiconductor laser.
In general, an optical isolator includes a polarizer, an analyzer, a Faraday rotator, and a permanent magnet for magnetically saturating the Faraday rotator. As the Faraday rotator, generally, a bismuth-substituted rare earth iron garnet single crystal (hereinafter abbreviated as RIG as appropriate) thick film having a large Faraday effect is used. In addition, when the external magnetic field for magnetically saturating the Faraday rotator, that is, the saturation magnetic field is low, the permanent magnet can also be miniaturized, and there is a great merit in the miniaturization and cost of the optical isolator.
ファラデー回転子の飽和磁界は、ＲＩＧの材料特性、すなわち飽和磁化と、これを研磨、切断など加工したファラデー回転子の形状によって決まる。ファラデー回転子は、１ｍｍ角程度の形状で使われるのが一般的であり、例えば飽和磁化３００（Ｇａｕｓｓ）のＲＩＧを１５５０ｎｍ波長の１ｍｍ角のファラデー回転子に加工すると、飽和磁界は飽和磁化のおおよそ２/３の約２００（Ｏｅ）となる。これは試料形状が変化すると試料内部の反磁界が変化するためである。なお、本出願では、ファラデー回転子の試料形状は代表的な１５５０ｎｍ波長の１ｍｍ角を想定しており、飽和磁界もその形状相当で記載している。
また、さらに飽和磁界は環境温度においても変化するが、本願明細書内の飽和磁界は室温の値として記載している。
これまで、低い飽和磁化を特長とするビスマス置換希土類鉄ガーネット単結晶には、（ＧｄＹＢｉ）３（ＦｅＧａ）５Ｏ１２（特許文献１）、（ＴｂＢｉ）３（ＦｅＧａＡｌ）５Ｏ１２（特許文献２）等が提案され、また、実用化されている。
The saturation magnetic field of the Faraday rotator is determined by the material properties of the RIG, that is, the saturation magnetization and the shape of the Faraday rotator processed by polishing, cutting, or the like. The Faraday rotator is generally used in a shape of about 1 mm square. For example, when a RIG having a saturation magnetization of 300 (Gauss) is processed into a 1 mm square Faraday rotator having a wavelength of 1550 nm, the saturation magnetic field is approximately equal to the saturation magnetization. It becomes about 200 (Oe) of 2/3. This is because the demagnetizing field inside the sample changes when the sample shape changes. In the present application, the sample shape of the Faraday rotator is assumed to be a 1 mm square with a typical wavelength of 1550 nm, and the saturation magnetic field is also described by its shape.
Further, although the saturation magnetic field also changes at the ambient temperature, the saturation magnetic field in this specification is described as a room temperature value.
So far, bismuth-substituted rare earth iron garnet single crystals characterized by low saturation magnetization include (GdYBi) 3 (FeGa) 5 O 12 (Patent Document 1), (TbBi) 3 (FeGaAl) 5 O 12 (Patent Document 2). ) Etc. have been proposed and put into practical use.
ＲＩＧの化学組成は、（ＲＢｉ）３（ＦｅＭ）５Ｏ１２(但し、Ｒは、Ｙや希土類元素を意味し、Ｍは、Ａｌ、Ｇａ、Ｉｎ、Ｓｉ、Ｓｃなどの元素を意味する)で表される。このＲＩＧの飽和磁化は、その構成元素や置換量によって変化する。飽和磁化を低くするためには、希土類元素に特許文献１や特許文献２のように、磁気モーメントが大きく飽和磁化を下げる効果のあるＴｂやＧｄを選び、かつ四面体サイトの鉄を非磁性元素で置換する方法が一般的である。
四面体サイトの鉄を置換するための非磁性元素には、一般にＧａやＡｌが使われる。これは、ＧａやＡｌが、四面体と八面体の２種類ある鉄サイトの内、四面体サイトの方に選択的に置換され、フェリ磁性体であるＲＩＧの飽和磁化を下げる効果があるためである。特にＧａの四面体へのサイト選択率は、一般に９０％程度と言われていて飽和磁化を下げる目的に適している。また、Ａｌの四面体へのサイト選択率は７０％程度と言われていて、Ｇａよりも飽和磁化を下げる効果は小さいが、Ａｌのイオン半径はＧａのそれと比較して小さく、その結果ファラデー回転係数の増加に寄与するＢｉの置換量を大きくすることができるので、ファラデー回転係数を大きく保ち、飽和磁化を下げる目的に適している。ファラデー回転係数が小さいと、ファラデー回転角４５ｄｅｇのファラデー回転子において、必要とする膜厚が大きくなり、結晶育成や研磨等の加工に問題が生じる。本質的にファラデー効果の起因である鉄を非磁性元素で置換するとファラデー効果は悪化することになるため、飽和磁化を調整するためにＧａやＡｌで置換したＲＩＧにおいては一定のファラデー回転係数を持つことも重要となる。
The chemical composition of RIG is (RBi) 3 (FeM) 5 O 12 (where R represents Y or a rare earth element, and M represents an element such as Al, Ga, In, Si, or Sc). expressed. The saturation magnetization of this RIG varies depending on its constituent elements and substitution amount. In order to lower the saturation magnetization, Tb and Gd having a large magnetic moment and an effect of lowering the saturation magnetization are selected as rare earth elements as in Patent Document 1 and Patent Document 2, and iron at the tetrahedral site is used as a nonmagnetic element. The method of replacing with is common.
In general, Ga or Al is used as a nonmagnetic element for substituting iron at a tetrahedral site. This is because Ga and Al are selectively replaced by the tetrahedral site out of the two types of tetrahedral and octahedral iron sites, and have the effect of reducing the saturation magnetization of the ferrimagnetic RIG. is there. In particular, the site selectivity to the tetrahedron of Ga is generally said to be about 90%, which is suitable for the purpose of lowering the saturation magnetization. The site selectivity to the tetrahedron of Al is said to be about 70%, and the effect of lowering the saturation magnetization is smaller than that of Ga, but the ionic radius of Al is smaller than that of Ga, and as a result, Faraday rotation Since the substitution amount of Bi that contributes to the increase in the coefficient can be increased, it is suitable for the purpose of keeping the Faraday rotation coefficient large and lowering the saturation magnetization. When the Faraday rotation coefficient is small, the required film thickness becomes large in the Faraday rotator having a Faraday rotation angle of 45 deg, which causes problems in processing such as crystal growth and polishing. Substituting iron, which is essentially the cause of the Faraday effect, with a nonmagnetic element will worsen the Faraday effect. Therefore, a RIG substituted with Ga or Al to adjust the saturation magnetization has a constant Faraday rotation coefficient. It is also important.
さらに飽和磁化を下げるため、上記のようにＲＩＧの組成を調整する場合、ＲＩＧの磁気補償温度に注意しなければならない。ＲＩＧの磁気補償温度前後では、ファラデー回転角の符号は反転するため、光アイソレータなど光部品としての機能をまったく果たさなくなる。従って、ＲＩＧの磁気補償温度は、これら光部品の使用温度範囲に入らない、例えば−４０℃以下にすることが望ましい。 In order to further reduce the saturation magnetization, when adjusting the RIG composition as described above, attention must be paid to the RIG magnetic compensation temperature. Before and after the magnetic compensation temperature of RIG, the sign of the Faraday rotation angle is reversed, so that it does not function as an optical component such as an optical isolator at all. Accordingly, it is desirable that the RIG magnetic compensation temperature is not within the operating temperature range of these optical components, for example, -40 ° C. or lower.
特許文献１や特許文献２では、希土類元素の種類と鉄を非磁性元素で置換するなどして、飽和磁界を下げている。しかし、特に鉄を非磁性元素で置換すると、ファラデー回転角の温度特性、すなわちファラデー回転角４５ｄｅｇのファラデー回転子において、温度１℃当たりのファラデー回転角の変化が悪化することになる。ＲＩＧの温度特性が悪いと、光アイソレータは外部温度変化にて性能が低下する。
希土類元素の違いでも、例えばＴｂとＧｄを比較した場合、飽和磁界の低下について効果が大きい元素は磁気モーメントの大きいＧｄであるが、Ｔｂを選択すると温度特性は良くなる。
In Patent Document 1 and Patent Document 2, the saturation magnetic field is lowered by replacing the kind of rare earth element and iron with a nonmagnetic element. However, particularly when iron is replaced with a nonmagnetic element, the change in the Faraday rotation angle per 1 ° C. of temperature becomes worse in the temperature characteristic of the Faraday rotation angle, that is, the Faraday rotator having a Faraday rotation angle of 45 deg. When the temperature characteristics of RIG are poor, the performance of the optical isolator is degraded due to external temperature changes.
Even if the difference between the rare earth elements is, for example, when Tb and Gd are compared, the element having a large effect on the reduction of the saturation magnetic field is Gd having a large magnetic moment. However, when Tb is selected, the temperature characteristics are improved.
特許文献１記載の(ＧｄＹＢｉ)３(ＦｅＧａ)５Ｏ１２を使うと、ファラデー回転子の飽和磁界は１３０（Ｏｅ）であるが、温度特性が絶対値で０．１ｄｅｇ/℃と大きくなる（以下、温度特性値は絶対値の値で表記する）。また、特許文献２記載の(ＴｂＢｉ) ３(ＦｅＧａＡｌ)５Ｏ１２を使うと、温度特性は０．０６４ｄｅｇ/℃と小さい値であるが、飽和磁界が３５０（Ｏｅ）とやや大きい。このように、希土類及び非磁性元素の組み合わせで、飽和磁界の調整は従来行われてきた。言い換えると、目標とする飽和磁界を設定すればある程度その組成にて温度特性は決まってしまうのである。
しかし、鉄を置換する非磁性元素の、四面体サイトへのサイト選択率が高まれば、少ない非磁性元素の置換量で飽和磁化を小さくすることができることから、温度特性の悪化を従来よりも抑えることが期待できる。
本発明者らは、特許文献３において、鉄をＧａにて置換することで飽和磁界を下げる場合において、Ａｕるつぼを使うことで、従来のＰｔるつぼを用いた場合に生じるＰｔ＋４イオンのＲＩＧ中への混入を抑えること、及びＣａ２＋をＲＩＧに混入することで、Ｇａの四面体サイトへのサイト選択率が上がり、従来よりも少ないＧａ置換量にて、温度特性を低下させることなく、ＲＩＧの飽和磁界を低下させることが可能であるとの知見を得た。Ｇａ以外の非磁性元素、特にＡｌにおいても同様の効果が得られるか否か検討して、鋭意検討した結果、本発明を完成させた。
When (GdYBi) 3 (FeGa) 5 O 12 described in Patent Document 1 is used, the saturation magnetic field of the Faraday rotator is 130 (Oe), but the temperature characteristic becomes an absolute value as large as 0.1 deg / ° C. The temperature characteristic value is expressed as an absolute value). When (TbBi) 3 (FeGaAl) 5 O 12 described in Patent Document 2 is used, the temperature characteristic is as small as 0.064 deg / ° C., but the saturation magnetic field is slightly large as 350 (Oe). As described above, the saturation magnetic field has been conventionally adjusted with a combination of rare earth elements and nonmagnetic elements. In other words, if the target saturation magnetic field is set, the temperature characteristics are determined to some extent by the composition.
However, if the site selectivity of tetrahedral sites for nonmagnetic elements that replace iron is increased, saturation magnetization can be reduced with a small amount of substitution of nonmagnetic elements, so that deterioration of temperature characteristics is suppressed compared to the conventional case. I can expect that.
In the patent document 3, the present inventors use an Au crucible when lowering a saturation magnetic field by substituting iron with Ga, so that in the RIG of Pt +4 ions generated when a conventional Pt crucible is used. Suppressing the mixing into Ca and adding Ca 2+ into the RIG increases the site selectivity to the tetrahedral site of Ga, and with a smaller Ga substitution amount than before, the RIG does not deteriorate the temperature characteristics. It was found that the saturation magnetic field can be reduced. The present invention was completed as a result of studying whether or not the same effect can be obtained even with nonmagnetic elements other than Ga, particularly Al.
本発明者らは、光アイソレータの小型化につながり、かつ光アイソレータの外部温度変化による性能低下を抑える目的で、飽和磁界が小さく、かつファラデー回転角の温度特性の小さいファラデー回転子を提供することを課題とした。具体的な目標とするファラデー回転子の特性値は、飽和磁界２００（Ｏｅ）以下、ファラデー回転角の温度特性０．０７ｄｅｇ／℃以下、磁気補償温度−４０℃以下、波長１５５０ｎｍでのファラデー回転係数を９００ｄｅｇ／ｃｍ以上と設定した。 The present inventors provide a Faraday rotator with a small saturation magnetic field and a small temperature characteristic of a Faraday rotation angle, for the purpose of reducing the size of the optical isolator and suppressing performance degradation due to external temperature changes of the optical isolator. Was an issue. Specific target Faraday rotator characteristic values are a saturation magnetic field of 200 (Oe) or less, a temperature characteristic of a Faraday rotation angle of 0.07 deg / ° C. or less, a magnetic compensation temperature of −40 ° C. or less, and a Faraday rotation coefficient at a wavelength of 1550 nm. Was set to 900 deg / cm or more.
本発明者らは、上記課題を解決すべく鋭意検討した結果、上記特性値における目標を達成するためには、希土類にＧｄとＴｂを選び、また鉄サイトへの置換元素にＡｌを選んだ上で、ＲＩＧ中のＣａ２＋の混入がＡｌのサイト選択率を上げる効果があることの知見を得て、従来よりも少ないＡｌ置換量にて、温度特性を低下させることなく、ＲＩＧの飽和磁化を下げられることを見出し、本発明を完成させた。
すなわち、化学式ＧｄｘＴｂｙＣａｗＢｉ３-ｘ-ｙ−ｗＦｅ５−ｚＡｌｚＯ１２（式中、０．１５≦ｙ/ｘ≦０．６５，０．３≦ｚ≦０．５，０．０４≦ｗ≦０．１）で示される、液相エピタキシャル法にて育成されるビスマス置換希土類鉄ガーネット単結晶からなるファラデー回転子において、温度特性に優れたことを特徴とする、低飽和磁界型のファラデー回転子を得ることができる。
ファラデー回転子の飽和磁界はできるだけ小さい方が好ましい。上記化学式のＲＩＧにて、サイズ１ｍｍ角相当のファラデー回転子を得る場合、他の物性値、例えば光挿入損失やファラデー回転係数、温度特性などを考慮の上、ＴｂとＧｄの比率を上記化学式の範囲内で選択して、Ａｌ置換量を微調整して一定の飽和磁界以下とすることは、当業者であれば容易であり、このとき本発明を用いることで、最小限のＡｌ置換量にて、例えば、飽和磁界２００（Ｏｅ）以下の飽和磁界が達成されるのである。
As a result of intensive studies to solve the above problems, the present inventors have selected Gd and Tb as rare earths and Al as a substitution element for iron sites in order to achieve the target in the above characteristic values. Thus, the knowledge that mixing of Ca 2+ in the RIG has the effect of increasing the Al site selectivity is obtained, and the saturation magnetization of the RIG is reduced with a lower Al substitution amount than before without degrading the temperature characteristics. As a result, the present invention was completed.
That is, the formula Gd x Tb y Ca w Bi 3 -x-y-w Fe 5-z Al z O 12 ( wherein, 0.15 ≦ y / x ≦ 0.65,0.3 ≦ z ≦ 0.5 , 0.04 ≦ w ≦ 0.1), a Faraday rotator comprising a bismuth-substituted rare earth iron garnet single crystal grown by a liquid phase epitaxial method, characterized by excellent temperature characteristics, A saturated magnetic field type Faraday rotator can be obtained.
The saturation field of the Faraday rotator is preferably as small as possible. In the case of obtaining a Faraday rotator equivalent to a size of 1 mm square by the RIG of the above chemical formula, the ratio of Tb and Gd is set in the above chemical formula in consideration of other physical properties such as optical insertion loss, Faraday rotation coefficient, temperature characteristics, etc. It is easy for those skilled in the art to select within the range and finely adjust the Al substitution amount to be equal to or less than a certain saturation magnetic field. At this time, by using the present invention, the minimum Al substitution amount can be obtained. Thus, for example, a saturation magnetic field of 200 (Oe) or less is achieved.
下表は、実施例１〜４、比較例１〜３の製法で作製したファラデー回転子の評価結果をまとめたものである。
また表内試料はいずれもファラデー回転子の飽和磁界を２００（Ｏｅ）以下に組成を調整して、得られたものとなる。
The table below summarizes the evaluation results of the Faraday rotators produced by the production methods of Examples 1 to 4 and Comparative Examples 1 to 3.
All the samples in the table are obtained by adjusting the composition of the saturation field of the Faraday rotator to 200 (Oe) or less.
表１内、実施例及び比較例記載の（ＴｂＧｄＢｉ）３（ＦｅＡｌ）５Ｏ１２組成を有するＲＩＧにおける、ＧｄとＴｂとの比ｙ／ｘとＡｌの置換量ｚの関係を図１に、またその時のＲＩＧの温度特性の評価結果を図２に示した。
図１と図２では、ＲＩＧ中のＣａ置換量が０．０４以上とそれ以下で分類した。
図１において、Ｔｂの増加（Ｇｄの減少）と共に、飽和磁界を調整するためのＡｌ置換量はより多く必要になってくる。しかし、図１の○（Ｃａ置換量０．０４ｆ．ｕ
未満）と比べ、Ｃａ置換量を増やした●（Ｃａ置換量０．０４ｆ．ｕ以上）の方が、飽和磁界の調整のためのＡｌ置換量を減少させることができ、その結果、図２ように温度特性が改善される。
すなわち本発明によると、（ＴｂＧｄＢｉ）３（ＦｅＡｌ）５Ｏ１２組成を有するＲＩＧ中のＣａ置換量を０．０４以上とし、適宜、ＴｂとＧｄの比率及びＡｌの置換量を調整することで、飽和磁界２００（Ｏｅ）以下、磁気補償温度−４０℃以下、波長１５５０ｎｍでのファラデー回転係数を９００ｄｅｇ／ｃｍ以上を保ちながら、温度特性０．０７ｄｅｇ／℃以下のファラデー回転子が得られる。
また、本発明の実施例はすべて白金るつぼを用いているが、特許文献３と同様に、金るつぼを用いることで、より、飽和磁界を調整するためのＡｌ置換量をさらに減らすことができ、温度特性がより改善される、ということも期待できる。
FIG. 1 shows the relationship between the ratio y / x of Gd and Tb and the amount of substitution z of Al in RIG having the (TbGdBi) 3 (FeAl) 5 O 12 composition described in Table 1, Examples and Comparative Examples. The evaluation results of the temperature characteristics of the RIG at that time are shown in FIG.
In FIG. 1 and FIG. 2, the amount of Ca substitution in RIG is classified into 0.04 or more and less.
In FIG. 1, with the increase in Tb (decrease in Gd), a larger amount of Al substitution is required for adjusting the saturation magnetic field. However, in FIG. 1 ◯ (Ca substitution amount 0.04 f.u
Compared with (less than)), the amount of Ca substitution increased (Ca substitution amount of 0.04 fu. Or more) can reduce the amount of Al substitution for adjusting the saturation magnetic field, and as a result, as shown in FIG. The temperature characteristics are improved.
That is, according to the present invention, the amount of Ca substitution in the RIG having the (TbGdBi) 3 (FeAl) 5 O 12 composition is set to 0.04 or more, and the ratio of Tb and Gd and the amount of substitution of Al are appropriately adjusted. A Faraday rotator having a temperature characteristic of 0.07 deg / ° C. or less can be obtained while maintaining a Faraday rotation coefficient of 900 deg / cm or less at a saturation magnetic field of 200 (Oe) or less, a magnetic compensation temperature of −40 ° C. or less, and a wavelength of 1550 nm.
Moreover, although all the examples of the present invention use a platinum crucible, as in Patent Document 3, by using a gold crucible, it is possible to further reduce the amount of Al substitution for adjusting the saturation magnetic field, It can also be expected that the temperature characteristics are further improved.
Ｇｄの置換量ｘとＴｂの置換量ｙの比率(ｙ/ｘ)は、０．１５以上０．６５以下が好ましい。ｙ/ｘが、０．１５未満ではＢｉ置換量が減り、必要な膜厚が厚くなるので好ましくない。また、ｙ/ｘが、０．６５を超えると逆にＢｉの置換量が増え、結晶内部でのひずみ等が原因で、育成中の割れ及びクラック等により必要な膜厚を得るための育成が困難となる。加えてＴｂの置換量が増えると、１６５０ｎｍ域での挿入損失が増えるなど、好ましくない。Ａｌの置換量ｚは、少ないことが好ましい。本発明を用いるとＡｌの置換量は、０．３〜０．５の範囲に抑えられる。また、Ｃａの置換量ｗは０．１を超えると挿入損失が上昇し、光学素子として相応しくない。
The ratio (y / x) between the substitution amount x of Gd and the substitution amount y of Tb is preferably 0.15 or more and 0.65 or less. If y / x is less than 0.15, the amount of Bi substitution decreases and the required film thickness increases, which is not preferable. On the other hand, if y / x exceeds 0.65, the amount of substitution of Bi increases, and the growth to obtain the required film thickness due to cracks and cracks during the growth due to the strain inside the crystal and the like. It becomes difficult. In addition, an increase in the amount of substitution of Tb is not preferable, such as an increase in insertion loss in the 1650 nm region. The substitution amount z of Al is preferably small. When the present invention is used, the substitution amount of Al is suppressed to a range of 0.3 to 0.5. Further, when the Ca substitution amount w exceeds 0.1, the insertion loss increases, which is not suitable as an optical element.
本発明に用いる上記ＲＩＧ膜の製造に用いる種結晶基板としては、公知のものが使用できる。一般には、格子定数が１．２４９０ｎｍから１．２５１５ｎｍの非磁性ガーネット［（ＧｄＣａ）３（ＧａＭｇＺｒ）５Ｏ１２］基板から適宜選択する。
以下、表１に記載したＲＩＧの製法と評価結果の詳細を記載する。なお、実施例及び比較例に用いている試薬はすべて３Ｎかそれ以上の高純度試薬を用いている。
A known substrate can be used as the seed crystal substrate used for manufacturing the RIG film used in the present invention. In general, it is appropriately selected from a nonmagnetic garnet [(GdCa) 3 (GaMgZr) 5 O 12 ] substrate having a lattice constant of 1.2490 nm to 1.2515 nm.
The details of the RIG production methods and evaluation results described in Table 1 are described below. All reagents used in Examples and Comparative Examples are high purity reagents of 3N or more.
実施例１
白金るつぼに酸化ビスマス[Ｂｉ２Ｏ３]４７００ｇ、酸化第２鉄[Ｆｅ２Ｏ３]３１０ｇ、酸化ほう素[Ｂ２Ｏ３]８５ｇ、酸化鉛[ＰｂＯ]９００ｇ、酸化テルビウム[Ｔｂ４Ｏ７]２０ｇ、酸化ガドリニウム[Ｇｄ２Ｏ３]４５ｇ、酸化アルミニウム[Ａｌ２Ｏ３]１５ｇ、酸化カルシウム [ＣａＯ]３ｇを仕込み融液とした。
この融液を精密縦型管状電気炉の所定の位置に設置し、１０００℃に加熱溶融し、十分に攪拌することで均一に混合してＲＩＧ育成融液とした。ここに得られた融液の温度を飽和温度以下の温度まで低下させて後、融液表面に、厚さが７６０μｍで、格子定数が１．２.４９７±０．０００２ｎｍの３インチ（１１１）ガーネット単結晶[(ＧｄＣａ)３(ＧａＭｇＺｒ)５Ｏ１２]基板の片面を接触させ、基板を回転させながらエピタキシャル成長を行った結果、膜厚５２０μｍのＲＩＧ（以下ＲＩＧ-１と記す）を得た。この結晶をＥＰＭＡ定量分析により組成分析した結果、組成はＧｄ１．６３Ｔｂ０．３３Ｃａ０．０４Ｂｉ１．００Ｆｅ４．６６Ａｌ０．３４Ｏ１２であった。得られたＲＩＧ−１を１１ｍｍ×１１ｍｍに分割した後、基板を除去し、波長１５５０ｎｍでのファラデー回転角が４５度になるように厚さを調整した。厚さは４７６μｍであった。すなわち、ファラデー回転係数は９４５ｄｅｇ／ｃｍであった。その後、波長１５５０ｎｍを中心とする反射防止膜を付与した。
次に、任意の１１ｍｍ×１１ｍｍのＲＩＧ-１を１枚選択し、磁気補償温度を測定した結果、−４０℃以下であったことを確認した。その後、このＲＩＧ-１を１ｍｍ×１ｍｍに切断後、そのうちの１チップを選択し、飽和磁界を測定した結果、値は１４０（Ｏｅ）であった。また、ファラデー回転角の温度特性を測定した結果、値は０．０６９（ｄｅｇ／℃）であった。
Example 1
In a platinum crucible, 4700 g of bismuth oxide [Bi 2 O 3 ], 310 g of ferric oxide [Fe 2 O 3 ], 85 g of boron oxide [B 2 O 3 ], 900 g of lead oxide [PbO], terbium oxide [Tb 4 O 7 20 g, 45 g of gadolinium oxide [Gd 2 O 3 ], 15 g of aluminum oxide [Al 2 O 3 ] and 3 g of calcium oxide [CaO] were used as a melt.
This melt was placed at a predetermined position of a precision vertical tubular electric furnace, heated and melted to 1000 ° C., and sufficiently mixed with sufficient stirring to obtain a RIG growth melt. After the temperature of the melt thus obtained is lowered to a temperature below the saturation temperature, 3 inches (111) having a thickness of 760 μm and a lattice constant of 1.2.497 ± 0.0002 nm are formed on the surface of the melt. One side of a garnet single crystal [(GdCa) 3 (GaMgZr) 5 O 12 ] substrate was brought into contact and epitaxial growth was performed while rotating the substrate. As a result, an RIG having a thickness of 520 μm (hereinafter referred to as RIG-1) was obtained. As a result of analyzing the composition of the crystal by EPMA quantitative analysis, the composition was Gd 1.63 Tb 0.33 Ca 0.04 Bi 1.00 Fe 4.66 Al 0.34 O 12 . After dividing the obtained RIG-1 into 11 mm × 11 mm, the substrate was removed, and the thickness was adjusted so that the Faraday rotation angle at a wavelength of 1550 nm was 45 degrees. The thickness was 476 μm. That is, the Faraday rotation coefficient was 945 deg / cm. Thereafter, an antireflection film centered on a wavelength of 1550 nm was applied.
Next, an arbitrary 11 mm × 11 mm RIG-1 was selected and the magnetic compensation temperature was measured. As a result, it was confirmed that the temperature was −40 ° C. or lower. Then, after cutting this RIG-1 into 1 mm × 1 mm, one chip was selected and the saturation magnetic field was measured. As a result, the value was 140 (Oe). Moreover, as a result of measuring the temperature characteristics of the Faraday rotation angle, the value was 0.069 (deg / ° C.).
実施例２
白金るつぼに酸化ビスマス[Ｂｉ２Ｏ３]４６５０ｇ、酸化第２鉄[Ｆｅ２Ｏ３]３７０ｇ、酸化ほう素[Ｂ２Ｏ３]３５ｇ、酸化鉛[ＰｂＯ]９００ｇ、酸化テルビウム[Ｔｂ４Ｏ７]１３ｇ、酸化ガドリニウム[Ｇｄ２Ｏ３]３０ｇ、酸化アルミニウム[Ａｌ２Ｏ３]１４ｇ、酸化カルシウム[ＣａＯ]３ｇを仕込み融液とした。
この融液を精密縦型管状電気炉の所定の位置に設置し、１０００℃に加熱溶融し、十分に攪拌することで均一に混合してＲＩＧ育成融液とした。ここに得られた融液を用い、実施例１と同様にエピタキシャル成長を行った結果、膜厚５５０μｍのＲＩＧ（以下ＲＩＧ-２と記す）を得た。この結晶をＥＰＭＡ定量分析により組成分析した結果、組成はＧｄ１．２９Ｔｂ０．５４Ｃａ０．０５Ｂｉ１．１２Ｆｅ４．５２Ａｌ０．４８Ｏ１２であった。得られたＲＩＧ−２を１１ｍｍ×１１ｍｍに分割した後、基板を除去し、波長１５５０ｎｍでのファラデー回転角が４５度になるように厚さを調整した。厚さは４３７μｍであった。すなわち、ファラデー回転係数は１０３０ｄｅｇ／ｃｍであった。その後、波長１５５０ｎｍを中心とする反射防止膜を付与した。
次に、任意の１１ｍｍ×１１ｍｍのＲＩＧ-２を１枚選択し、磁気補償温度を測定した結果、−４０℃以下であったことを確認した。その後、このＲＩＧ-２を１ｍｍ×１ｍｍに切断後、そのうちの1チップを選択し、飽和磁界を測定した結果、値は１６０（Ｏｅ）であった。また、ファラデー回転角の温度特性を測定した結果、値は０．０６９（ｄｅｇ／℃）であった。
Example 2
In a platinum crucible, 4650 g of bismuth oxide [Bi 2 O 3 ], 370 g of ferric oxide [Fe 2 O 3 ], 35 g of boron oxide [B 2 O 3 ], 900 g of lead oxide [PbO], terbium oxide [Tb 4 O 7 13 g, 30 g of gadolinium oxide [Gd 2 O 3 ], 14 g of aluminum oxide [Al 2 O 3 ] and 3 g of calcium oxide [CaO] were used as a melt.
This melt was placed at a predetermined position of a precision vertical tubular electric furnace, heated and melted to 1000 ° C., and sufficiently mixed with sufficient stirring to obtain a RIG growth melt. Using the melt obtained here, epitaxial growth was performed in the same manner as in Example 1. As a result, RIG (hereinafter referred to as RIG-2) having a film thickness of 550 μm was obtained. As a result of analyzing the composition of this crystal by EPMA quantitative analysis, the composition was Gd 1.29 Tb 0.54 Ca 0.05 Bi 1.12 Fe 4.52 Al 0.48 O 12 . After dividing the obtained RIG-2 into 11 mm × 11 mm, the substrate was removed, and the thickness was adjusted so that the Faraday rotation angle at a wavelength of 1550 nm was 45 degrees. The thickness was 437 μm. That is, the Faraday rotation coefficient was 1030 deg / cm. Thereafter, an antireflection film centered on a wavelength of 1550 nm was applied.
Next, one arbitrary RIG-2 of 11 mm × 11 mm was selected and the magnetic compensation temperature was measured. As a result, it was confirmed that the temperature was −40 ° C. or lower. Then, after cutting this RIG-2 into 1 mm × 1 mm, one chip was selected and the saturation magnetic field was measured. As a result, the value was 160 (Oe). Moreover, as a result of measuring the temperature characteristics of the Faraday rotation angle, the value was 0.069 (deg / ° C.).
実施例３
白金るつぼに酸化ビスマス[Ｂｉ２Ｏ３]４７００ｇ、酸化第２鉄[Ｆｅ２Ｏ３]３８０ｇ、酸化ほう素[Ｂ２Ｏ３]３０ｇ、酸化鉛[ＰｂＯ]８５０ｇ、酸化テルビウム[Ｔｂ４Ｏ７]１５ｇ、酸化ガドリニウム[Ｇｄ２Ｏ３]３５ｇ、酸化アルミニウム[Ａｌ２Ｏ３]１２ｇ、酸化カルシウム[ＣａＯ]３ｇを仕込み融液とした。
この融液を精密縦型管状電気炉の所定の位置に設置し、１０００℃に加熱溶融し、十分に攪拌することで均一に混合してＲＩＧ育成融液とした。ここに得られた融液を用い、実施例１と同様にエピタキシャル成長を行った結果、膜厚５３０μｍのＲＩＧ（以下ＲＩＧ-３と記す）を得た。この結晶をＥＰＭＡ定量分析により組成分析した結果、組成はＧｄ１．２７Ｔｂ０．５９Ｃａ０．０５Ｂｉ１．０９Ｆｅ４．５６Ａｌ０．４４Ｏ１２であった。得られたＲＩＧ−３を１１ｍｍ×１１ｍｍに分割した後、基板を除去し、波長１５５０ｎｍでのファラデー回転角が４５度になるように厚さを調整した。厚さは４７０μｍであった。すなわち、ファラデー回転係数は９５７ｄｅｇ／ｃｍであった。その後、波長１５５０ｎｍを中心とする反射防止膜を付与した。
次に、任意の１１ｍｍ×１１ｍｍのＲＩＧ-３を１枚選択し、磁気補償温度を測定した結果、−４０℃以下であったことを確認した。その後、このＲＩＧ-３を１ｍｍ×１ｍｍに切断後、そのうちの１チップを選択し、飽和磁界を測定した結果、値は１４３（Ｏｅ）であった。また、ファラデー回転角の温度特性を測定した結果、値は０．０６９（ｄｅｇ／℃）であった。
Example 3
In a platinum crucible, 4700 g of bismuth oxide [Bi 2 O 3 ], 380 g of ferric oxide [Fe 2 O 3 ], 30 g of boron oxide [B 2 O 3 ], 850 g of lead oxide [PbO], terbium oxide [Tb 4 O 7 15 g, 35 g of gadolinium oxide [Gd 2 O 3 ], 12 g of aluminum oxide [Al 2 O 3 ] and 3 g of calcium oxide [CaO] were used as a melt.
This melt was placed at a predetermined position of a precision vertical tubular electric furnace, heated and melted to 1000 ° C., and sufficiently mixed with sufficient stirring to obtain a RIG growth melt. Using the melt obtained here, epitaxial growth was performed in the same manner as in Example 1. As a result, RIG (hereinafter referred to as RIG-3) having a film thickness of 530 μm was obtained. As a result of analyzing the composition of this crystal by EPMA quantitative analysis, the composition was Gd 1.27 Tb 0.59 Ca 0.05 Bi 1.09 Fe 4.56 Al 0.44 O 12 . After the obtained RIG-3 was divided into 11 mm × 11 mm, the substrate was removed, and the thickness was adjusted so that the Faraday rotation angle at a wavelength of 1550 nm was 45 degrees. The thickness was 470 μm. That is, the Faraday rotation coefficient was 957 deg / cm. Thereafter, an antireflection film centered on a wavelength of 1550 nm was applied.
Next, one arbitrary RIG-3 of 11 mm × 11 mm was selected and the magnetic compensation temperature was measured. As a result, it was confirmed that the temperature was −40 ° C. or lower. Then, after cutting this RIG-3 into 1 mm × 1 mm, one chip was selected and the saturation magnetic field was measured. As a result, the value was 143 (Oe). Moreover, as a result of measuring the temperature characteristics of the Faraday rotation angle, the value was 0.069 (deg / ° C.).
実施例４
白金るつぼに酸化ビスマス[Ｂｉ２Ｏ３]４５００ｇ、酸化第２鉄[Ｆｅ２Ｏ３]３５０ｇ、酸化ほう素[Ｂ２Ｏ３]５０ｇ、酸化鉛[ＰｂＯ]９００ｇ、酸化テルビウム[Ｔｂ４Ｏ７]１５ｇ、酸化ガドリニウム[Ｇｄ２Ｏ３]３０ｇ、酸化アルミニウム[Ａｌ２Ｏ３]１５ｇ、酸化カルシウム[ＣａＯ]３ｇを仕込み融液とした。
この融液を精密縦型管状電気炉の所定の位置に設置し、１０００℃に加熱溶融し、十分に攪拌することで均一に混合してＲＩＧ育成融液とした。ここに得られた融液を用い、実施例１と同様にエピタキシャル成長を行った結果、膜厚５６０μｍのＲＩＧ（以下ＲＩＧ-４と記す）を得た。この結晶をＥＰＭＡ定量分析により組成分析した結果、組成はＧｄ１．３０Ｔｂ０．５８Ｃａ０．０５Ｂｉ１．０７Ｆｅ４．５８Ａｌ０．４２Ｏ１２であった。得られたＲＩＧ−４を１１ｍｍ×１１ｍｍに分割した後、基板を除去し、波長１５５０ｎｍでのファラデー回転角が４５度になるように厚さを調整した。厚さは４５４μｍであった。すなわち、ファラデー回転係数は９９２ｄｅｇ／ｃｍであった。その後、波長１５５０ｎｍを中心とする反射防止膜を付与した。
次に、任意の１１ｍｍ×１１ｍｍのＲＩＧ-４を１枚選択し、磁気補償温度を測定した結果、−４０℃以下であったことを確認した。その後、このＲＩＧ-４を１ｍｍ×１ｍｍに切断後、そのうちの1チップを選択し、飽和磁界を測定した結果、値は１４７（Ｏｅ）であった。また、ファラデー回転角の温度特性を測定した結果、値は０．０６８（ｄｅｇ／℃）であった。
Example 4
In a platinum crucible, 4500 g of bismuth oxide [Bi 2 O 3 ], 350 g of ferric oxide [Fe 2 O 3 ], 50 g of boron oxide [B 2 O 3 ], 900 g of lead oxide [PbO], terbium oxide [Tb 4 O 7 15 g, 30 g of gadolinium oxide [Gd 2 O 3 ], 15 g of aluminum oxide [Al 2 O 3 ] and 3 g of calcium oxide [CaO] were used as a melt.
This melt was placed at a predetermined position of a precision vertical tubular electric furnace, heated and melted to 1000 ° C., and sufficiently mixed with sufficient stirring to obtain a RIG growth melt. Using the melt obtained here, epitaxial growth was performed in the same manner as in Example 1. As a result, RIG (hereinafter referred to as RIG-4) having a film thickness of 560 μm was obtained. As a result of analyzing the composition of the crystals by EPMA quantitative analysis, the composition was Gd 1.30 Tb 0.58 Ca 0.05 Bi 1.07 Fe 4.58 Al 0.42 O 12 . After dividing the obtained RIG-4 into 11 mm × 11 mm, the substrate was removed, and the thickness was adjusted so that the Faraday rotation angle at a wavelength of 1550 nm was 45 degrees. The thickness was 454 μm. That is, the Faraday rotation coefficient was 992 deg / cm. Thereafter, an antireflection film centered on a wavelength of 1550 nm was applied.
Next, one arbitrary RIG-4 of 11 mm × 11 mm was selected and the magnetic compensation temperature was measured. As a result, it was confirmed that the temperature was −40 ° C. or lower. Then, after cutting this RIG-4 into 1 mm × 1 mm, one chip was selected and the saturation magnetic field was measured. As a result, the value was 147 (Oe). Moreover, as a result of measuring the temperature characteristics of the Faraday rotation angle, the value was 0.068 (deg / ° C.).
比較例１
白金るつぼに酸化ビスマス[Ｂｉ２Ｏ３]５１００ｇ、酸化第２鉄[Ｆｅ２Ｏ３]２９０ｇ、酸化ほう素[Ｂ２Ｏ３]５０ｇ、酸化鉛[ＰｂＯ]５００ｇ、酸化テルビウム[Ｔｂ４Ｏ７]２０ｇ、酸化ガドリニウム[Ｇｄ２Ｏ３]４５ｇ、酸化アルミニウム[Ａｌ２Ｏ３]１３ｇ、酸化カルシウム[ＣａＯ]１ｇを仕込み融液とした。
この融液を精密縦型管状電気炉の所定の位置に設置し、１０００℃に加熱溶融し、十分に攪拌することで均一に混合してＲＩＧ育成融液とした。ここに得られた融液を用い、実施例１と同様にエピタキシャル成長を行った結果、膜厚５３０μｍのＲＩＧ（以下ＲＩＧ-５と記す）を得た。この結晶をＥＰＭＡ定量分析により組成分析した結果、組成はＧｄ１．６９Ｔｂ０．２６Ｃａ０．０２Ｂｉ１．０３Ｆｅ４．５２Ａｌ０．４８Ｏ１２であった。得られたＲＩＧ−５を１１ｍｍ×１１ｍｍに分割した後、基板を除去し、波長１５５０ｎｍでのファラデー回転角が４５度になるように厚さを調整した。厚さは４７８μｍであった。すなわち、ファラデー回転係数は９４２ｄｅｇ／ｃｍであった。その後、波長１５５０ｎｍを中心とする反射防止膜を付与した。
次に、任意の１１ｍｍ×１１ｍｍのＲＩＧ-５を１枚選択し、磁気補償温度を測定した結果、−４０℃以下であったことを確認した。その後、このＲＩＧ-５を１ｍｍ×１ｍｍに切断後、そのうちの1チップを選択し、飽和磁界を測定した結果、値は１５４（Ｏｅ）であった。また、ファラデー回転角の温度特性を測定した結果、値は０．０７３（ｄｅｇ／℃）であった。
Comparative Example 1
In a platinum crucible, 5100 g of bismuth oxide [Bi 2 O 3 ], 290 g of ferric oxide [Fe 2 O 3 ], 50 g of boron oxide [B 2 O 3 ], 500 g of lead oxide [PbO], terbium oxide [Tb 4 O 7 20 g, 45 g of gadolinium oxide [Gd 2 O 3 ], 13 g of aluminum oxide [Al 2 O 3 ], and 1 g of calcium oxide [CaO] were used as a melt.
This melt was placed at a predetermined position of a precision vertical tubular electric furnace, heated and melted to 1000 ° C., and sufficiently mixed with sufficient stirring to obtain a RIG growth melt. Using the melt obtained here, epitaxial growth was performed in the same manner as in Example 1. As a result, RIG (hereinafter referred to as RIG-5) having a film thickness of 530 μm was obtained. As a result of analyzing the composition of this crystal by EPMA quantitative analysis, the composition was Gd 1.69 Tb 0.26 Ca 0.02 Bi 1.03 Fe 4.52 Al 0.48 O 12 . After dividing the obtained RIG-5 into 11 mm × 11 mm, the substrate was removed, and the thickness was adjusted so that the Faraday rotation angle at a wavelength of 1550 nm was 45 degrees. The thickness was 478 μm. That is, the Faraday rotation coefficient was 942 deg / cm. Thereafter, an antireflection film centered on a wavelength of 1550 nm was applied.
Next, an arbitrary 11 mm × 11 mm RIG-5 was selected and the magnetic compensation temperature was measured. As a result, it was confirmed that the temperature was −40 ° C. or lower. Then, after cutting this RIG-5 into 1 mm × 1 mm, one chip was selected and the saturation magnetic field was measured. As a result, the value was 154 (Oe). Moreover, as a result of measuring the temperature characteristic of the Faraday rotation angle, the value was 0.073 (deg / ° C.).
比較例２
白金るつぼに酸化ビスマス[Ｂｉ２Ｏ３]５２００ｇ、酸化第２鉄[Ｆｅ２Ｏ３]２８０ｇ、酸化ほう素[Ｂ２Ｏ３]４０ｇ、酸化鉛[ＰｂＯ]４５０ｇ、酸化テルビウム[Ｔｂ４Ｏ７]２０ｇ、酸化ガドリニウム[Ｇｄ２Ｏ３]４０ｇ、酸化アルミニウム[Ａｌ２Ｏ３]１３ｇ、酸化カルシウム[ＣａＯ]１ｇを仕込み融液とした。
この融液を精密縦型管状電気炉の所定の位置に設置し、１０００℃に加熱溶融し、十分に攪拌することで均一に混合してＲＩＧ育成融液とした。ここに得られた融液を用い、実施例１と同様にエピタキシャル成長を行った結果、膜厚５４０μｍのＲＩＧ（以下ＲＩＧ-６と記す）を得た。この結晶をＥＰＭＡ定量分析により組成分析した結果、組成はＧｄ１．２８Ｔｂ０．６４Ｃａ０．０１Ｂｉ１．０７Ｆｅ４．３８Ａｌ０．６２Ｏ１２であった。得られたＲＩＧ−６を１１ｍｍ×１１ｍｍに分割した後、基板を除去し、波長１５５０ｎｍでのファラデー回転角が４５度になるように厚さを調整した。厚さは４７４μｍであった。すなわち、ファラデー回転係数は９５０ｄｅｇ／ｃｍであった。その後、波長１５５０ｎｍを中心とする反射防止膜を付与した。
次に、任意の１１ｍｍ×１１ｍｍのＲＩＧ-６を１枚選択し、磁気補償温度を測定した結果、−４０℃以下であったことを確認した。その後、このＲＩＧ-６を１ｍｍ×１ｍｍに切断後、そのうちの1チップを選択し、飽和磁界を測定した結果、値は１５２（Ｏｅ）であった。また、ファラデー回転角の温度特性を測定した結果、値は０．０７４（ｄｅｇ／℃）であった。
Comparative Example 2
In a platinum crucible, 5200 g of bismuth oxide [Bi 2 O 3 ], 280 g of ferric oxide [Fe 2 O 3 ], 40 g of boron oxide [B 2 O 3 ], 450 g of lead oxide [PbO], terbium oxide [Tb 4 O 7 20 g, 40 g of gadolinium oxide [Gd 2 O 3 ], 13 g of aluminum oxide [Al 2 O 3 ], and 1 g of calcium oxide [CaO] were used as a melt.
This melt was placed at a predetermined position of a precision vertical tubular electric furnace, heated and melted to 1000 ° C., and sufficiently mixed with sufficient stirring to obtain a RIG growth melt. Using the melt obtained here, epitaxial growth was performed in the same manner as in Example 1. As a result, RIG (hereinafter referred to as RIG-6) having a film thickness of 540 μm was obtained. The composition of this crystal was analyzed by EPMA quantitative analysis. As a result, the composition was Gd 1.28 Tb 0.64 Ca 0.01 Bi 1.07 Fe 4.38 Al 0.62 O 12 . After dividing the obtained RIG-6 into 11 mm × 11 mm, the substrate was removed, and the thickness was adjusted so that the Faraday rotation angle at a wavelength of 1550 nm was 45 degrees. The thickness was 474 μm. That is, the Faraday rotation coefficient was 950 deg / cm. Thereafter, an antireflection film centered on a wavelength of 1550 nm was applied.
Next, an arbitrary 11 mm × 11 mm RIG-6 was selected and the magnetic compensation temperature was measured. As a result, it was confirmed that the temperature was −40 ° C. or lower. Then, after cutting this RIG-6 into 1 mm × 1 mm, one chip was selected and the saturation magnetic field was measured. As a result, the value was 152 (Oe). Moreover, as a result of measuring the temperature characteristics of the Faraday rotation angle, the value was 0.074 (deg / ° C.).
比較例３
白金るつぼに酸化ビスマス[Ｂｉ２Ｏ３]４５００ｇ、酸化第２鉄[Ｆｅ２Ｏ３]３５０ｇ、酸化ほう素[Ｂ２Ｏ３]３５ｇ、酸化鉛[ＰｂＯ]８９０ｇ、酸化テルビウム[Ｔｂ４Ｏ７]１５ｇ、酸化ガドリニウム[Ｇｄ２Ｏ３]２５ｇ、酸化アルミニウム[Ａｌ２Ｏ３]１５ｇ、酸化カルシウム[ＣａＯ]３ｇを仕込み融液とした。
この融液を精密縦型管状電気炉の所定の位置に設置し、１０００℃に加熱溶融し、十分に攪拌することで均一に混合してＲＩＧ育成融液とした。ここに得られた融液を用い、実施例１と同様にエピタキシャル成長を行った結果、膜厚４８０μｍのＲＩＧ（以下ＲＩＧ-７と記す）を得た。この結晶をＥＰＭＡ定量分析により組成分析した結果、組成はＧｄ１．０８Ｔｂ０．７１Ｃａ０．０５Ｂｉ１．１６Ｆｅ４．４６Ａｌ０．５４Ｏ１２であった。得られたＲＩＧ−７を１１ｍｍ×１１ｍｍに分割した後、基板を除去し、波長１５５０ｎｍでのファラデー回転角が４５度になるように厚さを調整した。厚さは４０３μｍであった。すなわち、ファラデー回転係数は１１１６ｄｅｇ／ｃｍであった。その後、波長１５５０ｎｍを中心とする反射防止膜を付与した。
次に、任意の１１ｍｍ×１１ｍｍのＲＩＧ-７を１枚選択し、磁気補償温度を測定した結果、−４０℃以下であったことを確認した。その後、このＲＩＧ-７を１ｍｍ×１ｍｍに切断後、そのうちの１チップを選択し、飽和磁界を測定した結果、値は１７２（Ｏｅ）であった。また、ファラデー回転角の温度特性を測定した結果、値は０．０６７（ｄｅｇ／℃）であった。次いで波長１６５０ｎｍ挿入損失を測定した結果、０．２３ｄＢであった。このような大きな損失はファラデー回転子の特性として相応しくないものである。
Comparative Example 3
In a platinum crucible, 4500 g of bismuth oxide [Bi 2 O 3 ], 350 g of ferric oxide [Fe 2 O 3 ], 35 g of boron oxide [B 2 O 3 ], 890 g of lead oxide [PbO], terbium oxide [Tb 4 O 7 15 g, 25 g of gadolinium oxide [Gd 2 O 3 ], 15 g of aluminum oxide [Al 2 O 3 ] and 3 g of calcium oxide [CaO] were used as a melt.
This melt was placed at a predetermined position of a precision vertical tubular electric furnace, heated and melted to 1000 ° C., and sufficiently mixed with sufficient stirring to obtain a RIG growth melt. Using the melt obtained here, epitaxial growth was performed in the same manner as in Example 1. As a result, RIG (hereinafter referred to as RIG-7) having a film thickness of 480 μm was obtained. As a result of analyzing the composition of this crystal by EPMA quantitative analysis, the composition was Gd 1.08 Tb 0.71 Ca 0.05 Bi 1.16 Fe 4.46 Al 0.54 O 12 . After dividing the obtained RIG-7 into 11 mm × 11 mm, the substrate was removed, and the thickness was adjusted so that the Faraday rotation angle at a wavelength of 1550 nm was 45 degrees. The thickness was 403 μm. That is, the Faraday rotation coefficient was 1116 deg / cm. Thereafter, an antireflection film centered on a wavelength of 1550 nm was applied.
Next, an arbitrary 11 mm × 11 mm RIG-7 was selected and the magnetic compensation temperature was measured. As a result, it was confirmed that the temperature was −40 ° C. or lower. Then, after cutting this RIG-7 into 1 mm × 1 mm, one chip was selected and the saturation magnetic field was measured. As a result, the value was 172 (Oe). Moreover, as a result of measuring the temperature characteristics of the Faraday rotation angle, the value was 0.067 (deg / ° C.). Next, the insertion loss at a wavelength of 1650 nm was measured and found to be 0.23 dB. Such a large loss is not suitable as a characteristic of a Faraday rotator.
本発明によれば、飽和磁界が低く、また温度特性に優れたファラデー回転子を得ることができ、その産業上の意義は極めて高い。
According to the present invention, a Faraday rotator having a low saturation magnetic field and excellent temperature characteristics can be obtained, and its industrial significance is extremely high.
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5377785B1 (en) * | 2013-03-28 | 2013-12-25 | 株式会社グラノプト | Bismuth-substituted rare earth iron garnet single crystal and method for producing the same |
| JP2018028499A (en) * | 2016-08-19 | 2018-02-22 | シチズンファインデバイス株式会社 | Magnetic field sensor element and magnetic field sensor device |
| GB2600860A (en) * | 2015-06-15 | 2022-05-11 | Skyworks Solutions Inc | Ultra-high dielectric constant garnet |
-
2009
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP5377785B1 (en) * | 2013-03-28 | 2013-12-25 | 株式会社グラノプト | Bismuth-substituted rare earth iron garnet single crystal and method for producing the same |
| GB2600860A (en) * | 2015-06-15 | 2022-05-11 | Skyworks Solutions Inc | Ultra-high dielectric constant garnet |
| GB2600860B (en) * | 2015-06-15 | 2022-08-17 | Skyworks Solutions Inc | Ultra-high dielectric constant garnet |
| US11987531B2 (en) | 2015-06-15 | 2024-05-21 | Skyworks Solutions, Inc. | Ultra-high dielectric constant garnet |
| JP2018028499A (en) * | 2016-08-19 | 2018-02-22 | シチズンファインデバイス株式会社 | Magnetic field sensor element and magnetic field sensor device |
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