JP4807288B2

JP4807288B2 - Magnetic garnet single crystal, optical element using the same, and method for producing magnetic garnet single crystal

Info

Publication number: JP4807288B2
Application number: JP2007071191A
Authority: JP
Inventors: 敦大井戸
Original assignee: TDK Corp
Current assignee: TDK Corp
Priority date: 2004-11-19
Filing date: 2007-03-19
Publication date: 2011-11-02
Anticipated expiration: 2025-09-30
Also published as: JP2007217278A

Description

本発明は、液相エピタキシャル（ＬＰＥ）法により育成した磁性ガーネット単結晶及びそれを用いた光学素子並びに磁性ガーネット単結晶の製造方法に関する。 The present invention relates to a magnetic garnet single crystal grown by a liquid phase epitaxial (LPE) method, an optical element using the same, and a method for producing a magnetic garnet single crystal.

通信用光アイソレータや光サーキュレータ等に使用されるファラデー回転子は一般にＬＰＥ法により育成された磁性ガーネット単結晶から作製される。ＬＰＥ法で用いられる溶媒にはＢ_２Ｏ_３やＢｉ_２Ｏ_３等と共にＰｂＯが使われており、このため磁性ガーネット単結晶の育成時に結晶中に少量の鉛が混入する。従来、通信用光デバイスでは化学式Ｂｉ_{３−ｘ−ｙ}Ｍ１_ｘＰｂ_ｙＦｅ_{５−ｚ−ｗ}Ｍ２_ｚＭ３_ｗＯ_１２において、Ｐｂの量ｙが０．０３〜０．０６程度である磁性ガーネット単結晶をファラデー回転子の材料にしている。 A Faraday rotator used for an optical isolator for communication, an optical circulator, or the like is generally made from a magnetic garnet single crystal grown by the LPE method. As a solvent used in the LPE method, PbO is used together with B ₂ O ₃ , Bi ₂ O _{3, and the} like, so that a small amount of lead is mixed in the crystal when growing the magnetic garnet single crystal. Conventionally, in the chemical formula _Bi _{_3-x-y} _M1 in communication optical device _{_{x Pb y Fe 5-z-}} w M2 z M3 w O 12, the magnetic garnet single amount of Pb y is about 0.03 to 0.06 The crystal is used as the material for the Faraday rotator.

特開２００１−０４４０２６号公報JP 2001-044026 A 特開２００１−０４４０２７号公報JP 2001-044027 A

ところが近年の環境保護運動の高まりと共に、全ての工業製品で環境負荷物質である鉛の含有量を削減させる努力がなされている。従って、ＬＰＥ法により育成する磁性ガーネット単結晶においても、少量ではあるが混入する鉛が環境汚染の要因になり得るとして問題になってきた。そこでファラデー回転子を構成する材料である磁性ガーネット単結晶に含有する鉛の量を削減する必要が生じている。 However, with the recent increase in environmental protection movement, efforts are being made to reduce the content of lead, which is an environmentally hazardous substance, in all industrial products. Therefore, even in a magnetic garnet single crystal grown by the LPE method, a small amount of lead mixed in has become a problem because it can cause environmental pollution. Therefore, it is necessary to reduce the amount of lead contained in the magnetic garnet single crystal that is a material constituting the Faraday rotator.

本発明の目的は、鉛の含有量を削減した磁性ガーネット単結晶及びそれを用いた光学素子並びに磁性ガーネット単結晶の製造方法を提供することにある。 An object of the present invention is to provide a magnetic garnet single crystal with reduced lead content, an optical element using the same, and a method for producing the magnetic garnet single crystal.

上記目的は、液相エピタキシャル成長法により育成され、化学式Ｂｉ_ｘＮａ_ｙＰｂ_ｚＭ１_{３−ｘ−ｙ−ｚ}Ｆｅ_５−ｗＭ２_ｗＯ_１２（式中のＭ１はＹ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ、Ｌｕから選択される少なくとも１種類以上の元素、Ｍ２はＧａ、Ａｌ、Ｉｎ、Ｔｉ、Ｇｅ、Ｓｉ、Ｐｔから選択される少なくとも１種類以上の元素であり、０．５＜ｘ≦２．０、０＜ｙ≦０．８、０≦ｚ＜０．０１、０．１９≦３−ｘ−ｙ−ｚ＜２．５、０≦ｗ≦１．６）で示されることを特徴とする磁性ガーネット単結晶によって達成される。
上記本発明の磁性ガーネット単結晶であって、前記ｙは０＜ｙ≦０．０５であることを特徴とする。 The above object is grown by a liquid phase epitaxial growth method, and has the chemical formula Bi _x Na _y Pb _z M1 _3-x-yz Fe _5-w M2 _w O ₁₂ (where M1 is Y, Sm, Eu, Gd, Tb , Dy, Ho, Er, Tm, Yb, Lu, and at least one element selected from M2, and M2 is at least one element selected from Ga, Al, In, Ti, Ge, Si, Pt 0.5 <x ≦ 2.0, 0 <y ≦ 0.8, 0 ≦ z <0.01, 0.19 ≦ 3-xyz <2.5, 0 ≦ w ≦ 1.6 It is achieved by a magnetic garnet single crystal characterized by the following.
The magnetic garnet single crystal of the present invention is characterized in that y is 0 <y ≦ 0.05.

また、上記目的は、上記本発明の磁性ガーネット単結晶で形成されることを特徴とする光学素子により達成される。
さらに上記目的は、Ｎａを含む融液を生成し、前記融液を用いて液相エピタキシャル成長法により磁性ガーネット単結晶を育成することを特徴とする磁性ガーネット単結晶の製造方法により達成される。 The above object is achieved by an optical element formed of the magnetic garnet single crystal of the present invention.
Further, the above object is achieved by a method for producing a magnetic garnet single crystal, wherein a melt containing Na is produced, and a magnetic garnet single crystal is grown by liquid phase epitaxial growth using the melt.

本発明によれば、ファラデー回転子に用いられる磁性ガーネット単結晶に含まれるＰｂ量を削減し、あるいは完全に除去することができる。 According to the present invention, the amount of Pb contained in the magnetic garnet single crystal used for the Faraday rotator can be reduced or completely removed.

本発明の一実施の形態による磁性ガーネット単結晶及びそれを用いた光学素子並びに磁性ガーネット単結晶の製造方法について説明する。液相エピタキシャル法で磁性ガーネット単結晶膜の育成に使用する溶媒には通常、ＰｂＯ及び、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３が用いられる。Ｂｉはファラデー回転子に使用される磁性ガーネット単結晶の主要な構成元素でもあり、溶媒と溶質の両方の役割を兼ねている。そして主な溶質には各種希土類元素の酸化物、Ｆｅ_２Ｏ_３、及びＦｅと置換できる非磁性元素の酸化物が用いられる。本願における希土類元素は、単独で安定してＦｅとガーネット単結晶を作ることができるＹ、Ｓｍ、Ｅｕ、Ｇｄ、Ｔｂ、Ｄｙ、Ｈｏ、Ｅｒ、Ｔｍ、Ｙｂ、Ｌｕなどである。また、Ｆｅと置換できる非磁性元素は、Ｇａ、Ａｌ、Ｉｎ、Ｔｉ、Ｇｅ、Ｓｉ、Ｐｔなどである。 A magnetic garnet single crystal according to an embodiment of the present invention, an optical element using the same, and a method for producing a magnetic garnet single crystal will be described. Usually, PbO, B ₂ O ₃ , and Bi ₂ O ₃ are used as the solvent used for growing the magnetic garnet single crystal film by the liquid phase epitaxial method. Bi is also a main constituent element of the magnetic garnet single crystal used for the Faraday rotator, and serves as both a solvent and a solute. As main solutes, oxides of various rare earth elements, Fe ₂ O ₃ , and oxides of nonmagnetic elements that can replace Fe are used. The rare earth elements in the present application are Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and the like that can stably form Fe and garnet single crystals independently. Nonmagnetic elements that can replace Fe are Ga, Al, In, Ti, Ge, Si, Pt, and the like.

図１は、本実施の形態における磁性ガーネット単結晶に入り得る各元素の価数とイオン半径とを示している。Ｐｂは２価の電荷を持つカチオン（陽イオン）の状態で単結晶育成中に磁性ガーネット単結晶膜に入る。磁性ガーネット単結晶を構成するＢｉや希土類元素のカチオンの電荷は基本的に３価であるため、２価の電荷を持つＰｂのカチオンがガーネット単結晶中に入ると、電荷のバランスが崩れることになる。そこでガーネット単結晶に入り得る４価の電荷を持つカチオンが融液中に存在すると、そのカチオンはＰｂカチオンの２価の電荷を補償するようにガーネット単結晶に取り込まれる。なおＰｂはイオン半径が希土類元素と比べて大きいため、溶液中に占める割合に比べてわずかな量が希土類鉄ガーネット単結晶に入るだけである。 FIG. 1 shows the valence and ion radius of each element that can enter the magnetic garnet single crystal in the present embodiment. Pb enters a magnetic garnet single crystal film during single crystal growth in the form of a cation (cation) having a divalent charge. Since the charges of Bi and rare earth cations constituting the magnetic garnet single crystal are basically trivalent, if the Pb cation having a divalent charge enters the garnet single crystal, the charge balance will be lost. Become. Therefore, when a cation having a tetravalent charge that can enter the garnet single crystal is present in the melt, the cation is incorporated into the garnet single crystal so as to compensate for the divalent charge of the Pb cation. Since Pb has a larger ionic radius than rare earth elements, only a small amount of Pb enters the rare earth iron garnet single crystal compared to the proportion in the solution.

Ｎａは１価の電荷を持つカチオンの状態で単結晶育成中に磁性ガーネット単結晶膜に入る。Ｐｂと同様に、４価の電荷を持つカチオンを当該磁性ガーネット単結晶に取り込むことにより、磁性ガーネット単結晶に入ったＮａの１価の電荷を補償することが可能である。Ｎａのイオン半径は通常の希土類元素よりは大きいがＰｂよりは小さい。そのためＮａは、磁性ガーネット単結晶内に希土類元素よりは入り難いがＰｂより安定的に入り易い。 Na enters the magnetic garnet single crystal film during single crystal growth in the form of a cation having a monovalent charge. Similarly to Pb, by incorporating a cation having a tetravalent charge into the magnetic garnet single crystal, it is possible to compensate for the monovalent charge of Na contained in the magnetic garnet single crystal. The ionic radius of Na is larger than that of ordinary rare earth elements but smaller than that of Pb. Therefore, Na is less likely to enter the magnetic garnet single crystal than the rare earth element, but is more likely to enter stably than Pb.

ＮａとＰｂは両方とも、磁性ガーネット単結晶中で希土類元素と比べ電荷の価数が小さく、またイオン半径が大きな元素である。但し、Ｎａのイオン半径の方がＰｂより希土類元素のイオン半径に近いため、ＰｂとＮａが同時に単結晶育成用の融液中に存在する場合には、Ｎａの方がＰｂよりガーネット単結晶に入り易い傾向がある。ＮａカチオンとＰｂカチオンの価数は希土類元素のカチオンの価数より小さい点では同じ特性を有しているが、Ｎａは優先的にガーネット単結晶に入るためＰｂがガーネット単結晶に入るのを妨害する効果を有する。従って、Ｎａを磁性ガーネット単結晶に加えることにより、ガーネット単結晶中に入るＰｂの量を化学式で０．０１未満に削減させることができる。
２００６年７月には、電気電子機器における有害物質の使用を規制するＲｏＨＳ（ＲｅｓｔｒｉｃｔｉｏｎｏｎＨａｚａｒｄｏｕｓＳｕｂｓｔａｎｃｅｓ；有害物質使用制限）指令がＥＵ（欧州連合）で施行される。ＲｏＨＳ指令で規定されるＰｂの最大許容量は、重量比で１０００ｐｐｍである。本実施の形態による磁性ガーネット単結晶の組成においては、Ｐｂの量が化学式で０．０１未満であれば上記の最大許容量以下にすることも可能になる。従って本実施の形態によれば、ＲｏＨＳ指令に適合した光学素子が得られる。 Both Na and Pb are elements in the magnetic garnet single crystal that have a smaller charge valence and a larger ionic radius than rare earth elements. However, since the ionic radius of Na is closer to that of the rare earth element than Pb, when Pb and Na are simultaneously present in the melt for growing a single crystal, Na is more garnet single crystal than Pb. There is a tendency to enter easily. Na cation and Pb cation have the same characteristics in that they are smaller than the valence of rare earth cations, but Na preferentially enters the garnet single crystal and prevents Pb from entering the garnet single crystal. Has the effect of Therefore, by adding Na to the magnetic garnet single crystal, the amount of Pb entering the garnet single crystal can be reduced to less than 0.01 in chemical formula.
In July 2006, the RoHS (Restriction on Hazardous Substances) Directive, which regulates the use of hazardous substances in electrical and electronic equipment, will come into effect in the EU (European Union). The maximum allowable amount of Pb defined by the RoHS directive is 1000 ppm by weight. In the composition of the magnetic garnet single crystal according to the present embodiment, if the amount of Pb is less than 0.01 in the chemical formula, it is possible to make it not more than the above maximum allowable amount. Therefore, according to the present embodiment, an optical element conforming to the RoHS command can be obtained.

またＮａと酸素とを含有する物質は他の酸化物と比べて低い温度で溶解するものが多いため、磁性ガーネット単結晶を育成する際の溶媒としても有効である。例えばＮａＯＨを含む溶媒で育成されたＮａが入った磁性ガーネット単結晶は、欠陥や割れのない優れた品質が得られる。そのため溶媒の材料からＰｂＯを除外し、Ｎａを含む物質とＢｉ_２Ｏ_３及びＢ_２Ｏ_３を溶媒に用いて、Ｎａの入った磁性ガーネット単結晶を育成することにより、Ｐｂが完全に除かれた磁性ガーネット単結晶を得ることが可能である。 In addition, since many substances containing Na and oxygen dissolve at a lower temperature than other oxides, they are also effective as solvents for growing magnetic garnet single crystals. For example, a magnetic garnet single crystal containing Na grown with a solvent containing NaOH can have excellent quality without defects or cracks. Therefore, by removing PbO from the solvent material and growing a magnetic garnet single crystal containing Na using a substance containing Na and Bi ₂ O ₃ and B ₂ O ₃ as a solvent, Pb is completely removed. It is possible to obtain a magnetic garnet single crystal.

Ｎａを含む溶媒で磁性ガーネット単結晶を育成する場合には、Ｎａを含まない溶媒に比して溶液の過飽和状態をより安定に保つことができる。そのためＢｉは化学式で２．０程度まで安定してガーネット単結晶に入ることができる。またファラデー回転子として十分な回転係数（ｄｅｇ．／μｍ）を得るためには、Ｂｉは化学式で０．５以上は必要である。 When a magnetic garnet single crystal is grown with a solvent containing Na, the supersaturated state of the solution can be kept more stable than a solvent containing no Na. Therefore, Bi can enter the garnet single crystal stably in a chemical formula up to about 2.0. In order to obtain a sufficient rotation coefficient (deg./μm) as a Faraday rotator, Bi must be 0.5 or more in chemical formula.

非磁性元素が化学式で１．６より多くＦｅと置換して磁性ガーネット単結晶に入ってくると、磁性ガーネット単結晶のキュリー点が室温付近の温度値まで下がり、ファラデー回転子として使えなくなる。そのためＦｅと置換される非磁性元素は化学式で１．６以下とすることが必要となる。 When a nonmagnetic element is substituted with more than 1.6 in the chemical formula and enters the magnetic garnet single crystal, the Curie point of the magnetic garnet single crystal falls to a temperature value near room temperature and cannot be used as a Faraday rotator. Therefore, the nonmagnetic element substituted for Fe must be 1.6 or less in chemical formula.

Ｎａがガーネット単結晶に多く入るには、ガーネット単結晶の電荷のバランスを取るために、Ｔｉ、Ｇｅ、Ｓｉ、Ｐｔなどの４価の電荷が安定なイオンと共にガーネット単結晶に取り込まれる必要がある。Ｎａが化学式で０．８以上ガーネット単結晶に入るには、４価の電荷で安定なイオンが化学式で１．６以上ガーネット単結晶に入る必要がある。Ｆｅと置換可能なＴｉ、Ｇｅ、Ｓｉ、Ｐｔなどの元素が化学式で１．６以上あると、磁性ガーネット単結晶はそのキュリー点が室温以下になってしまいファラデー回転子として使えなくなる。そのためＮａのガーネット単結晶に入る量は化学式で０．８までとすることが必要である。
また別の観点として、ガーネット単結晶に入るＮａが多くなると、当該ガーネット単結晶を用いて作製されたファラデー回転子の挿入損失が増加してしまう。従って、挿入損失の小さいファラデー回転子を得るためには、Ｎａのガーネット単結晶に入る量は化学式で０．０５以下であることが望ましい。 In order for Na to enter a large amount in the garnet single crystal, in order to balance the charge of the garnet single crystal, it is necessary to incorporate tetravalent charges such as Ti, Ge, Si, and Pt into the garnet single crystal together with stable ions. . In order for Na to enter a garnet single crystal with a chemical formula of 0.8 or more, it is necessary that stable ions with a tetravalent charge enter the garnet single crystal with a chemical formula of 1.6 or more. If elements such as Ti, Ge, Si, and Pt that can be substituted for Fe are 1.6 or more in chemical formula, the magnetic garnet single crystal cannot be used as a Faraday rotator because its Curie point falls below room temperature. Therefore, the amount of Na entering the garnet single crystal must be up to 0.8 in the chemical formula.
As another point of view, when the amount of Na entering the garnet single crystal increases, the insertion loss of the Faraday rotator manufactured using the garnet single crystal increases. Therefore, in order to obtain a Faraday rotator with small insertion loss, the amount of Na entering the garnet single crystal is desirably 0.05 or less in chemical formula.

Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、Ｐｍなどの元素は単独ではＦｅとガーネット単結晶を作ることは困難であるが、ガーネット単結晶の構成元素の一部として入ることは可能である。 La, Ce, Pr, Nd, and Pm alone are difficult to form a single crystal of Fe and garnet by themselves, but can be included as a part of constituent elements of a garnet single crystal.

以下、本実施の形態による磁性ガーネット単結晶及びそれを用いた光学素子並びに磁性ガーネット単結晶の製造方法について、図１を参照しつつ実施例１乃至１２を用いて具体的に説明する。
（実施例１）
図２は、磁性ガーネット単結晶の製造工程の一部を示している。図２に示すように、金製のルツボ４にＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。９５０℃まで炉温を上げてルツボ４内の材料を溶解し、金製の攪拌用冶具を使用して融液８を攪拌した。 Hereinafter, a magnetic garnet single crystal according to the present embodiment, an optical element using the same, and a method for producing the magnetic garnet single crystal will be specifically described with reference to FIGS.
Example 1
FIG. 2 shows a part of the manufacturing process of the magnetic garnet single crystal. As shown in FIG. 2, the gold crucible 4 was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. The furnace temperature was raised to 950 ° C., the material in the crucible 4 was dissolved, and the melt 8 was stirred using a gold stirring jig.

磁性ガーネット単結晶膜を育成するための基板には、引き上げ法により育成したガーネット単結晶のインゴットから作製された単結晶ウェハを用いる。本実施例では、単結晶育成用基板としてＣａＭｇＺｒ置換ＧＧＧ（ガドリニウム・ガリウム・ガーネット）単結晶基板（（ＧｄＣａ）_３（ＧａＭｇＺｒ）_５Ｏ_１２）１０を用いている。 As a substrate for growing a magnetic garnet single crystal film, a single crystal wafer made from a garnet single crystal ingot grown by a pulling method is used. In this embodiment, a CaMgZr-substituted GGG (gadolinium gallium garnet) single crystal substrate ((GdCa) ₃ (GaMgZr) ₅ O ₁₂ ) 10 is used as a single crystal growth substrate.

ＣａＭｇＺｒ置換ＧＧＧ基板１０を金製の固定冶具２に取り付けて炉内に投入し、７４５℃まで炉温を下げてから基板１０の片面を融液８に接触させてエピタキシャル成長を４０時間行った。膜厚５００μｍのＢｉ置換希土類鉄ガーネット単結晶（磁性ガーネット単結晶）膜１２が得られた。育成した単結晶を蛍光Ｘ線分析法により組成分析したところ、組成はＢｉ_１．３０Ｇｄ_１．２０Ｙｂ_０．５０Ｆｅ_５．００Ｏ_１２であり、Ｎａは検出できたが組成を確定することはできなかった。また、Ｐｂは検出されなかった。次にＩＣＰ（ＩｎｄｕｃｔｉｖｅｌｙＣｏｕｐｌｅｄＰｌａｓｍａ；高周波誘導結合プラズマ）分析法で詳しく組成を評価したところ、Ｎａの含有量を確定できた。その結果、磁性ガーネット単結晶の化学式は、（ＢｉＧｄＹｂ）_{２．９９８}Ｎａ_{０．００２}Ｆｅ_{５．０００}Ｏ_１２であることが分かった。従ってこの単結晶にＰｂは含有されてないことが確認された。育成した単結晶膜１２を加工して、波長１．５５μｍの光に対してファラデー回転角４５ｄｅｇ（度）となる単結晶板を作製した。その単結晶板の研磨面に無反射コート（反射防止膜）を成膜してファラデー回転子とした。波長１．５５μｍの光を入射させて、作製した回転子の光学特性を評価したところ、ファラデー回転子として問題のない特性であった。 The CaMgZr-substituted GGG substrate 10 was attached to the gold fixture 2 and placed in the furnace. After the furnace temperature was lowered to 745 ° C., one side of the substrate 10 was brought into contact with the melt 8 and epitaxial growth was performed for 40 hours. A Bi-substituted rare earth iron garnet single crystal (magnetic garnet single crystal) film 12 having a thickness of 500 μm was obtained. Composition analysis of the grown single crystal by X-ray fluorescence analysis revealed that the composition was Bi _1.30 Gd _1.20 Yb _0.50 Fe _5.00 O ₁₂ and Na was detected but the composition was determined. I couldn't. Moreover, Pb was not detected. Next, when the composition was evaluated in detail by ICP (Inductively Coupled Plasma) analysis, the content of Na could be determined. As a result, it was found that the chemical formula of the magnetic garnet single crystal was (BiGdYb) _2.998 Na _0.002 Fe _5.000 O ₁₂ . Therefore, it was confirmed that this single crystal did not contain Pb. The grown single crystal film 12 was processed to produce a single crystal plate having a Faraday rotation angle of 45 deg (degrees) with respect to light having a wavelength of 1.55 μm. A non-reflective coating (antireflection film) was formed on the polished surface of the single crystal plate to form a Faraday rotator. When the optical characteristics of the manufactured rotor were evaluated by making light having a wavelength of 1.55 μm incident, the characteristics were satisfactory as a Faraday rotator.

（実施例２）
金製のルツボ４にＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、Ｂ_２Ｏ_３、ＧｅＯ_２、Ｂｉ_２
Ｏ_３、ＰｂＯ、ＮａＯＨを充填して、電気炉に配置した。９５０℃まで炉温を上げてルツボ４内の材料を溶解し、金製の攪拌用冶具を使用して融液８を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板１０を金製の固定冶具２に取り付けて炉内に投入し、７４５℃まで炉温を下げてから基板１０の片面を融液８に接触させてエピタキシャル成長を４０時間行った。膜厚５００μｍの磁性ガーネット単結晶膜１２が得られた。育成した単結晶を蛍光Ｘ線分析法により組成分析したところ、組成はＢｉ_１．３０Ｇｄ_１．１８Ｙｂ_０．５０Ｎａ_０．０２Ｆｅ_４．９５Ｇｅ_０．０５Ｏ_１２であり、Ｐｂは検出されたが組成を確定させることはできなかった。次にＩＣＰ分析法で詳しく組成を評価したところ、Ｐｂの含有量を確定できた。その結果、磁性ガーネット単結晶の化学式は（ＢｉＧｄＹｂＮａ）_{２．９９１}Ｐｂ_{０．００９}（ＦｅＧｅ）_{５．０００}Ｏ_１２であることが分かった。Ｐｂの含有量が非常に少なくなっていることが確認された。育成した単結晶膜１２を加工して、波長１．５５μｍの光に対して回転角４５ｄｅｇとなる単結晶板を作製した。その単結晶板の研磨面に無反射コートを成膜してファラデー回転子とした。波長１．５５μｍの光を入射させて、作製した回転子の光学特性を評価したところ、ファラデー回転子として問題のない特性であった。 (Example 2)
Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , B ₂ O ₃ , GeO ₂ , Bi ₂ are placed on the gold crucible 4.
Filled with O ₃ , PbO and NaOH and placed in an electric furnace. The furnace temperature was raised to 950 ° C., the material in the crucible 4 was dissolved, and the melt 8 was stirred using a gold stirring jig. The CaMgZr-substituted GGG substrate 10 was attached to the gold fixture 2 and placed in the furnace. After the furnace temperature was lowered to 745 ° C., one side of the substrate 10 was brought into contact with the melt 8 and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film 12 having a thickness of 500 μm was obtained. The composition of the grown single crystal was analyzed by fluorescent X-ray analysis. As a result, the composition was Bi _1.30 Gd _1.18 Yb _0.50 Na _0.02 Fe _4.95 Ge _0.05 O ₁₂ and Pb was detected. However, the composition could not be determined. Next, when the composition was evaluated in detail by the ICP analysis method, the Pb content was confirmed. As a result, the chemical formula of the magnetic garnet single crystal was found to be _{_{_{_{5.000 O 12 (BiGdYbNa) 2.991 Pb}}}} 0.009 (FeGe). It was confirmed that the Pb content was very low. The grown single crystal film 12 was processed to produce a single crystal plate having a rotation angle of 45 deg with respect to light having a wavelength of 1.55 μm. A non-reflective coating was formed on the polished surface of the single crystal plate to form a Faraday rotator. When the optical characteristics of the manufactured rotor were evaluated by making light having a wavelength of 1.55 μm incident, the characteristics were satisfactory as a Faraday rotator.

（実施例３）
金製のルツボ４にＴｂ_４Ｏ_７、Ｈｏ_２Ｏ_３、Ｆｅ_２Ｏ_３、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。９５０℃まで炉温を上げてルツボ４内の材料を溶解し、金製の攪拌用冶具を使用して融液８を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板１０を金製の固定冶具２に取り付けて炉内に投入し、７７５℃まで炉温を下げてから基板１０の片面を融液８に接触させてエピタキシャル成長を４０時間行った。膜厚５１０μｍの磁性ガーネット単結晶膜１２が得られた。育成した単結晶を蛍光Ｘ線分析法により組成分析したところ、組成はＢｉ_１．０４Ｔｂ_１．６７Ｈｏ_０．２９Ｆｅ_５．００Ｏ_１２であり、Ｎａは検出されたが組成を確定させることはできなかった。次にＩＣＰ分析法で詳しく組成を評価したところ、Ｎａの含有量を確定できた。その結果、磁性ガーネット単結晶の化学式は（ＢｉＴｂＨｏ）_{２．９９８}Ｎａ_{０．００２}Ｆｅ_{５．０００}Ｏ_１２であることが分かった。この単結晶にＰｂは含有されていないことが確認された。育成した単結晶膜１２を加工して、波長１．５５μｍの光に対して回転角４５ｄｅｇとなる単結晶板を作製した。その単結晶板の研磨面に無反射コートを成膜してファラデー回転子とした。波長１．５５μｍの光を入射させて、作製した回転子の光学特性を評価したところ、ファラデー回転子として問題のない特性であった。 (Example 3)
A gold crucible 4 was filled with Tb ₄ O ₇ , Ho ₂ O ₃ , Fe ₂ O ₃ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. The furnace temperature was raised to 950 ° C., the material in the crucible 4 was dissolved, and the melt 8 was stirred using a gold stirring jig. The CaMgZr-substituted GGG substrate 10 was attached to the gold fixture 2 and placed in the furnace. After the furnace temperature was lowered to 775 ° C., one side of the substrate 10 was brought into contact with the melt 8 and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film 12 having a thickness of 510 μm was obtained. Composition analysis of the grown single crystal by X-ray fluorescence analysis revealed that the composition was Bi _1.04 Tb _1.67 Ho _0.29 Fe _5.00 O ₁₂ and Na was detected but the composition was confirmed. I couldn't. Next, when the composition was evaluated in detail by ICP analysis, the content of Na could be determined. As a result, it was found that the chemical formula of the magnetic garnet single crystal was (BiTbHo) _2.998 Na _0.002 Fe _5.000 O ₁₂ . It was confirmed that this single crystal did not contain Pb. The grown single crystal film 12 was processed to produce a single crystal plate having a rotation angle of 45 deg with respect to light having a wavelength of 1.55 μm. A non-reflective coating was formed on the polished surface of the single crystal plate to form a Faraday rotator. When the optical characteristics of the manufactured rotor were evaluated by making light having a wavelength of 1.55 μm incident, the characteristics were satisfactory as a Faraday rotator.

（実施例４）
金製のルツボ４にＥｕ_２Ｏ_３、Ｌｕ_２Ｏ_３、Ｆｅ_２Ｏ_３、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。９５０℃まで炉温を上げてルツボ４内の材料を溶解し、金製の攪拌用冶具を使用して融液８を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板１０を金製の固定冶具２に取り付けて炉内に投入し、８１０℃まで炉温を下げてから基板１０の片面を融液８に接触させてエピタキシャル成長を３５時間行った。膜厚４５０μｍの磁性ガーネット単結晶膜１２が得られた。育成した単結晶を蛍光Ｘ線分析法により組成分析したところ、組成はＢｉ_０．７６Ｅｕ_１．７０Ｌｕ_０．５４Ｆｅ_５．００Ｏ_１２であり、Ｎａは検出されたが組成を確定させることはできなかった。次にＩＣＰ分析法で詳しく組成を評価したところ、Ｎａの含有量を確定できた。その結果、磁性ガーネット単結晶の化学式は（ＢｉＥｕＬｕ）_{２．９９８}Ｎａ_{０．００２}Ｆｅ_{５．０００}Ｏ_１２であることが分かった。この単結晶にＰｂは含有されていないことが確認された。育成した単結晶膜１２を加工して、波長１．３１μｍの光に対して回転角４５ｄｅｇとなる単結晶板を作製した。その単結晶板の研磨面に無反射コートを成膜してファラデー回転子とした。波長１．３１μｍの光を入射させて、作製した回転子の光学特性を評価したところ、ファラデー回転子として問題のない特性であった。 Example 4
A gold crucible 4 was filled with Eu ₂ O ₃ , Lu ₂ O ₃ , Fe ₂ O ₃ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. The furnace temperature was raised to 950 ° C., the material in the crucible 4 was dissolved, and the melt 8 was stirred using a gold stirring jig. The CaMgZr-substituted GGG substrate 10 was attached to the gold fixture 2 and placed in the furnace. After the furnace temperature was lowered to 810 ° C., one side of the substrate 10 was brought into contact with the melt 8 and epitaxial growth was performed for 35 hours. A magnetic garnet single crystal film 12 having a thickness of 450 μm was obtained. Composition analysis of the grown single crystal by fluorescent X-ray analysis revealed that the composition was Bi _0.76 Eu _1.70 Lu _0.54 Fe _5.00 O ₁₂ and Na was detected but the composition was confirmed. I couldn't. Next, when the composition was evaluated in detail by ICP analysis, the content of Na could be determined. As a result, it was found that the chemical formula of the magnetic garnet single crystal was (BiEuLu) _2.998 Na _0.002 Fe _5.000 O ₁₂ . It was confirmed that this single crystal did not contain Pb. The grown single crystal film 12 was processed to produce a single crystal plate having a rotation angle of 45 deg with respect to light having a wavelength of 1.31 μm. A non-reflective coating was formed on the polished surface of the single crystal plate to form a Faraday rotator. When the optical characteristics of the manufactured rotor were evaluated by making light having a wavelength of 1.31 μm incident, the characteristics were satisfactory as a Faraday rotator.

（実施例５）
金製のルツボ４にＤｙ_２Ｏ_３、Ｙ_２Ｏ_３、Ｓｍ_２Ｏ_３、Ｆｅ_２Ｏ_３、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。９５０℃まで炉温を上げてルツボ４内の材料を溶解し、金製の攪拌用冶具を使用して融液８を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板１０を金製の固定冶具２に取り付けて炉内に投入し、７４５℃まで炉温を下げてから基板１０の片面を融液８に接触させてエピタキシャル成長を４０時間行った。膜厚４５０μｍの磁性ガーネット単結晶膜１２が得られた。育成した単結晶を蛍光Ｘ線分析法により組成分析したところ、組成はＢｉ_１．２９Ｄｙ_１．２０Ｙ_０．４１Ｓｍ_０．１０Ｆｅ_５．００Ｏ_１２であり、Ｎａは検出されたが組成を確定させることはできなかった。次にＩＣＰ分析法で詳しく組成を評価したところ、Ｎａの含有量を確定できた。その結果、磁性ガーネット単結晶の化学式は（ＢｉＤｙＹＳｍ）_{２．９９８}Ｎａ_{０．００２}Ｆｅ_{５．０００}Ｏ_１２であることが分かった。この単結晶にＰｂは含有されていないことが確認された。育成した単結晶膜１２を加工して、波長１．５５μｍの光に対して回転角４５ｄｅｇとなる単結晶板を作製した。その単結晶板の研磨面に無反射コートを成膜してファラデー回転子とした。波長１．５５μｍの光を入射させて、作製した回転子の光学特性を評価したところ、ファラデー回転子として問題のない特性であった。 (Example 5)
A gold crucible 4 was filled with Dy ₂ O ₃ , Y ₂ O ₃ , Sm ₂ O ₃ , Fe ₂ O ₃ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. The furnace temperature was raised to 950 ° C., the material in the crucible 4 was dissolved, and the melt 8 was stirred using a gold stirring jig. The CaMgZr-substituted GGG substrate 10 was attached to the gold fixture 2 and placed in the furnace. After the furnace temperature was lowered to 745 ° C., one side of the substrate 10 was brought into contact with the melt 8 and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film 12 having a thickness of 450 μm was obtained. When a grown single crystal was compositionally analyzed by X-ray fluorescence analysis, the composition is a _{_{_{_{Bi 1.29 Dy 1.20 Y 0.41 Sm 0.10}}}} Fe 5.00 O 12, Na has been detected composition Could not be confirmed. Next, when the composition was evaluated in detail by ICP analysis, the content of Na could be determined. As a result, it was found that the chemical formula of the magnetic garnet single crystal was (BiDyYSm) _2.998 Na _0.002 Fe _5.000 O ₁₂ . It was confirmed that this single crystal did not contain Pb. The grown single crystal film 12 was processed to produce a single crystal plate having a rotation angle of 45 deg with respect to light having a wavelength of 1.55 μm. A non-reflective coating was formed on the polished surface of the single crystal plate to form a Faraday rotator. When the optical characteristics of the manufactured rotor were evaluated by making light having a wavelength of 1.55 μm incident, the characteristics were satisfactory as a Faraday rotator.

（実施例６）
金製のルツボ４にＧｄ_２Ｏ_３、Ｅｒ_２Ｏ_３、Ｔｍ_２Ｏ_３、Ｆｅ_２Ｏ_３、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。９５０℃まで炉温を上げてルツボ４内の材料を溶解し、金製の攪拌用冶具を使用して融液８を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板１０を金製の固定冶具２に取り付けて炉内に投入し、７１０℃まで炉温を下げてから基板１０の片面を融液８に接触させてエピタキシャル成長を２０時間行った。膜厚３００μｍの磁性ガーネット単結晶膜１２が得られた。育成した単結晶を蛍光Ｘ線分析法により組成分析したところ、組成はＢｉ_１．６０Ｇｄ_０．２７Ｅｒ_０．７３Ｔｍ_０．４０Ｆｅ_５．００Ｏ_１２であり、Ｎａは検出されたが組成を確定させることはできなかった。次にＩＣＰ分析法で詳しく組成を評価したところ、Ｎａの含有量を確定できた。その結果、磁性ガーネット単結晶の化学式は（ＢｉＧｄＥｒＴｍ）_{２．９９８}Ｎａ_{０．００２}Ｆｅ_{５．０００}Ｏ_１２であることが分かった。この単結晶にＰｂは含有されていないことが確認された。育成した単結晶膜１２を加工して、波長１．３１μｍの光に対して回転角４５ｄｅｇとなる単結晶板を作製した。その単結晶板の研磨面に無反射コートを成膜してファラデー回転子とした。波長１．３１μｍの光を入射させて、作製した回転子の光学特性を評価したところ、ファラデー回転子として使用可能な特性であった。 (Example 6)
A gold crucible 4 was filled with Gd ₂ O ₃ , Er ₂ O ₃ , Tm ₂ O ₃ , Fe ₂ O ₃ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. The furnace temperature was raised to 950 ° C., the material in the crucible 4 was dissolved, and the melt 8 was stirred using a gold stirring jig. The CaMgZr-substituted GGG substrate 10 was attached to the gold fixture 2 and placed in the furnace. After the furnace temperature was lowered to 710 ° C., one side of the substrate 10 was brought into contact with the melt 8 and epitaxial growth was performed for 20 hours. A magnetic garnet single crystal film 12 having a thickness of 300 μm was obtained. Composition analysis of the grown single crystal by X-ray fluorescence analysis revealed that the composition was Bi _1.60 Gd _0.27 Er _0.73 Tm _0.40 Fe _5.00 O ₁₂ and Na was detected but the composition Could not be confirmed. Next, when the composition was evaluated in detail by ICP analysis, the content of Na could be determined. As a result, it was found that the chemical formula of the magnetic garnet single crystal was (BiGdErTm) _2.998 Na _0.002 Fe _5.000 O ₁₂ . It was confirmed that this single crystal did not contain Pb. The grown single crystal film 12 was processed to produce a single crystal plate having a rotation angle of 45 deg with respect to light having a wavelength of 1.31 μm. A non-reflective coating was formed on the polished surface of the single crystal plate to form a Faraday rotator. When light having a wavelength of 1.31 μm was incident and the optical characteristics of the manufactured rotor were evaluated, the characteristics were usable as a Faraday rotator.

（実施例７）
金製のルツボ４にＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、Ｇａ_２Ｏ_３、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。９５０℃まで炉温を上げてルツボ４内の材料を溶解し、金製の攪拌用冶具を使用して融液８を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板１０を金製の固定冶具２に取り付けて炉内に投入し、７８６℃まで炉温を下げてから基板１０の片面を融液８に接触させてエピタキシャル成長を４０時間行った。膜厚５５０μｍの磁性ガーネット単結晶膜１２が得られた。育成した単結晶を蛍光Ｘ線分析法により組成分析したところ、組成はＢｉ_０．９５Ｇｄ_１．６７Ｙｂ_０．３８Ｆｅ_４．８０Ｇａ_０．２０Ｏ_１２であり、Ｎａは検出されたが組成を確定させることはできなかった。次にＩＣＰ分析法で詳しく組成を評価したところ、Ｎａの含有量を確定できた。その結果、磁性ガーネット単結晶の化学式は（ＢｉＧｄＹｂ）_{２．９９８}Ｎａ_{０．００２}（ＦｅＧａ）_{５．０００}Ｏ_１２であることが分かった。この単結晶にＰｂは含有されていないことが確認された。育成した単結晶膜１２を加工して、波長１．５５μｍの光に対して回転角４５ｄｅｇとなる単結晶板を作製した。その単結晶板の研磨面に無反射コートを成膜してファラデー回転子とした。波長１．５５μｍの光を入射させて、作製した回転子の光学特性を評価したところ、ファラデー回転子として問題のない特性であった。 (Example 7)
A gold crucible 4 was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , Ga ₂ O ₃ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. The furnace temperature was raised to 950 ° C., the material in the crucible 4 was dissolved, and the melt 8 was stirred using a gold stirring jig. The CaMgZr-substituted GGG substrate 10 was attached to the gold fixture 2 and placed in the furnace. After the furnace temperature was lowered to 786 ° C., one side of the substrate 10 was brought into contact with the melt 8 and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film 12 having a thickness of 550 μm was obtained. Composition analysis of the grown single crystal by X-ray fluorescence analysis revealed that the composition was Bi _0.95 Gd _1.67 Yb _0.38 Fe _4.80 Ga _0.20 O ₁₂ and Na was detected but the composition Could not be confirmed. Next, when the composition was evaluated in detail by ICP analysis, the content of Na could be determined. As a result, the chemical formula of the magnetic garnet single crystal was found to be _{_{_{_{5.000 O 12 (BiGdYb) 2.998 Na}}}} 0.002 (FeGa). It was confirmed that this single crystal did not contain Pb. The grown single crystal film 12 was processed to produce a single crystal plate having a rotation angle of 45 deg with respect to light having a wavelength of 1.55 μm. A non-reflective coating was formed on the polished surface of the single crystal plate to form a Faraday rotator. When the optical characteristics of the manufactured rotor were evaluated by making light having a wavelength of 1.55 μm incident, the characteristics were satisfactory as a Faraday rotator.

（実施例８）
金製のルツボ４にＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、Ａｌ_２Ｏ_３、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。９５０℃まで炉温を上げてルツボ４内の材料を溶解し、金製の攪拌用冶具を使用して融液８を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板１０を金製の固定冶具２に取り付けて炉内に投入し、７７２℃まで炉温を下げてから基板１０の片面を融液８に接触させてエピタキシャル成長を４０時間行った。膜厚５３０μｍの磁性ガーネット単結晶膜１２が得られた。育成した単結晶を蛍光Ｘ線分析法により組成分析したところ、組成はＢｉ_１．０７Ｇｄ_１．６７Ｙｂ_０．２６Ｆｅ_４．８０Ａｌ_０．２０Ｏ_１２であり、Ｎａは検出されたが組成を確定させることはできなかった。次にＩＣＰ分析法で詳しく組成を評価したところ、Ｎａの含有量を確定できた。その結果、磁性ガーネット単結晶の化学式は（ＢｉＧｄＹｂ）_{２．９９８}Ｎａ_{０．００２}（ＦｅＡｌ）_{５．０００}Ｏ_１２であることが分かった。この単結晶にＰｂは含有されていないことが確認された。育成した単結晶膜１２を加工して、波長１．５５μｍの光に対して回転角４５ｄｅｇとなる単結晶板を作製した。その単結晶板の研磨面に無反射コートを成膜してファラデー回転子とした。波長１．５５μｍの光を入射させて、作製した回転子の光学特性を評価したところ、ファラデー回転子として問題のない特性であった。 (Example 8)
A gold crucible 4 was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , Al ₂ O ₃ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. The furnace temperature was raised to 950 ° C., the material in the crucible 4 was dissolved, and the melt 8 was stirred using a gold stirring jig. The CaMgZr-substituted GGG substrate 10 was attached to a gold fixture 2 and placed in a furnace. After the furnace temperature was lowered to 772 ° C., one side of the substrate 10 was brought into contact with the melt 8 and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film 12 having a film thickness of 530 μm was obtained. The composition of the grown single crystal was analyzed by fluorescent X-ray analysis. The composition was Bi _1.07 Gd _1.67 Yb _0.26 Fe _4.80 Al _0.20 O ₁₂ and Na was detected but the composition Could not be confirmed. Next, when the composition was evaluated in detail by ICP analysis, the content of Na could be determined. As a result, the chemical formula of the magnetic garnet single crystal was found to be _{_{_{_{5.000 O 12 (BiGdYb) 2.998 Na}}}} 0.002 (FeAl). It was confirmed that this single crystal did not contain Pb. The grown single crystal film 12 was processed to produce a single crystal plate having a rotation angle of 45 deg with respect to light having a wavelength of 1.55 μm. A non-reflective coating was formed on the polished surface of the single crystal plate to form a Faraday rotator. When the optical characteristics of the manufactured rotor were evaluated by making light having a wavelength of 1.55 μm incident, the characteristics were satisfactory as a Faraday rotator.

（実施例９）
金製のルツボ４にＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、Ｉｎ_２Ｏ_３、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。９５０℃まで炉温を上げてルツボ４内の材料を溶解し、金製の攪拌用冶具を使用して融液８を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板１０を金製の固定冶具２に取り付けて炉内に投入し、８０５℃まで炉温を下げてから基板１０の片面を融液８に接触させてエピタキシャル成長を４５時間行った。膜厚５００μｍの磁性ガーネット単結晶膜１２が得られた。育成した単結晶を蛍光Ｘ線分析法により組成分析したところ、組成はＢｉ_０．７９Ｇｄ_１．６７Ｙｂ_０．５４Ｆｅ_４．９０Ｉｎ_０．１０Ｏ_１２であり、Ｎａは検出されたが組成を確定させることはできなかった。次にＩＣＰ分析法で詳しく組成を評価したところ、Ｎａの含有量を確定できた。その結果、磁性ガーネット単結晶の化学式は（ＢｉＧｄＹｂ）_{２．９９８}Ｎａ_{０．００２}（ＦｅＩｎ）_{５．０００}Ｏ_１２であることが分かった。この単結晶にＰｂは含有されていないことが確認された。育成した単結晶膜１２を加工して、波長１．３１μｍの光に対して回転角４５ｄｅｇとなる単結晶板を作製した。その単結晶板の研磨面に無反射コートを成膜してファラデー回転子とした。波長１．３１μｍの光を入射させて、作製した回転子の光学特性を評価したところ、ファラデー回転子として問題のない特性であった。 Example 9
Gold crucible 4 was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , In ₂ O ₃ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH, and placed in an electric furnace. The furnace temperature was raised to 950 ° C., the material in the crucible 4 was dissolved, and the melt 8 was stirred using a gold stirring jig. The CaMgZr-substituted GGG substrate 10 was attached to the gold fixture 2 and placed in the furnace. After the furnace temperature was lowered to 805 ° C., one side of the substrate 10 was brought into contact with the melt 8 and epitaxial growth was performed for 45 hours. A magnetic garnet single crystal film 12 having a thickness of 500 μm was obtained. Composition analysis of the grown single crystal by X-ray fluorescence analysis revealed that the composition was Bi _0.79 Gd _1.67 Yb _0.54 Fe _4.90 In _0.10 O ₁₂ and Na was detected but the composition Could not be confirmed. Next, when the composition was evaluated in detail by ICP analysis, the content of Na could be determined. As a result, it was found that the chemical formula of the magnetic garnet single crystal was (BiGdYb) _2.998 Na _0.002 (FeIn) _5.000 O ₁₂ . It was confirmed that this single crystal did not contain Pb. The grown single crystal film 12 was processed to produce a single crystal plate having a rotation angle of 45 deg with respect to light having a wavelength of 1.31 μm. A non-reflective coating was formed on the polished surface of the single crystal plate to form a Faraday rotator. When the optical characteristics of the manufactured rotor were evaluated by making light having a wavelength of 1.31 μm incident, the characteristics were satisfactory as a Faraday rotator.

（実施例１０）
金製のルツボ４にＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、ＧｅＯ_２、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。９５０℃まで炉温を上げてルツボ４内の材料を溶解し、金製の攪拌用冶具を使用して融液８を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板１０を金製の固定冶具２に取り付けて炉内に投入し、７９０℃まで炉温を下げてから基板１０の片面を融液８に接触させてエピタキシャル成長を４２時間行った。膜厚５７０μｍの磁性ガーネット単結晶膜１２が得られた。育成した単結晶を蛍光Ｘ線分析法により組成分析したところ、組成はＢｉ_０．９３Ｇｄ_１．６７Ｙｂ_０．２０Ｎａ_０．２０Ｆｅ_４．６０Ｇｅ_０．４０Ｏ_１２であった。この単結晶にＰｂは含有されていないことが確認された。育成した単結晶膜１２を加工して、波長１．５５μｍの光に対して回転角４５ｄｅｇとなる単結晶板を作製した。その単結晶板の研磨面に無反射コートを成膜してファラデー回転子とした。波長１．５５μｍの光を入射させて、作製した回転子の光学特性を評価したところ、ファラデー回転子として問題のない特性であった。 (Example 10)
A gold crucible 4 was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , GeO ₂ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. The furnace temperature was raised to 950 ° C., the material in the crucible 4 was dissolved, and the melt 8 was stirred using a gold stirring jig. The CaMgZr-substituted GGG substrate 10 was attached to the gold fixture 2 and placed in the furnace. After the furnace temperature was lowered to 790 ° C., one side of the substrate 10 was brought into contact with the melt 8 and epitaxial growth was performed for 42 hours. A magnetic garnet single crystal film 12 having a thickness of 570 μm was obtained. The composition of the grown single crystal was analyzed by X-ray fluorescence analysis. As a result, the composition was Bi _0.93 Gd _1.67 Yb _0.20 Na _0.20 Fe _4.60 Ge _0.40 O ₁₂ . It was confirmed that this single crystal did not contain Pb. The grown single crystal film 12 was processed to produce a single crystal plate having a rotation angle of 45 deg with respect to light having a wavelength of 1.55 μm. A non-reflective coating was formed on the polished surface of the single crystal plate to form a Faraday rotator. When the optical characteristics of the manufactured rotor were evaluated by making light having a wavelength of 1.55 μm incident, the characteristics were satisfactory as a Faraday rotator.

（実施例１１）
白金製のルツボ４にＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、ＴｉＯ_２、ＳｉＯ_２、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。９５０℃まで炉温を上げてルツボ４内の材料を溶解し、金製の攪拌用冶具を使用して融液８を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板１０を金製の固定冶具２に取り付けて炉内に投入し、７４６℃まで炉温を下げてから基板１０の片面を融液８に接触させてエピタキシャル成長を３６時間行った。膜厚４８０μｍの磁性ガーネット単結晶膜１２が得られた。育成した単結晶を蛍光Ｘ線分析法により組成分析したところ、組成はＢｉ_１．２８Ｇｄ_１．２０Ｙｂ_０．５０Ｎａ_０．０２Ｆｅ_４．９６Ｔｉ_０．０１Ｓｉ_０．０１Ｐｔ_０．０２Ｏ_１２であった。この単結晶にＰｂは含有されていないことが確認された。育成した単結晶膜１２を加工して、波長１．５５μｍの光に対して回転角４５ｄｅｇとなる単結晶板を作製した。その単結晶板の研磨面に無反射コートを成膜してファラデー回転子とした。波長１．５５μｍの光を入射させて、作製した回転子の光学特性を評価したところ、ファラデー回転子として問題のない特性であった。 (Example 11)
A platinum crucible 4 was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , TiO ₂ , SiO ₂ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. The furnace temperature was raised to 950 ° C., the material in the crucible 4 was dissolved, and the melt 8 was stirred using a gold stirring jig. The CaMgZr-substituted GGG substrate 10 was attached to the gold fixture 2 and placed in the furnace. After the furnace temperature was lowered to 746 ° C., one side of the substrate 10 was brought into contact with the melt 8 and epitaxial growth was performed for 36 hours. A magnetic garnet single crystal film 12 having a thickness of 480 μm was obtained. The composition of the grown single crystal was analyzed by X-ray fluorescence analysis. As a result, the composition was Bi _1.28 Gd _1.20 Yb _0.50 Na _0.02 Fe _4.96 Ti _0.01 Si _0.01 Pt _0.02. It was O _12. It was confirmed that this single crystal did not contain Pb. The grown single crystal film 12 was processed to produce a single crystal plate having a rotation angle of 45 deg with respect to light having a wavelength of 1.55 μm. A non-reflective coating was formed on the polished surface of the single crystal plate to form a Faraday rotator. When the optical characteristics of the manufactured rotor were evaluated by making light having a wavelength of 1.55 μm incident, the characteristics were satisfactory as a Faraday rotator.

（実施例１２）
金製のルツボ４にＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨ、ＫＯＨを充填して、電気炉に配置した。９５０℃まで炉温を上げてルツボ４内の材料を溶解し、金製の攪拌用冶具を使用して融液８を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板１０を金製の固定冶具２に取り付けて炉内に投入し、７４５℃まで炉温を下げてから基板１０の片面を融液８に接触させてエピタキシャル成長を４０時間行った。膜厚５００μｍの磁性ガーネット単結晶膜１２が得られた。育成した単結晶を蛍光Ｘ線分析法により組成分析したところ、組成はＢｉ_１．３０Ｇｄ_１．２０Ｙｂ_０．５０Ｆｅ_５．００Ｏ_１２であり、Ｎａは検出できたが組成を確定することはできなかった。また、ＰｂとＫは検出されなかった。次にＩＣＰ分析法で詳しく組成を評価したところ、Ｎａの含有量を確定できた。その結果、磁性ガーネット単結晶の化学式は、（ＢｉＧｄＹｂ）_{２．９９８}Ｎａ_{０．００２}Ｆｅ_{５．０００}Ｏ_１２であることが分かった。従ってこの単結晶にＰｂは含有されていないことが確認された。育成した単結晶膜１２を加工して、波長１．５５μｍの光に対してファラデー回転角４５ｄｅｇとなる単結晶板を作製した。その単結晶板の研磨面に無反射コートを成膜してファラデー回転子とした。波長１．５５μｍの光を入射させて、作製した回転子の光学特性を評価したところ、ファラデー回転子として問題のない特性であった。 (Example 12)
A gold crucible 4 was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , B ₂ O ₃ , Bi ₂ O ₃ , NaOH, and KOH and placed in an electric furnace. The furnace temperature was raised to 950 ° C., the material in the crucible 4 was dissolved, and the melt 8 was stirred using a gold stirring jig. The CaMgZr-substituted GGG substrate 10 was attached to the gold fixture 2 and placed in the furnace. After the furnace temperature was lowered to 745 ° C., one side of the substrate 10 was brought into contact with the melt 8 and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film 12 having a thickness of 500 μm was obtained. Composition analysis of the grown single crystal by X-ray fluorescence analysis revealed that the composition was Bi _1.30 Gd _1.20 Yb _0.50 Fe _5.00 O ₁₂ and Na was detected but the composition was determined. I couldn't. Moreover, Pb and K were not detected. Next, when the composition was evaluated in detail by ICP analysis, the content of Na could be determined. As a result, it was found that the chemical formula of the magnetic garnet single crystal was (BiGdYb) _2.998 Na _0.002 Fe _5.000 O ₁₂ . Therefore, it was confirmed that this single crystal did not contain Pb. The grown single crystal film 12 was processed to produce a single crystal plate having a Faraday rotation angle of 45 deg with respect to light having a wavelength of 1.55 μm. A non-reflective coating was formed on the polished surface of the single crystal plate to form a Faraday rotator. When the optical characteristics of the manufactured rotor were evaluated by making light having a wavelength of 1.55 μm incident, the characteristics were satisfactory as a Faraday rotator.

本発明の実施の形態における磁性ガーネット単結晶に入り得る各元素の価数とイオン半径とを示す図である。It is a figure which shows the valence and ionic radius of each element which can enter in the magnetic garnet single crystal in embodiment of this invention. 本発明の実施の形態における磁性ガーネット単結晶の製造工程の一部を示す図である。It is a figure which shows a part of manufacturing process of the magnetic garnet single crystal in embodiment of this invention.

Explanation of symbols

２固定冶具
４ルツボ
８融液
１０基板
１２単結晶膜 2 Fixing jig 4 Crucible 8 Melt 10 Substrate 12 Single crystal film

Claims

Grown by liquid phase epitaxy,
Chemical formula Bi _x Na _y Pb _z M1 _3-xyz Fe _5-w M2 _w O ₁₂
(In the formula, M1 is at least one element selected from Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu, and M2 is Ga, Al, In, Ti, Ge, At least one element selected from Si and Pt, 0.5 <x ≦ 2.0, 0 <y ≦ 0.02 , 0 ≦ z <0.01, 0.19 ≦ 3-x− yz <2.5, 0 ≦ w ≦ 1.6)
A magnetic garnet single crystal characterized by the following:

An optical element formed of the magnetic garnet single crystal according to claim 1 .