JP4821344B2

JP4821344B2 - Magnetic garnet single crystal and optical element using the same

Info

Publication number: JP4821344B2
Application number: JP2006029339A
Authority: JP
Inventors: 敦大井戸
Original assignee: TDK Corp
Current assignee: TDK Corp
Priority date: 2006-02-07
Filing date: 2006-02-07
Publication date: 2011-11-24
Anticipated expiration: 2026-02-07
Also published as: JP2007210806A

Description

本発明は、磁性ガーネット単結晶及びそれを用いた光学素子に関する。 The present invention relates to a magnetic garnet single crystal and an optical element using the same.

ファラデー回転子は、透過する光の偏光面を回転させる機能を有する光学素子であり、通信用光アイソレータ、光アッテネータ、光サーキュレータ、光磁界センサ等の光デバイスに使用される。ファラデー回転子は、一般に板状のビスマス（Ｂｉ）置換希土類鉄ガーネット単結晶を用いて作製される。Ｂｉ置換希土類鉄ガーネット単結晶は、フラックス法の一種である液相エピタキシャル（ＬＰＥ）法により育成される。 The Faraday rotator is an optical element having a function of rotating a polarization plane of transmitted light, and is used for an optical device such as a communication optical isolator, an optical attenuator, an optical circulator, and an optical magnetic field sensor. A Faraday rotator is generally manufactured using a plate-like bismuth (Bi) -substituted rare earth iron garnet single crystal. Bi-substituted rare earth iron garnet single crystal is grown by a liquid phase epitaxial (LPE) method which is a kind of flux method.

ＬＰＥ法によりＢｉ置換希土類鉄ガーネット単結晶を育成する際には、過飽和状態を保ちながらガーネット単結晶を安定に成長させるために、一般に酸化鉛（ＰｂＯ）、酸化ビスマス（Ｂｉ_２Ｏ_３）及び酸化ホウ素（Ｂ_２Ｏ_３）が溶媒として用いられる。このため磁性ガーネット単結晶の育成時には結晶中に少量の鉛（Ｐｂ）が混入する。従来、通信用光デバイスに使用されるファラデー回転子には、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が用いられている。
特開２００１−０４４０２６号公報特開２００１−０４４０２７号公報特公平６−０４６６０４号公報 When growing Bi-substituted rare earth iron garnet single crystals by the LPE method, lead oxide (PbO), bismuth oxide (Bi ₂ O ₃ ) and oxidation are generally used to stably grow the garnet single crystal while maintaining a supersaturated state. Boron (B ₂ O ₃ ) is used as a solvent. For this reason, when growing a magnetic garnet single crystal, a small amount of lead (Pb) is mixed in the crystal. Conventionally, the Faraday rotator to be used for communication optical device, in the chemical formula _{_{_{_{Bi 3-x-y M1 x}}}} Pb y Fe 5-z-w M2 z M3 w O 12 quantity y of Pb is 0.03 to 0 A magnetic garnet single crystal of about .06 is used.
JP 2001-044026 A JP 2001-044027 A Japanese Examined Patent Publication No. 6-046604

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Ｐｂの含有量を削減す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Ｐｂ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されるＰｂの量を削減又は除去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 Pb, 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 Pb mixed therein has become a problem because it can cause environmental pollution. Therefore, it is necessary to reduce or remove the amount of Pb contained in the magnetic garnet single crystal that is a material constituting the Faraday rotator.

本発明の目的は、Ｐｂ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 a reduced Pb content and an optical element using the same.

上記目的は、化学式Ｂｉ_αＮａ_βＭ１_{３−α−β}Ｆｅ_{５−γ−δ−ε}Ｍ２_γＭ３_δＭ４_εＯ_１２（Ｍ１はＹ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、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Ｓｎ、Ｒｈ、Ｒｕ、Ｈｆ、Ｚｒから選択される少なくとも１種類以上の元素、Ｍ３はＶ、Ｓｂ、Ｎｂ、Ｔａから選択される少なくとも１種類以上の元素、Ｍ４はＷ、Ｍｏ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≦α≦２．０、０＜β≦２．４、０＜３−α−β＜２．５、０＜γ＋δ＋ε≦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。 The purpose is to use the chemical formula Bi _α Na _β M1 _3-α-β Fe _5-γ-δ-ε M2 _γ M3 _δ M4 _ε O ₁₂ (M1 is Y, La, Ce, Pr, Nd, Sm, Eu, Gd, At least one element selected from Tb, Dy, Ho, Er, Tm, Yb, Lu, M2 is at least one element selected from Sn, Rh, Ru, Hf, Zr, M3 is V, At least one element selected from Sb, Nb, Ta, M4 is at least one element selected from W, Mo, 0.5 ≦ α ≦ 2.0, 0 <β ≦ 2. 4, 0 <3-α−β <2.5, 0 <γ + δ + ε ≦ 1.6). This is achieved by a magnetic garnet single crystal.

上記本発明の磁性ガーネット単結晶であって、前記γ、δ及びεは、γ＋２δ＋３ε≧０．００７の関係を満たすことを特徴とする。 In the magnetic garnet single crystal of the present invention, the γ, δ, and ε satisfy a relationship of γ + 2δ + 3ε ≧ 0.007.

また上記目的は、上記本発明の磁性ガーネット単結晶を用いて作製されていることを特徴とする光学素子によって達成される。 The above-mentioned object is achieved by an optical element characterized by being produced using the magnetic garnet single crystal of the present invention.

本発明によれば、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 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について図１を用いて説明する。本実施の形態では、従来の溶媒に含まれるＰｂの少なくとも一部をナトリウム（Ｎａ）で代替し、Ｎａを含む溶液から磁性ガーネット単結晶を育成する。Ｎａと酸素とを含有する物質は他の酸化物に比べて低い温度で溶解するものが多いため、Ｎａは磁性ガーネット単結晶を育成する際の溶媒として有効である。例えば水酸化ナトリウム（ＮａＯＨ）を含む溶媒から育成され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を有する。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を溶媒に用いることにより、従来磁性ガーネット単結晶に微量含まれていたＰｂをほぼ完全に除去できる。 A magnetic garnet single crystal and an optical element using the same according to an embodiment of the present invention will be described with reference to FIG. In this embodiment, at least a part of Pb contained in a conventional solvent is replaced with sodium (Na), and a magnetic garnet single crystal is grown from a solution containing Na. Since many substances containing Na and oxygen dissolve at a lower temperature than other oxides, Na is effective as a solvent for growing magnetic garnet single crystals. For example, a magnetic garnet single crystal grown from a solvent containing sodium hydroxide (NaOH) has excellent quality free from defects and cracks. By excluding PbO from the solvent material and using a substance containing Na and Bi ₂ O ₃ and B ₂ O ₃ as the solvent, Pb that has been conventionally contained in a trace amount in the magnetic garnet single crystal can be almost completely removed.

ところが、Ｎａを含む溶媒から育成したガーネット単結晶は、光通信で使用される１３００〜１６００ｎｍの波長帯域での光吸収が極めて大きいということが判明した。大きな光吸収を持つガーネット単結晶を加工してファラデー回転子等の光学素子を作製すると、光学素子の光損失（挿入損失）が高くなってしまうという問題が生じ得る。したがって、Ｐｂがほぼ完全に除去された光学素子の光損失を低減させるために、Ｎａを含む溶媒を用いて育成されるガーネット単結晶の光吸収を減少させる必要がある。 However, it has been found that a garnet single crystal grown from a solvent containing Na has extremely large light absorption in a wavelength band of 1300 to 1600 nm used in optical communication. When an optical element such as a Faraday rotator is manufactured by processing a garnet single crystal having a large light absorption, there may be a problem that the optical loss (insertion loss) of the optical element increases. Therefore, in order to reduce the optical loss of the optical element from which Pb is almost completely removed, it is necessary to reduce the light absorption of the garnet single crystal grown using the solvent containing Na.

ここで、ＮａＯＨ、Ｂｉ_２Ｏ_３及びＢ_２Ｏ_３を溶媒としてＬＰＥ法により育成した磁性ガーネット単結晶（（ＢｉＧｄＹｂ）_３Ｆｅ_５Ｏ_１２）を加工して、ファラデー回転子を作製した。このファラデー回転子の波長１．５５μｍの光に対する光損失は３ｄＢであった。また、Ｐｂを含む溶媒からＬＰＥ法により育成した磁性ガーネット単結晶（（ＢｉＧｄＹｂ）_３Ｆｅ_５Ｏ_１２）を加工して、別のファラデー回転子を作製した。このファラデー回転子の波長１．５５μｍの光に対する光損失は０．０５ｄＢ以下であった。したがって、Ｎａを含む溶媒を用いて作製されたファラデー回転子の光損失は、Ｐｂを含む溶媒を用いて作製されたファラデー回転子の光損失と比較して極めて高いことが分かった。Ｎａを含む溶媒から育成した磁性ガーネット単結晶の組成を蛍光Ｘ線分析により調べたところ、１００〜３００ｐｐｍ程度のＮａが検出された。Ｂｉ置換希土類鉄ガーネットを構成するカチオン（陽イオン）は、基本的に３価である。このため、１価が安定な価数であるＮａのカチオンが磁性ガーネット単結晶中に入ると、電荷のバランスが崩れて磁性ガーネット単結晶が半導体となる。これにより、Ｎａを含む磁性ガーネット単結晶では光吸収が発生していると考えられる。 Here, a magnetic garnet single crystal ((BiGdYb) ₃ Fe ₅ O ₁₂ ) grown by the LPE method using NaOH, Bi ₂ O ₃ and B ₂ O ₃ as a solvent was processed to produce a Faraday rotator. The optical loss of this Faraday rotator with respect to light having a wavelength of 1.55 μm was 3 dB. Further, another Faraday rotator was produced by processing a magnetic garnet single crystal ((BiGdYb) ₃ Fe ₅ O ₁₂ ) grown from a solvent containing Pb by the LPE method. The optical loss of this Faraday rotator with respect to light having a wavelength of 1.55 μm was 0.05 dB or less. Therefore, it was found that the optical loss of the Faraday rotator manufactured using the solvent containing Na is extremely higher than the optical loss of the Faraday rotator manufactured using the solvent containing Pb. When the composition of the magnetic garnet single crystal grown from the solvent containing Na was examined by fluorescent X-ray analysis, about 100 to 300 ppm of Na was detected. The cation (cation) constituting the Bi-substituted rare earth iron garnet is basically trivalent. For this reason, when a cation of Na, which is a monovalent valence, enters the magnetic garnet single crystal, the charge balance is lost and the magnetic garnet single crystal becomes a semiconductor. Thereby, it is considered that light absorption occurs in the magnetic garnet single crystal containing Na.

本実施の形態では、酸化スズ（ＳｎＯ_２）、酸化ロジウム（ＲｈＯ_２）、酸化ルテニウム（ＲｕＯ_２）、酸化ハフニウム（ＨｆＯ_２）、酸化ジルコニウム（ＺｒＯ_２）、酸化バナジウム（Ｖ_２Ｏ_５）、酸化アンチモン（Ｓｂ_２Ｏ_５）、酸化ニオブ（Ｎｂ_２Ｏ_５）、酸化タンタル（Ｔａ_２Ｏ_５）、酸化モリブデン（ＭｏＯ_３）、及び酸化タングステン（ＷＯ_３）のうち少なくとも１種をＮａと共に配合材料に加え、磁性ガーネット単結晶を育成した。育成した磁性ガーネット単結晶をファラデー回転子に加工して光損失を評価したところ、光損失が低下する傾向が認められた。Ｓｎ、Ｒｈ、Ｒｕ、Ｈｆ及びＺｒはガーネット中で４価のカチオンが安定となり、Ｖ、Ｓｂ、Ｎｂ及びＴａはガーネット中で５価のカチオンが安定となり、Ｍｏ及びＷはガーネット中で６価のカチオンが安定となる。Ｎａのカチオンと共に磁性ガーネット単結晶中に入るこれらの４価、５価又は６価のカチオンが電荷を補償することにより電荷のバランスがとれ、磁性ガーネット単結晶は絶縁体となる。これにより、磁性ガーネット単結晶の光吸収が減少したと考えられる。 In this embodiment mode, tin oxide (SnO ₂ ), rhodium oxide (RhO ₂ ), ruthenium oxide (RuO ₂ ), hafnium oxide (HfO ₂ ), zirconium oxide (ZrO ₂ ), vanadium oxide (V ₂ O ₅ ), At least one of antimony oxide (Sb ₂ O ₅ ), niobium oxide (Nb ₂ O ₅ ), tantalum oxide (Ta ₂ O ₅ ), molybdenum oxide (MoO ₃ ), and tungsten oxide (WO ₃ ) is blended with Na In addition to the materials, magnetic garnet single crystals were grown. When the grown magnetic garnet single crystal was processed into a Faraday rotator and the optical loss was evaluated, a tendency for the optical loss to decrease was observed. Sn, Rh, Ru, Hf and Zr are stable in tetravalent cations in garnet, V, Sb, Nb and Ta are stable in pentavalent cations in garnet, and Mo and W are hexavalent in garnet. Cations become stable. These tetravalent, pentavalent, or hexavalent cations that enter the magnetic garnet single crystal together with the Na cation compensate for the charge to balance the charge, and the magnetic garnet single crystal becomes an insulator. Thereby, it is considered that the light absorption of the magnetic garnet single crystal is reduced.

さらに本実施の形態では、Ｎａを含む配合材料にＳｎＯ_２を種々の配合量で加えて、複数種類の磁性ガーネット単結晶を育成した。本実施の形態では、配合材料中におけるＳｎのＦｅに対するモル比（Ｓｎ／Ｆｅモル比）をパラメータとして用い、ＳｎＯ_２の配合量を変えることによりＳｎ／Ｆｅモル比を０〜０．０２の範囲内で種々の値に設定した。育成した複数種類の磁性ガーネット単結晶をそれぞれファラデー回転子に加工し、光損失を評価した。その結果、配合材料にＳｎＯ_２をわずかに添加するだけでもファラデー回転子の光損失は大幅に低下し、Ｓｎ／Ｆｅモル比が０．００４である配合材料を用いて作製したファラデー回転子の光損失は、０〜０．０１ｄＢと極めて低くなることが分かった。Ｓｎ／Ｆｅモル比を０．００４より大きくしても、ファラデー回転子の光損失は０〜０．０１ｄＢで変化はなかった。 Further, in this embodiment, in addition to SnO ₂ in various amounts to the formulation material containing Na, it was grown several kinds of magnetic garnet single crystal. In the present embodiment, the molar ratio of Sn to Fe (Sn / Fe molar ratio) in the compounding material is used as a parameter, and the Sn / Fe molar ratio is in the range of 0 to 0.02 by changing the compounding amount of SnO _2. Various values were set. Multiple kinds of grown magnetic garnet single crystals were processed into Faraday rotators, and the optical loss was evaluated. As a result, the light loss of the Faraday rotator is significantly reduced even if a slight amount of SnO ₂ is added to the compounding material, and the light of the Faraday rotator produced using the compounding material having a Sn / Fe molar ratio of 0.004. The loss was found to be very low, 0-0.01 dB. Even when the Sn / Fe molar ratio was larger than 0.004, the optical loss of the Faraday rotator was 0 to 0.01 dB, and there was no change.

Ｓｎ／Ｆｅモル比が０．００４である配合材料から育成した磁性ガーネット単結晶を蛍光Ｘ線分析及びＩＣＰ（ＩｎｄｕｃｔｉｖｅｌｙＣｏｕｐｌｅｄＰｌａｓｍａ；高周波誘導結合プラズマ）分析により組成分析したところ、化学式（ＢｉＧｄＹｂ）_{２．９９６}Ｎａ_{０．００４}Ｆｅ_{４．９９３}Ｓｎ_{０．００７}Ｏ_１２が得られた。組成分析の結果、Ｓｎのようにガーネット中で４価が安定な元素が磁性ガーネット単結晶中に入ることによってファラデー回転子の光損失が低下し、特に、磁性ガーネット単結晶中のＳｎ量γを化学式で０．００７にすると（γ＝０．００７）、ファラデー回転子の光損失を最低にすることができることが分かった。また、磁性ガーネット単結晶中のＳｎ量γがさらに増加しても（γ＞０．００７）、ファラデー回転子の光損失は最低値のままであることが分かった。 A magnetic garnet single crystal grown from a compounding material having a Sn / Fe molar ratio of 0.004 was subjected to compositional analysis by fluorescent X-ray analysis and ICP (Inductively Coupled Plasma) analysis _. Chemical formula (BiGdYb) ₉₉₆ Na _0.004 Fe _4.993 Sn _0.007 O ₁₂ was obtained. As a result of the compositional analysis, the light loss of the Faraday rotator is reduced when a tetravalent element such as Sn enters the magnetic garnet single crystal, and in particular, the Sn amount γ in the magnetic garnet single crystal is reduced. It was found that when the chemical formula is 0.007 (γ = 0.007), the optical loss of the Faraday rotator can be minimized. It was also found that the optical loss of the Faraday rotator remained at the lowest value even when the Sn content γ in the magnetic garnet single crystal was further increased (γ> 0.007).

Ｓｎと同様にガーネット中で４価が安定なＲｈ、Ｒｕ、Ｈｆ及びＺｒ等をＳｎに代えて用いても、ファラデー回転子の光損失を低減できることが分かった。特に、磁性ガーネット単結晶中でのこれらの元素の量γを化学式で０．００７又はそれ以上にすると（γ≧０．００７）、ファラデー回転子の光損失を最低にすることができた。 It has been found that the optical loss of the Faraday rotator can be reduced even if Rh, Ru, Hf, Zr, etc., which are stable in tetravalence in the garnet, are used instead of Sn as in the case of Sn. In particular, when the amount γ of these elements in the magnetic garnet single crystal was set to 0.007 or more in the chemical formula (γ ≧ 0.007), the optical loss of the Faraday rotator could be minimized.

また、ガーネット中で５価が安定なＶ、Ｓｂ、Ｎｂ及びＴａ等、又はガーネット中で６価が安定なＷ及びＭｏ等を用いても、同様にファラデー回転子の光損失を低減できることが分かった。ただし、ガーネット中で５価又は６価が安定なこれらの元素を用いた場合、ファラデー回転子の光損失が最低となるための条件は上記と異なっていた。ガーネット中で５価のカチオンとなるＶ、Ｓｂ、Ｎｂ及びＴａについては、磁性ガーネット単結晶中でのこれらの元素の量δを化学式で０．００３５又はそれ以上にすると（２δ≧０．００７）、ファラデー回転子の光損失を最低にすることができた。ガーネット中で６価のカチオンとなるＷ及びＭｏについては、磁性ガーネット単結晶中でのこれらの元素の量εを化学式で０．００２３又はそれ以上にすると（３ε≧０．００７）、ファラデー回転子の光損失を最低にすることができた。 Also, it can be seen that the optical loss of the Faraday rotator can be similarly reduced by using V, Sb, Nb, Ta, etc., which are stable in pentavalent in garnet, or W, Mo, etc., which are stable in hexavalent in garnet. It was. However, when these elements, which are stable in pentavalent or hexavalent form, are used in the garnet, the conditions for minimizing the optical loss of the Faraday rotator were different from the above. For V, Sb, Nb, and Ta that are pentavalent cations in garnet, if the amount δ of these elements in the magnetic garnet single crystal is 0.0035 or more in the chemical formula (2δ ≧ 0.007) The optical loss of the Faraday rotator could be minimized. For W and Mo, which are hexavalent cations in garnet, when the amount ε of these elements in the magnetic garnet single crystal is 0.0023 or more in the chemical formula (3ε ≧ 0.007), the Faraday rotator Was able to minimize the light loss.

さらに、Ｓｎ、Ｒｈ、Ｒｕ、Ｈｆ、Ｚｒ、Ｖ、Ｓｂ、Ｎｂ、Ｔａ、Ｗ及びＭｏのうち２種以上を組み合わせて用いても、同様にファラデー回転子の光損失を低減できることが分かった。すなわち、磁性ガーネット単結晶の組成を示す化学式において、Ｓｎ、Ｒｈ、Ｒｕ、Ｈｆ及びＺｒから選択される少なくとも１種の元素の量γ、Ｖ、Ｓｂ、Ｎｂ及びＴａから選択される少なくとも１種の元素の量δ、並びにＷ及びＭｏから選択される少なくとも１種の元素の量εがγ＋δ＋ε＞０の関係を満たすことによって、磁性ガーネット単結晶の光吸収及びファラデー回転子の光損失が低減する。また、γ、δ及びεがγ＋２δ＋３ε≧０．００７の関係を満たすことによって、磁性ガーネット単結晶の光吸収及びファラデー回転子の光損失はさらに低減する。 Furthermore, it has been found that even when two or more of Sn, Rh, Ru, Hf, Zr, V, Sb, Nb, Ta, W and Mo are used in combination, the optical loss of the Faraday rotator can be reduced. That is, in the chemical formula showing the composition of the magnetic garnet single crystal, the amount of at least one element selected from Sn, Rh, Ru, Hf and Zr γ, at least one selected from V, Sb, Nb and Ta When the element amount δ and the amount ε of at least one element selected from W and Mo satisfy the relationship γ + δ + ε> 0, the light absorption of the magnetic garnet single crystal and the light loss of the Faraday rotator are reduced. Moreover, when γ, δ, and ε satisfy the relationship of γ + 2δ + 3ε ≧ 0.007, the light absorption of the magnetic garnet single crystal and the light loss of the Faraday rotator are further reduced.

Ｓｎ、Ｒｈ、Ｒｕ、Ｈｆ、Ｚｒ、Ｖ、Ｓｂ、Ｎｂ、Ｔａ、Ｗ及びＭｏが所定量以上ガーネット単結晶中に入り電荷のバランスが崩れると、電荷を補償するようにＮａがガーネット中に入る。そのためＳｎ、Ｒｈ、Ｒｕ、Ｈｆ、Ｚｒ、Ｖ、Ｓｂ、Ｎｂ、Ｔａ、Ｗ及びＭｏでＦｅを多量に置換した場合でも、Ｎａがガーネット単結晶に入ることにより電荷は補償される。しかしながら、磁性ガーネット単結晶においてＳｎ、Ｒｈ、Ｒｕ、Ｈｆ、Ｚｒ、Ｖ、Ｓｂ、Ｎｂ、Ｔａ、Ｗ及びＭｏの置換量が１．６より大きくなると、キュリー点が室温付近まで低下するためファラデー回転子としての使用が困難になる。したがって、Ｓｎ、Ｒｈ、Ｒｕ、Ｈｆ、Ｚｒ、Ｖ、Ｓｂ、Ｎｂ、Ｔａ、Ｗ及びＭｏの置換量の上限は化学式で１．６となる（γ＋δ＋ε≦１．６）。 When Sn, Rh, Ru, Hf, Zr, V, Sb, Nb, Ta, W, and Mo enter the garnet single crystal for a predetermined amount or more and the charge balance is lost, Na enters the garnet so as to compensate the charge. . Therefore, even when a large amount of Fe is substituted with Sn, Rh, Ru, Hf, Zr, V, Sb, Nb, Ta, W, and Mo, the charge is compensated by Na entering the garnet single crystal. However, in the magnetic garnet single crystal, when the substitution amount of Sn, Rh, Ru, Hf, Zr, V, Sb, Nb, Ta, W, and Mo becomes larger than 1.6, the Curie point decreases to near room temperature, so Faraday rotation Use as a child becomes difficult. Therefore, the upper limit of the substitution amount of Sn, Rh, Ru, Hf, Zr, V, Sb, Nb, Ta, W and Mo is 1.6 in the chemical formula (γ + δ + ε ≦ 1.6).

４価が安定な元素と１価が安定な元素とが２：１の比率でガーネット単結晶に入れば電荷のバランスをとることができるため、４価が安定なＳｎ、Ｒｈ、Ｒｕ、Ｈｆ及びＺｒが化学式で１．６だけガーネット単結晶に入るとき、Ｎａは化学式で０．８だけ入る。また、５価が安定な元素と１価が安定な元素とが１：１の比率でガーネット単結晶に入れば電荷のバランスをとることができるため、５価が安定なＶ、Ｓｂ、Ｎｂ及びＴａが化学式で１．６だけガーネット単結晶に入るとき、Ｎａは化学式で１．６だけ入る。さらに、６価が安定な元素と１価が安定な元素とが２：３の比率でガーネット単結晶に入れば電荷のバランスをとることができるため、６価が安定なＷ及びＭｏが化学式で１．６だけガーネット単結晶に入るとき、Ｎａは化学式で２．４だけ入る。すなわち、ファラデー回転子に使用可能な磁性ガーネット単結晶に含まれるＮａの上限は化学式で２．４となる（β≦２．４）。 Since the charge balance can be achieved if the tetravalent stable element and the monovalent stable element enter the garnet single crystal at a ratio of 2: 1, the tetravalent stable Sn, Rh, Ru, Hf and When Zr enters the garnet single crystal by the chemical formula by 1.6, Na enters by 0.8 by the chemical formula. Further, since the charge can be balanced if the element having stable pentavalent and the element having stable monovalent enters the garnet single crystal at a ratio of 1: 1, V, Sb, Nb and When Ta enters the garnet single crystal by a chemical formula of 1.6, Na enters by a chemical formula of 1.6. Furthermore, since the balance of charge can be achieved if an element with stable hexavalence and an element with stable monovalence enter the garnet single crystal at a ratio of 2: 3, W and Mo with stable hexavalence are expressed by chemical formulas. When entering a garnet single crystal by 1.6, Na enters only 2.4 by chemical formula. That is, the upper limit of Na contained in the magnetic garnet single crystal usable for the Faraday rotator is 2.4 in the chemical formula (β ≦ 2.4).

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（α≦２．０）。一方、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、ガーネット単結晶中のＢｉは化学式で０．５以上必要である（α≧０．５）。 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 stably enter the garnet single crystal up to about 2.0 in the chemical formula (α ≦ 2.0). On the other hand, in order to obtain a sufficient rotation coefficient (deg / μm) as a Faraday rotator, Bi in the garnet single crystal must be 0.5 or more in the chemical formula (α ≧ 0.5).

また本実施の形態では、磁性ガーネット単結晶に含まれる希土類元素として、単独又は組合せにより安定してＦｅとガーネット単結晶を作ることができるイットリウム（Ｙ）、ランタン（Ｌａ）、セリウム（Ｃｅ）、プラセオジム（Ｐｒ）、ネオジム（Ｎｄ）、サマリウム（Ｓｍ）、ユウロピウム（Ｅｕ）、ガドリニウム（Ｇｄ）、テルビウム（Ｔｂ）、ジスプロシウム（Ｄｙ）、ホルミウム（Ｈｏ）、エルビウム（Ｅｒ）、ツリウム（Ｔｍ）、イッテルビウム（Ｙｂ）及びルテチウム（Ｌｕ）が用いられる。 In the present embodiment, as the rare earth element contained in the magnetic garnet single crystal, yttrium (Y), lanthanum (La), cerium (Ce), which can stably form Fe and garnet single crystals alone or in combination, Praseodymium (Pr), neodymium (Nd), samarium (Sm), europium (Eu), gadolinium (Gd), terbium (Tb), dysprosium (Dy), holmium (Ho), erbium (Er), thulium (Tm), Ytterbium (Yb) and lutetium (Lu) are used.

以上説明したように、本実施の形態による磁性ガーネット単結晶は、化学式Ｂｉ_αＮａ_βＭ１_{３−α−β}Ｆｅ_{５−γ−δ−ε}Ｍ２_γＭ３_δＭ４_εＯ_１２（Ｍ１はＹ、Ｌａ、Ｃｅ、Ｐｒ、Ｎｄ、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Ｓｎ、Ｒｈ、Ｒｕ、Ｈｆ、Ｚｒから選択される少なくとも１種類以上の元素、Ｍ３はＶ、Ｓｂ、Ｎｂ、Ｔａから選択される少なくとも１種類以上の元素、Ｍ４はＷ、Ｍｏ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≦α≦２．０、０＜β≦２．４、０＜３−α−β＜２．５、０＜γ＋δ＋ε≦１．６）で表される。本実施の形態によれば、Ｐｂをほぼ完全に除去した磁性ガーネット単結晶及びそれを用いた光学素子を実現できる。また本実施の形態によれば、磁性ガーネット単結晶の光吸収及び光学素子の光損失を低減できる。
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について、実施例及び比較例を用いてより具体的に説明する。 As described above, the magnetic garnet single crystal according to this embodiment, the chemical formula _{_{_{Bi α Na β M1 3-α}}} -β Fe 5-γ-δ-ε M2 γ M3 δ M4 ε O 12 (M1 is Y, La , Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, M2 is selected from Sn, Rh, Ru, Hf, Zr At least one element selected from the group consisting of at least one element selected from V, Sb, Nb and Ta, M4 is at least one element selected from W and Mo, 0.5 ≦ α ≦ 2.0, 0 <β ≦ 2.4, 0 <3-α−β <2.5, 0 <γ + δ + ε ≦ 1.6). According to the present embodiment, a magnetic garnet single crystal from which Pb is almost completely removed and an optical element using the same can be realized. Moreover, according to this Embodiment, the optical absorption of a magnetic garnet single crystal and the optical loss of an optical element can be reduced.
Hereinafter, the magnetic garnet single crystal and the optical element using the same according to the present embodiment will be described more specifically with reference to Examples and Comparative Examples.

（実施例１）
金（Ａｕ）製のルツボにＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、ＳｎＯ_２、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。このときのＳｎ／Ｆｅモル比を０．００６とした。９５０℃まで炉温を上げてルツボ内の材料を溶解して融液（溶液）を生成し、Ａｕ製の攪拌用冶具を使用して融液を攪拌した。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エハを用いる。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）を用いている。 Example 1
A crucible made of gold (Au) was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , SnO ₂ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. At this time, the Sn / Fe molar ratio was set to 0.006. The furnace temperature was raised to 950 ° C. to dissolve the material in the crucible to produce a melt (solution), and the melt was stirred using a stirring jig made of Au. 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 ) is used as the single crystal growth substrate.

ＣａＭｇＺｒ置換ＧＧＧ基板をＡｕ製の固定冶具に取り付けて炉内に投入し、８５０℃まで炉温を下げてから基板の片面を融液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が得られた。育成した単結晶膜を蛍光Ｘ線分析により組成分析したところ、組成はＢｉ_{１．３００}Ｇｄ_{１．２００}Ｙｂ_{０．５００}Ｆｅ_{４．９９０}Ｓｎ_{０．０１０}Ｏ_１２であり、Ｎａは検出できなかった。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膜の化学式は（ＢｉＧｄＹｂ）_{２．９９５}Ｎａ_{０．００５}（ＦｅＳｎ）_{５．０００}Ｏ_１２であることが分かった。育成した単結晶膜を加工して、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、ファラデー回転子を作製した。作製したファラデー回転子から２０個抜き取り、波長１．５５μｍの光に対する光損失を評価した。ファラデー回転子の光損失は０〜０．０１ｄＢであり、極めて低損失であった。 The CaMgZr-substituted GGG substrate was attached to a fixed fixture made of Au and placed in a furnace. After the furnace temperature was lowered to 850 ° C., one side of the substrate was brought into contact with the melt and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film having a thickness of 500 μm was obtained. The grown single crystal film was compositionally analyzed by X-ray fluorescence analysis, the composition is a _{_{_{_{Bi 1.300 Gd 1.200 Yb 0.500 Fe 4.990}}}} Sn 0.010 O 12, Na could be detected. 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 film was found to be _{_{_{_{5.000 O 12 (BiGdYb) 2.995 Na}}}} 0.005 (FeSn). The grown single crystal film 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 produce a Faraday rotator. Twenty pieces were extracted from the prepared Faraday rotator and evaluated for light loss with respect to light having a wavelength of 1.55 μm. The optical loss of the Faraday rotator was 0 to 0.01 dB, which was extremely low loss.

（実施例２）
Ａｕ製のルツボにＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、ＳｎＯ_２、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。このときのＳｎ／Ｆｅモル比を０．００４とした。９５０℃まで炉温を上げてルツボ内の材料を溶解して融液を生成し、Ａｕ製の攪拌用冶具を使用して融液を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板をＡｕ製の固定冶具に取り付けて炉内に投入し、８５０℃まで炉温を下げてから基板の片面を融液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が得られた。育成した単結晶膜を蛍光Ｘ線分析により組成分析したところ、組成はＢｉ_{１．３００}Ｇｄ_{１．２００}Ｙｂ_{０．５００}Ｆｅ_{４．９９３}Ｓｎ_{０．００７}Ｏ_１２であり、Ｎａは検出できなかった。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膜の化学式は（ＢｉＧｄＹｂ）_{２．９９６}Ｎａ_{０．００４}（ＦｅＳｎ）_{５．０００}Ｏ_１２であることが分かった。育成した単結晶膜を加工して、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、ファラデー回転子を作製した。作製したファラデー回転子から２０個抜き取り、波長１．５５μｍの光に対する光損失を評価した。ファラデー回転子の光損失は０〜０．０１ｄＢであり、極めて低損失であった。 (Example 2)
A crucible made of Au was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , SnO ₂ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. At this time, the Sn / Fe molar ratio was set to 0.004. The furnace temperature was raised to 950 ° C. to dissolve the material in the crucible to produce a melt, and the melt was stirred using a stirring jig made of Au. The CaMgZr-substituted GGG substrate was attached to a fixed fixture made of Au and placed in a furnace. After the furnace temperature was lowered to 850 ° C., one side of the substrate was brought into contact with the melt and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film having a thickness of 500 μm was obtained. The grown single crystal film was compositionally analyzed by X-ray fluorescence analysis, the composition is a _{_{_{_{Bi 1.300 Gd 1.200 Yb 0.500 Fe 4.993}}}} Sn 0.007 O 12, Na could be 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 film was (BiGdYb) _2.996 Na _0.004 (FeSn) _5.000 O ₁₂ . The grown single crystal film 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 produce a Faraday rotator. Twenty pieces were extracted from the prepared Faraday rotator and evaluated for light loss with respect to light having a wavelength of 1.55 μm. The optical loss of the Faraday rotator was 0 to 0.01 dB, which was extremely low loss.

（実施例３）
Ａｕ製のルツボにＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、ＳｎＯ_２、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。このときのＳｎ／Ｆｅモル比を０．００８とした。９５０℃まで炉温を上げてルツボ内の材料を溶解して融液を生成し、Ａｕ製の攪拌用冶具を使用して融液を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板をＡｕ製の固定冶具に取り付けて炉内に投入し、８５０℃まで炉温を下げてから基板の片面を融液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が得られた。育成した単結晶膜を蛍光Ｘ線分析により組成分析したところＮａが検出され、組成はＢｉ_{１．２９３}Ｇｄ_{１．２００}Ｙｂ_{０．５００}Ｎａ_{０．００７}Ｆｅ_{４．９８７}Ｓｎ_{０．０１３}Ｏ_１２であった。育成した単結晶膜を加工して、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、ファラデー回転子を作製した。作製したファラデー回転子から２０個抜き取り、波長１．５５μｍの光に対する光損失を評価した。ファラデー回転子の光損失は０〜０．０１ｄＢであり、極めて低損失であった。 (Example 3)
A crucible made of Au was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , SnO ₂ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. At this time, the Sn / Fe molar ratio was set to 0.008. The furnace temperature was raised to 950 ° C. to dissolve the material in the crucible to produce a melt, and the melt was stirred using a stirring jig made of Au. The CaMgZr-substituted GGG substrate was attached to a fixed fixture made of Au and placed in a furnace. After the furnace temperature was lowered to 850 ° C., one side of the substrate was brought into contact with the melt and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film having a thickness of 500 μm was obtained. When the grown single crystal film was compositionally analyzed by fluorescent X-ray analysis, Na was detected and the composition was Bi _1.293 Gd _1.200 Yb _0.500 Na _0.007 Fe _4.987 Sn _0.013 O _12. It was. The grown single crystal film 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 produce a Faraday rotator. Twenty pieces were extracted from the prepared Faraday rotator and evaluated for light loss with respect to light having a wavelength of 1.55 μm. The optical loss of the Faraday rotator was 0 to 0.01 dB, which was extremely low loss.

（実施例４）
Ａｕ製のルツボにＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、ＳｎＯ_２、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。このときのＳｎ／Ｆｅモル比を０．０１２とした。９５０℃まで炉温を上げてルツボ内の材料を溶解して融液を生成し、Ａｕ製の攪拌用冶具を使用して融液を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板をＡｕ製の固定冶具に取り付けて炉内に投入し、８５０℃まで炉温を下げてから基板の片面を融液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が得られた。育成した単結晶膜を蛍光Ｘ線分析により組成分析したところＮａが検出され、組成はＢｉ_{１．２９０}Ｇｄ_{１．２００}Ｙｂ_{０．５００}Ｎａ_{０．０１０}Ｆｅ_{４．９８０}Ｓｎ_{０．０２０}Ｏ_１２であった。育成した単結晶膜を加工して、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、ファラデー回転子を作製した。作製したファラデー回転子から２０個抜き取り、波長１．５５μｍの光に対する光損失を評価した。ファラデー回転子の光損失は０〜０．０１ｄＢであり、極めて低損失であった。 Example 4
A crucible made of Au was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , SnO ₂ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. At this time, the Sn / Fe molar ratio was set to 0.012. The furnace temperature was raised to 950 ° C. to dissolve the material in the crucible to produce a melt, and the melt was stirred using a stirring jig made of Au. The CaMgZr-substituted GGG substrate was attached to a fixed fixture made of Au and placed in a furnace. After the furnace temperature was lowered to 850 ° C., one side of the substrate was brought into contact with the melt and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film having a thickness of 500 μm was obtained. When the grown single crystal film was compositionally analyzed by fluorescent X-ray analysis, Na was detected and the composition was _Bi1.290 Gd _1.200 Yb _0.500 Na _0.010 Fe _4.980 Sn _0.020 O _12. It was. The grown single crystal film 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 produce a Faraday rotator. Twenty pieces were extracted from the prepared Faraday rotator and evaluated for light loss with respect to light having a wavelength of 1.55 μm. The optical loss of the Faraday rotator was 0 to 0.01 dB, which was extremely low loss.

（実施例５）
Ａｕ製のルツボにＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、ＳｎＯ_２、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。このときのＳｎ／Ｆｅモル比を０．０２０とした。９５０℃まで炉温を上げてルツボ内の材料を溶解して融液を生成し、Ａｕ製の攪拌用冶具を使用して融液を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板をＡｕ製の固定冶具に取り付けて炉内に投入し、８５０℃まで炉温を下げてから基板の片面を融液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が得られた。育成した単結晶膜を蛍光Ｘ線分析により組成分析したところＮａが検出され、組成はＢｉ_{１．２８３}Ｇｄ_{１．２００}Ｙｂ_{０．５００}Ｎａ_{０．０１７}Ｆｅ_{４．９６７}Ｓｎ_{０．０３３}Ｏ_１２であった。育成した単結晶膜を加工して、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、ファラデー回転子を作製した。作製したファラデー回転子から２０個抜き取り、波長１．５５μｍの光に対する光損失を評価した。ファラデー回転子の光損失は０〜０．０１ｄＢであり、極めて低損失であった。 (Example 5)
A crucible made of Au was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , SnO ₂ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. At this time, the Sn / Fe molar ratio was set to 0.020. The furnace temperature was raised to 950 ° C. to dissolve the material in the crucible to produce a melt, and the melt was stirred using a stirring jig made of Au. The CaMgZr-substituted GGG substrate was attached to a fixed fixture made of Au and placed in a furnace. After the furnace temperature was lowered to 850 ° C., one side of the substrate was brought into contact with the melt and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film having a thickness of 500 μm was obtained. The grown single crystal film Na was composition analysis by X-ray fluorescence analysis is detected, composition _{_{_{_{Bi 1.283 Gd 1.200 Yb 0.500 Na 0.017}}}} Fe 4.967 Sn 0.033 O 12 met It was. The grown single crystal film 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 produce a Faraday rotator. Twenty pieces were extracted from the prepared Faraday rotator and evaluated for light loss with respect to light having a wavelength of 1.55 μm. The optical loss of the Faraday rotator was 0 to 0.01 dB, which was extremely low loss.

（実施例６）
Ａｕ製のルツボにＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、ＳｎＯ_２、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。このときのＳｎ／Ｆｅモル比を０．００２とした。９５０℃まで炉温を上げてルツボ内の材料を溶解して融液を生成し、Ａｕ製の攪拌用冶具を使用して融液を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板をＡｕ製の固定冶具に取り付けて炉内に投入し、８５０℃まで炉温を下げてから基板の片面を融液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が得られた。育成した単結晶膜を蛍光Ｘ線分析により組成分析したところ、組成はＢｉ_{１．３００}Ｇｄ_{１．２００}Ｙｂ_{０．５００}Ｆｅ_{４．９９７}Ｓｎ_{０．００３}Ｏ_１２であり、Ｎａは検出できなかった。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膜の化学式は（ＢｉＧｄＹｂ）_{２．９９８}Ｎａ_{０．００２}（ＦｅＳｎ）_{５．０００}Ｏ_１２であることが分かった。育成した単結晶膜を加工して、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、ファラデー回転子を作製した。作製したファラデー回転子から２０個抜き取り、波長１．５５μｍの光に対する光損失を評価した。ファラデー回転子の光損失は０．２〜０．２５ｄＢであった。 (Example 6)
A crucible made of Au was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , SnO ₂ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. At this time, the Sn / Fe molar ratio was set to 0.002. The furnace temperature was raised to 950 ° C. to dissolve the material in the crucible to produce a melt, and the melt was stirred using a stirring jig made of Au. The CaMgZr-substituted GGG substrate was attached to a fixed fixture made of Au and placed in a furnace. After the furnace temperature was lowered to 850 ° C., one side of the substrate was brought into contact with the melt and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film having a thickness of 500 μm was obtained. The grown single crystal film was compositionally analyzed by X-ray fluorescence analysis, the composition is a _{_{_{_{Bi 1.300 Gd 1.200 Yb 0.500 Fe 4.997}}}} Sn 0.003 O 12, Na could be 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 film was (BiGdYb) _2.998 Na _0.002 (FeSn) _5.000 O ₁₂ . The grown single crystal film 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 produce a Faraday rotator. Twenty pieces were extracted from the prepared Faraday rotator and evaluated for light loss with respect to light having a wavelength of 1.55 μm. The optical loss of the Faraday rotator was 0.2 to 0.25 dB.

（実施例７）
Ａｕ製のルツボにＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、ＳｎＯ_２、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。このときのＳｎ／Ｆｅモル比を０．００３とした。９５０℃まで炉温を上げてルツボ内の材料を溶解して融液を生成し、Ａｕ製の攪拌用冶具を使用して融液を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板をＡｕ製の固定冶具に取り付けて炉内に投入し、８５０℃まで炉温を下げてから基板の片面を融液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が得られた。育成した単結晶膜を蛍光Ｘ線分析により組成分析したところ、組成はＢｉ_{１．３００}Ｇｄ_{１．２００}Ｙｂ_{０．５００}Ｆｅ_{４．９９４}Ｓｎ_{０．００６}Ｏ_１２であり、Ｎａは検出できなかった。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膜の化学式は（ＢｉＧｄＹｂ）_{２．９９７}Ｎａ_{０．００３}（ＦｅＳｎ）_{５．０００}Ｏ_１２であることが分かった。育成した単結晶膜を加工して、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、ファラデー回転子を作製した。作製したファラデー回転子から２０個抜き取り、波長１．５５μｍの光に対する光損失を評価した。ファラデー回転子の光損失は０．０４〜０．０７ｄＢであった。 (Example 7)
A crucible made of Au was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , SnO ₂ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. The Sn / Fe molar ratio at this time was 0.003. The furnace temperature was raised to 950 ° C. to dissolve the material in the crucible to produce a melt, and the melt was stirred using a stirring jig made of Au. The CaMgZr-substituted GGG substrate was attached to a fixed fixture made of Au and placed in a furnace. After the furnace temperature was lowered to 850 ° C., one side of the substrate was brought into contact with the melt and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film having a thickness of 500 μm was obtained. The grown single crystal film was compositionally analyzed by X-ray fluorescence analysis, the composition is a _{_{_{_{Bi 1.300 Gd 1.200 Yb 0.500 Fe 4.994}}}} Sn 0.006 O 12, Na could be detected. 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 film was found to be (BiGdYb) _2.997 Na _0.003 (FeSn) _5.000 O ₁₂ . The grown single crystal film 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 produce a Faraday rotator. Twenty pieces were extracted from the prepared Faraday rotator and evaluated for light loss with respect to light having a wavelength of 1.55 μm. The optical loss of the Faraday rotator was 0.04 to 0.07 dB.

（実施例８）
Ａｕ製のルツボにＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、ＲｈＯ_２、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。このときのＲｈ／Ｆｅモル比を０．００６とした。９５０℃まで炉温を上げてルツボ内の材料を溶解して融液を生成し、Ａｕ製の攪拌用冶具を使用して融液を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板をＡｕ製の固定冶具に取り付けて炉内に投入し、８５０℃まで炉温を下げてから基板の片面を融液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が得られた。育成した単結晶膜を蛍光Ｘ線分析により組成分析したところ、組成はＢｉ_{１．３００}Ｇｄ_{１．２００}Ｙｂ_{０．５００}Ｆｅ_{４．９９０}Ｒｈ_{０．０１０}Ｏ_１２であり、Ｎａは検出できなかった。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膜の化学式は（ＢｉＧｄＹｂ）_{２．９９５}Ｎａ_{０．００５}（ＦｅＲｈ）_{５．０００}Ｏ_１２であることが分かった。育成した単結晶膜を加工して、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、ファラデー回転子を作製した。作製したファラデー回転子から２０個抜き取り、波長１．５５μｍの光に対する光損失を評価した。ファラデー回転子の光損失は０〜０．０１ｄＢであり、極めて低損失であった。 (Example 8)
A crucible made of Au was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , RhO ₂ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. The Rh / Fe molar ratio at this time was set to 0.006. The furnace temperature was raised to 950 ° C. to dissolve the material in the crucible to produce a melt, and the melt was stirred using a stirring jig made of Au. The CaMgZr-substituted GGG substrate was attached to a fixed fixture made of Au and placed in a furnace. After the furnace temperature was lowered to 850 ° C., one side of the substrate was brought into contact with the melt and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film having a thickness of 500 μm was obtained. The grown single crystal film was compositionally analyzed by X-ray fluorescence analysis, the composition is a _{_{_{_{Bi 1.300 Gd 1.200 Yb 0.500 Fe 4.990}}}} Rh 0.010 O 12, Na could be detected. 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 film was found to be _{_{_{_{5.000 O 12 (BiGdYb) 2.995 Na}}}} 0.005 (FeRh). The grown single crystal film 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 produce a Faraday rotator. Twenty pieces were extracted from the prepared Faraday rotator and evaluated for light loss with respect to light having a wavelength of 1.55 μm. The optical loss of the Faraday rotator was 0 to 0.01 dB, which was extremely low loss.

（実施例９）
Ａｕ製のルツボにＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、ＲｕＯ_２、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。このときのＲｕ／Ｆｅモル比を０．００６とした。９５０℃まで炉温を上げてルツボ内の材料を溶解して融液を生成し、Ａｕ製の攪拌用冶具を使用して融液を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板をＡｕ製の固定冶具に取り付けて炉内に投入し、８５０℃まで炉温を下げてから基板の片面を融液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が得られた。育成した単結晶膜を蛍光Ｘ線分析により組成分析したところ、組成はＢｉ_{１．３００}Ｇｄ_{１．２００}Ｙｂ_{０．５００}Ｆｅ_{４．９９０}Ｒｕ_{０．０１０}Ｏ_１２であり、Ｎａは検出できなかった。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膜の化学式は（ＢｉＧｄＹｂ）_{２．９９５}Ｎａ_{０．００５}（ＦｅＲｕ）_{５．０００}Ｏ_１２であることが分かった。育成した単結晶膜を加工して、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、ファラデー回転子を作製した。作製したファラデー回転子から２０個抜き取り、波長１．５５μｍの光に対する光損失を評価した。ファラデー回転子の光損失は０〜０．０１ｄＢであり、極めて低損失であった。 Example 9
A crucible made of Au was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , RuO ₂ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. The Ru / Fe molar ratio at this time was set to 0.006. The furnace temperature was raised to 950 ° C. to dissolve the material in the crucible to produce a melt, and the melt was stirred using a stirring jig made of Au. The CaMgZr-substituted GGG substrate was attached to a fixed fixture made of Au and placed in a furnace. After the furnace temperature was lowered to 850 ° C., one side of the substrate was brought into contact with the melt and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film having a thickness of 500 μm was obtained. The grown single crystal film was compositionally analyzed by X-ray fluorescence analysis, the composition is a _{_{_{_{Bi 1.300 Gd 1.200 Yb 0.500 Fe 4.990}}}} Ru 0.010 O 12, Na could be detected. 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 film was found to be _{_{_{_{5.000 O 12 (BiGdYb) 2.995 Na}}}} 0.005 (FeRu). The grown single crystal film 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 produce a Faraday rotator. Twenty pieces were extracted from the prepared Faraday rotator and evaluated for light loss with respect to light having a wavelength of 1.55 μm. The optical loss of the Faraday rotator was 0 to 0.01 dB, which was extremely low loss.

（実施例１０）
Ａｕ製のルツボにＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、ＨｆＯ_２、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。このときのＨｆ／Ｆｅモル比を０．００６とした。９５０℃まで炉温を上げてルツボ内の材料を溶解して融液を生成し、Ａｕ製の攪拌用冶具を使用して融液を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板をＡｕ製の固定冶具に取り付けて炉内に投入し、８５０℃まで炉温を下げてから基板の片面を融液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が得られた。育成した単結晶膜を蛍光Ｘ線分析により組成分析したところ、組成はＢｉ_{１．３００}Ｇｄ_{１．２００}Ｙｂ_{０．５００}Ｆｅ_{４．９９０}Ｈｆ_{０．０１０}Ｏ_１２であり、Ｎａは検出できなかった。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膜の化学式は（ＢｉＧｄＹｂ）_{２．９９５}Ｎａ_{０．００５}（ＦｅＨｆ）_{５．０００}Ｏ_１２であることが分かった。育成した単結晶膜を加工して、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、ファラデー回転子を作製した。作製したファラデー回転子から２０個抜き取り、波長１．５５μｍの光に対する光損失を評価した。ファラデー回転子の光損失は０〜０．０１ｄＢであり、極めて低損失であった。 (Example 10)
A crucible made of Au was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , HfO ₂ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. At this time, the Hf / Fe molar ratio was set to 0.006. The furnace temperature was raised to 950 ° C. to dissolve the material in the crucible to produce a melt, and the melt was stirred using a stirring jig made of Au. The CaMgZr-substituted GGG substrate was attached to a fixed fixture made of Au and placed in a furnace. After the furnace temperature was lowered to 850 ° C., one side of the substrate was brought into contact with the melt and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film having a thickness of 500 μm was obtained. When the grown single crystal film was compositionally analyzed by X-ray fluorescence analysis, the composition is a _{_{_{_{Bi 1.300 Gd 1.200 Yb 0.500 Fe 4.990}}}} Hf 0.010 O 12, Na could be detected. 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 film was found to be _{_{_{_{5.000 O 12 (BiGdYb) 2.995 Na}}}} 0.005 (FeHf). The grown single crystal film 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 produce a Faraday rotator. Twenty pieces were extracted from the prepared Faraday rotator and evaluated for light loss with respect to light having a wavelength of 1.55 μm. The optical loss of the Faraday rotator was 0 to 0.01 dB, which was extremely low loss.

（実施例１１）
Ａｕ製のルツボにＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、ＺｒＯ_２、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。このときのＺｒ／Ｆｅモル比を０．００６とした。９５０℃まで炉温を上げてルツボ内の材料を溶解して融液を生成し、Ａｕ製の攪拌用冶具を使用して融液を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板をＡｕ製の固定冶具に取り付けて炉内に投入し、８５０℃まで炉温を下げてから基板の片面を融液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が得られた。育成した単結晶膜を蛍光Ｘ線分析により組成分析したところ、組成はＢｉ_{１．３００}Ｇｄ_{１．２００}Ｙｂ_{０．５００}Ｆｅ_{４．９９０}Ｚｒ_{０．０１０}Ｏ_１２であり、Ｎａは検出できなかった。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膜の化学式は（ＢｉＧｄＹｂ）_{２．９９５}Ｎａ_{０．００５}（ＦｅＺｒ）_{５．０００}Ｏ_１２であることが分かった。育成した単結晶膜を加工して、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、ファラデー回転子を作製した。作製したファラデー回転子から２０個抜き取り、波長１．５５μｍの光に対する光損失を評価した。ファラデー回転子の光損失は０〜０．０１ｄＢであり、極めて低損失であった。 (Example 11)
A crucible made of Au was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , ZrO ₂ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. The Zr / Fe molar ratio at this time was set to 0.006. The furnace temperature was raised to 950 ° C. to dissolve the material in the crucible to produce a melt, and the melt was stirred using a stirring jig made of Au. The CaMgZr-substituted GGG substrate was attached to a fixed fixture made of Au and placed in a furnace. After the furnace temperature was lowered to 850 ° C., one side of the substrate was brought into contact with the melt and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film having a thickness of 500 μm was obtained. The grown single crystal film was compositionally analyzed by X-ray fluorescence analysis, the composition is a _{_{_{_{Bi 1.300 Gd 1.200 Yb 0.500 Fe 4.990}}}} Zr 0.010 O 12, Na could be detected. 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 film was found to be _{_{_{_{5.000 O 12 (BiGdYb) 2.995 Na}}}} 0.005 (FeZr). The grown single crystal film 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 produce a Faraday rotator. Twenty pieces were extracted from the prepared Faraday rotator and evaluated for light loss with respect to light having a wavelength of 1.55 μm. The optical loss of the Faraday rotator was 0 to 0.01 dB, which was extremely low loss.

（実施例１２）
Ａｕ製のルツボにＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、Ｖ_２Ｏ_５、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。このときのＶ／Ｆｅモル比を０．００３とした。９５０℃まで炉温を上げてルツボ内の材料を溶解して融液を生成し、Ａｕ製の攪拌用冶具を使用して融液を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板をＡｕ製の固定冶具に取り付けて炉内に投入し、８５０℃まで炉温を下げてから基板の片面を融液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が得られた。育成した単結晶膜を蛍光Ｘ線分析により組成分析したところ、組成はＢｉ_{１．３００}Ｇｄ_{１．２００}Ｙｂ_{０．５００}Ｆｅ_{５．０００}Ｏ_１２であり、ＮａとＶは検出できなかった。次にＩＣＰ分析法で詳しく組成を評価したところ、ＮａとＶの含有量を確定できた。その結果、磁性ガーネット単結晶膜の化学式は（ＢｉＧｄＹｂ）_{２．９９５}Ｎａ_{０．００５}Ｆｅ_{４．９９５}Ｖ_{０．００５}Ｏ_１２であることが分かった。育成した単結晶膜を加工して、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、ファラデー回転子を作製した。作製したファラデー回転子から２０個抜き取り、波長１．５５μｍの光に対する光損失を評価した。ファラデー回転子の光損失は０〜０．０１ｄＢであり、極めて低損失であった。 (Example 12)
A crucible made of Au was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , V ₂ O ₅ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. The V / Fe molar ratio at this time was 0.003. The furnace temperature was raised to 950 ° C. to dissolve the material in the crucible to produce a melt, and the melt was stirred using a stirring jig made of Au. The CaMgZr-substituted GGG substrate was attached to a fixed fixture made of Au and placed in a furnace. After the furnace temperature was lowered to 850 ° C., one side of the substrate was brought into contact with the melt and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film having a thickness of 500 μm was obtained. Composition analysis of the grown single crystal film by fluorescent X-ray analysis revealed that the composition was Bi _1.300 Gd _1.200 Yb _0.500 Fe _5.000 O ₁₂ , and Na and V could not be detected. Next, when the composition was evaluated in detail by ICP analysis, the contents of Na and V were confirmed. As a result, the chemical formula of the magnetic garnet single crystal film was found to be _{_{_{_{(BiGdYb) 2.995 Na 0.005 Fe 4.995}}}} V 0.005 O 12. The grown single crystal film 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 produce a Faraday rotator. Twenty pieces were extracted from the prepared Faraday rotator and evaluated for light loss with respect to light having a wavelength of 1.55 μm. The optical loss of the Faraday rotator was 0 to 0.01 dB, which was extremely low loss.

（実施例１３）
Ａｕ製のルツボにＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、Ｓｂ_２Ｏ_５、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。このときのＳｂ／Ｆｅモル比を０．００３とした。９５０℃まで炉温を上げてルツボ内の材料を溶解して融液を生成し、Ａｕ製の攪拌用冶具を使用して融液を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板をＡｕ製の固定冶具に取り付けて炉内に投入し、８５０℃まで炉温を下げてから基板の片面を融液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が得られた。育成した単結晶膜を蛍光Ｘ線分析により組成分析したところ、組成はＢｉ_{１．３００}Ｇｄ_{１．２００}Ｙｂ_{０．５００}Ｆｅ_{５．０００}Ｏ_１２であり、ＮａとＳｂは検出できなかった。次にＩＣＰ分析法で詳しく組成を評価したところ、ＮａとＳｂの含有量を確定できた。その結果、磁性ガーネット単結晶膜の化学式は（ＢｉＧｄＹｂ）_{２．９９５}Ｎａ_{０．００５}Ｆｅ_{４．９９５}Ｓｂ_{０．００５}Ｏ_１２であることが分かった。育成した単結晶膜を加工して、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、ファラデー回転子を作製した。作製したファラデー回転子から２０個抜き取り、波長１．５５μｍの光に対する光損失を評価した。ファラデー回転子の光損失は０〜０．０１ｄＢであり、極めて低損失であった。 (Example 13)
A crucible made of Au was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , Sb ₂ O ₅ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. The Sb / Fe molar ratio at this time was set to 0.003. The furnace temperature was raised to 950 ° C. to dissolve the material in the crucible to produce a melt, and the melt was stirred using a stirring jig made of Au. The CaMgZr-substituted GGG substrate was attached to a fixed fixture made of Au and placed in a furnace. After the furnace temperature was lowered to 850 ° C., one side of the substrate was brought into contact with the melt and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film having a thickness of 500 μm was obtained. Composition analysis of the grown single crystal film by fluorescent X-ray analysis revealed that the composition was Bi _1.300 Gd _1.200 Yb _0.500 Fe _5.000 O ₁₂ and Na and Sb could not be detected. Next, when the composition was evaluated in detail by ICP analysis, the contents of Na and Sb were confirmed. As a result, it was found that the chemical formula of the magnetic garnet single crystal film was (BiGdYb) _2.995 Na _0.005 Fe _4.995 Sb _0.005 O ₁₂ . The grown single crystal film 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 produce a Faraday rotator. Twenty pieces were extracted from the prepared Faraday rotator and evaluated for light loss with respect to light having a wavelength of 1.55 μm. The optical loss of the Faraday rotator was 0 to 0.01 dB, which was extremely low loss.

（実施例１４）
Ａｕ製のルツボにＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、Ｎｂ_２Ｏ_５、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。このときのＮｂ／Ｆｅモル比を０．００３とした。９５０℃まで炉温を上げてルツボ内の材料を溶解して融液を生成し、Ａｕ製の攪拌用冶具を使用して融液を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板をＡｕ製の固定冶具に取り付けて炉内に投入し、８５０℃まで炉温を下げてから基板の片面を融液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が得られた。育成した単結晶膜を蛍光Ｘ線分析により組成分析したところ、組成はＢｉ_{１．３００}Ｇｄ_{１．２００}Ｙｂ_{０．５００}Ｆｅ_{５．０００}Ｏ_１２であり、ＮａとＮｂは検出できなかった。次にＩＣＰ分析法で詳しく組成を評価したところ、ＮａとＮｂの含有量を確定できた。その結果、磁性ガーネット単結晶膜の化学式は（ＢｉＧｄＹｂ）_{２．９９５}Ｎａ_{０．００５}Ｆｅ_{４．９９５}Ｎｂ_{０．００５}Ｏ_１２であることが分かった。育成した単結晶膜を加工して、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、ファラデー回転子を作製した。作製したファラデー回転子から２０個抜き取り、波長１．５５μｍの光に対する光損失を評価した。ファラデー回転子の光損失は０〜０．０１ｄＢであり、極めて低損失であった。 (Example 14)
An Au crucible was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , Nb ₂ O ₅ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. The Nb / Fe molar ratio at this time was set to 0.003. The furnace temperature was raised to 950 ° C. to dissolve the material in the crucible to produce a melt, and the melt was stirred using a stirring jig made of Au. The CaMgZr-substituted GGG substrate was attached to a fixed fixture made of Au and placed in a furnace. After the furnace temperature was lowered to 850 ° C., one side of the substrate was brought into contact with the melt and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film having a thickness of 500 μm was obtained. Composition analysis of the grown single crystal film by fluorescent X-ray analysis revealed that the composition was Bi _1.300 Gd _1.200 Yb _0.500 Fe _5.000 O ₁₂ and Na and Nb could not be detected. Next, when the composition was evaluated in detail by ICP analysis, the contents of Na and Nb were confirmed. As a result, the chemical formula of the magnetic garnet single crystal film was found to be _{_{_{_{(BiGdYb) 2.995 Na 0.005 Fe 4.995}}}} Nb 0.005 O 12. The grown single crystal film 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 produce a Faraday rotator. Twenty pieces were extracted from the prepared Faraday rotator and evaluated for light loss with respect to light having a wavelength of 1.55 μm. The optical loss of the Faraday rotator was 0 to 0.01 dB, which was extremely low loss.

（実施例１５）
Ａｕ製のルツボにＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、Ｔａ_２Ｏ_５、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。このときのＴａ／Ｆｅモル比を０．００３とした。９５０℃まで炉温を上げてルツボ内の材料を溶解して融液を生成し、Ａｕ製の攪拌用冶具を使用して融液を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板をＡｕ製の固定冶具に取り付けて炉内に投入し、８５０℃まで炉温を下げてから基板の片面を融液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が得られた。育成した単結晶膜を蛍光Ｘ線分析により組成分析したところ、組成はＢｉ_{１．３００}Ｇｄ_{１．２００}Ｙｂ_{０．５００}Ｆｅ_{５．０００}Ｏ_１２であり、ＮａとＴａは検出できなかった。次にＩＣＰ分析法で詳しく組成を評価したところ、ＮａとＴａの含有量を確定できた。その結果、磁性ガーネット単結晶膜の化学式は（ＢｉＧｄＹｂ）_{２．９９５}Ｎａ_{０．００５}Ｆｅ_{４．９９５}Ｔａ_{０．００５}Ｏ_１２であることが分かった。育成した単結晶膜を加工して、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、ファラデー回転子を作製した。作製したファラデー回転子から２０個抜き取り、波長１．５５μｍの光に対する光損失を評価した。ファラデー回転子の光損失は０〜０．０１ｄＢであり、極めて低損失であった。 (Example 15)
A crucible made of Au was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , Ta ₂ O ₅ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. The Ta / Fe molar ratio at this time was 0.003. The furnace temperature was raised to 950 ° C. to dissolve the material in the crucible to produce a melt, and the melt was stirred using a stirring jig made of Au. The CaMgZr-substituted GGG substrate was attached to a fixed fixture made of Au and placed in a furnace. After the furnace temperature was lowered to 850 ° C., one side of the substrate was brought into contact with the melt and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film having a thickness of 500 μm was obtained. Composition analysis of the grown single crystal film by X-ray fluorescence analysis revealed that the composition was Bi _1.300 Gd _1.200 Yb _0.500 Fe _5.000 O ₁₂ and Na and Ta could not be detected. Next, when the composition was evaluated in detail by ICP analysis, the contents of Na and Ta could be determined. As a result, the chemical formula of the magnetic garnet single crystal film was found to be _{_{_{_{(BiGdYb) 2.995 Na 0.005 Fe 4.995}}}} Ta 0.005 O 12. The grown single crystal film 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 produce a Faraday rotator. Twenty pieces were extracted from the prepared Faraday rotator and evaluated for light loss with respect to light having a wavelength of 1.55 μm. The optical loss of the Faraday rotator was 0 to 0.01 dB, which was extremely low loss.

（実施例１６）
Ａｕ製のルツボにＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、ＷＯ_３、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。このときのＷ／Ｆｅモル比を０．００２とした。９５０℃まで炉温を上げてルツボ内の材料を溶解して融液を生成し、Ａｕ製の攪拌用冶具を使用して融液を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板をＡｕ製の固定冶具に取り付けて炉内に投入し、８５０℃まで炉温を下げてから基板の片面を融液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が得られた。育成した単結晶膜を蛍光Ｘ線分析により組成分析したところ、組成はＢｉ_{１．３００}Ｇｄ_{１．２００}Ｙｂ_{０．５００}Ｆｅ_{５．０００}Ｏ_１２であり、ＮａとＷは検出できなかった。次にＩＣＰ分析法で詳しく組成を評価したところ、ＮａとＷの含有量を確定できた。その結果、磁性ガーネット単結晶膜の化学式は（ＢｉＧｄＹｂ）_{２．９９５}Ｎａ_{０．００５}Ｆｅ_{４．９９７}Ｗ_{０．００３}Ｏ_１２であることが分かった。育成した単結晶膜を加工して、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、ファラデー回転子を作製した。作製したファラデー回転子から２０個抜き取り、波長１．５５μｍの光に対する光損失を評価した。ファラデー回転子の光損失は０〜０．０１ｄＢであり、極めて低損失であった。 (Example 16)
A crucible made of Au was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , WO ₃ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. The W / Fe molar ratio at this time was 0.002. The furnace temperature was raised to 950 ° C. to dissolve the material in the crucible to produce a melt, and the melt was stirred using a stirring jig made of Au. The CaMgZr-substituted GGG substrate was attached to a fixed fixture made of Au and placed in a furnace. After the furnace temperature was lowered to 850 ° C., one side of the substrate was brought into contact with the melt and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film having a thickness of 500 μm was obtained. Composition analysis of the grown single crystal film by X-ray fluorescence analysis revealed that the composition was Bi _1.300 Gd _1.200 Yb _0.500 Fe _5.000 O ₁₂ and Na and W could not be detected. Next, when the composition was evaluated in detail by ICP analysis, the contents of Na and W were confirmed. As a result, it was found that the chemical formula of the magnetic garnet single crystal film was (BiGdYb) _2.995 Na _0.005 Fe _4.997 W _0.003 O ₁₂ . The grown single crystal film 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 produce a Faraday rotator. Twenty pieces were extracted from the prepared Faraday rotator and evaluated for light loss with respect to light having a wavelength of 1.55 μm. The optical loss of the Faraday rotator was 0 to 0.01 dB, which was extremely low loss.

（実施例１７）
Ａｕ製のルツボにＧｄ_２Ｏ_３、Ｙｂ_２Ｏ_３、Ｆｅ_２Ｏ_３、ＭｏＯ_３、Ｂ_２Ｏ_３、Ｂｉ_２Ｏ_３、ＮａＯＨを充填して、電気炉に配置した。このときのＭｏ／Ｆｅモル比を０．００２とした。９５０℃まで炉温を上げてルツボ内の材料を溶解して融液を生成し、Ａｕ製の攪拌用冶具を使用して融液を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板をＡｕ製の固定冶具に取り付けて炉内に投入し、８５０℃まで炉温を下げてから基板の片面を融液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が得られた。育成した単結晶膜を蛍光Ｘ線分析により組成分析したところ、組成はＢｉ_{１．３００}Ｇｄ_{１．２００}Ｙｂ_{０．５００}Ｆｅ_{５．０００}Ｏ_１２であり、ＮａとＭｏは検出できなかった。次にＩＣＰ分析法で詳しく組成を評価したところ、ＮａとＭｏの含有量を確定できた。その結果、磁性ガーネット単結晶膜の化学式は（ＢｉＧｄＹｂ）_{２．９９５}Ｎａ_{０．００５}Ｆｅ_{４．９９７}Ｍｏ_{０．００３}Ｏ_１２であることが分かった。育成した単結晶膜を加工して、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、ファラデー回転子を作製した。作製したファラデー回転子から２０個抜き取り、波長１．５５μｍの光に対する光損失を評価した。ファラデー回転子の光損失は０〜０．０１ｄＢであり、極めて低損失であった。 (Example 17)
A crucible made of Au was filled with Gd ₂ O ₃ , Yb ₂ O ₃ , Fe ₂ O ₃ , MoO ₃ , B ₂ O ₃ , Bi ₂ O ₃ , and NaOH and placed in an electric furnace. The Mo / Fe molar ratio at this time was 0.002. The furnace temperature was raised to 950 ° C. to dissolve the material in the crucible to produce a melt, and the melt was stirred using a stirring jig made of Au. The CaMgZr-substituted GGG substrate was attached to a fixed fixture made of Au and placed in a furnace. After the furnace temperature was lowered to 850 ° C., one side of the substrate was brought into contact with the melt and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film having a thickness of 500 μm was obtained. Composition analysis of the grown single crystal film by fluorescent X-ray analysis revealed that the composition was Bi _1.300 Gd _1.200 Yb _0.500 Fe _5.000 O ₁₂ , and Na and Mo could not be detected. Next, when the composition was evaluated in detail by ICP analysis, the contents of Na and Mo could be determined. As a result, the chemical formula of the magnetic garnet single crystal film was found to be _{_{_{_{(BiGdYb) 2.995 Na 0.005 Fe 4.997}}}} Mo 0.003 O 12. The grown single crystal film 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 produce a Faraday rotator. Twenty pieces were extracted from the prepared Faraday rotator and evaluated for light loss with respect to light having a wavelength of 1.55 μm. The optical loss of the Faraday rotator was 0 to 0.01 dB, which was extremely low loss.

（比較例）
Ａｕ製のルツボに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内の材料を溶解して融液を生成し、Ａｕ製の攪拌用冶具を使用して融液を攪拌した。ＣａＭｇＺｒ置換ＧＧＧ基板をＡｕ製の固定冶具に取り付けて炉内に投入し、８５０℃まで炉温を下げてから基板の片面を融液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が得られた。育成した単結晶膜を蛍光Ｘ線分析により組成分析したところ、組成はＢｉ_{１．３００}Ｇｄ_{１．２００}Ｙｂ_{０．５００}Ｆｅ_{５．０００}Ｏ_１２であり、Ｎａは検出できなかった。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膜の化学式は（ＢｉＧｄＹｂ）_{２．９９８}Ｎａ_{０．００２}Ｆｅ_{５．０００}Ｏ_１２であることが分かった。育成した単結晶膜を加工して、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、ファラデー回転子を作製した。作製したファラデー回転子から２０個抜き取り、波長１．５５μｍの光に対する光損失を評価した。ファラデー回転子の光損失は３．０〜３．５ｄＢであり、極めて高損失であった。 (Comparative example)
A crucible made of Au 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. to dissolve the material in the crucible to produce a melt, and the melt was stirred using a stirring jig made of Au. The CaMgZr-substituted GGG substrate was attached to a fixed fixture made of Au and placed in a furnace. After the furnace temperature was lowered to 850 ° C., one side of the substrate was brought into contact with the melt and epitaxial growth was performed for 40 hours. A magnetic garnet single crystal film having a thickness of 500 μm was obtained. Composition analysis of the grown single crystal film by fluorescent X-ray analysis revealed that the composition was Bi _1.300 Gd _1.200 Yb _0.500 Fe _5.000 O ₁₂ and Na could not be 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 film was (BiGdYb) _2.998 Na _0.002 Fe _5.000 O ₁₂ . The grown single crystal film 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 produce a Faraday rotator. Twenty pieces were extracted from the prepared Faraday rotator and evaluated for light loss with respect to light having a wavelength of 1.55 μm. The optical loss of the Faraday rotator was 3.0 to 3.5 dB, which was extremely high loss.

図１は、上記の実施例及び比較例について、育成した磁性ガーネット単結晶のＮａ量β、Ｍ２量γ、Ｍ３量δ、Ｍ４量ε、γ＋δ＋ε及びγ＋２δ＋３ε、並びに作製したファラデー回転子の光損失（ｄＢ）をまとめて示している。図１に示すように、本実施例の磁性ガーネット単結晶は、Ｎａを含有するとともにＭ２、Ｍ３又はＭ４のいずれかを含有している（γ＋δ＋ε＞０）。一方、比較例の磁性ガーネット単結晶は、Ｎａを含有しているがＭ２、Ｍ３及びＭ４をいずれも含有していない（γ＋δ＋ε＝０）。Ｍ２、Ｍ３又はＭ４のいずれかを含有する本実施例の磁性ガーネット単結晶を用いたファラデー回転子は、比較例の磁性ガーネット単結晶を用いたファラデー回転子よりも低損失であることが分かる。特に、Ｍ２量γ、Ｍ３量δ及びＭ４量εがγ＋２δ＋３ε≧０．００７の関係を満たす場合（実施例１乃至５及び８乃至１７）には、Ｐｂを含む溶媒から育成した磁性ガーネット単結晶を用いて作製した従来のファラデー回転子（例えば光損失０．０５ｄＢ以下）と比較しても極めて低損失のファラデー回転子が得られる。 FIG. 1 shows the amount of Na of the grown magnetic garnet single crystal, M2 amount γ, M3 amount δ, M4 amount ε, γ + δ + ε and γ + 2δ + 3ε, and the optical loss of the prepared Faraday rotator for the above examples and comparative examples. dB) is shown together. As shown in FIG. 1, the magnetic garnet single crystal of the present example contains Na and contains any of M2, M3, and M4 (γ + δ + ε> 0). On the other hand, the magnetic garnet single crystal of the comparative example contains Na but does not contain any of M2, M3 and M4 (γ + δ + ε = 0). It can be seen that the Faraday rotator using the magnetic garnet single crystal of this example containing either M2, M3 or M4 has a lower loss than the Faraday rotator using the magnetic garnet single crystal of the comparative example. In particular, when the M2 amount γ, the M3 amount δ, and the M4 amount ε satisfy the relationship of γ + 2δ + 3ε ≧ 0.007 (Examples 1 to 5 and 8 to 17), a magnetic garnet single crystal grown from a solvent containing Pb is used. Even when compared with a conventional Faraday rotator (for example, an optical loss of 0.05 dB or less) manufactured by using the same, a very low loss Faraday rotator can be obtained.

本発明の一実施の形態の実施例１乃至１７及び比較例の磁性ガーネット単結晶のＮａ量β、Ｍ２量γ、Ｍ３量δ及びＭ４量ε、並びにファラデー回転子の光損失をまとめて示す表である。Table showing collectively the Na amount β, M2 amount γ, M3 amount δ and M4 amount ε of the magnetic garnet single crystals of one embodiment of the present invention and the comparative example, and the optical loss of the Faraday rotator. It is.

Explanation of symbols

β Ｎａ量
γ Ｍ２量
δ Ｍ３量
ε Ｍ４量 β Na amount γ M2 amount δ M3 amount ε M4 amount

Claims

Chemical Formula Bi _α Na _β M1 _3-α-β Fe _5-γ-δ-ε M2 _γ M3 _δ M4 _ε O ₁₂
(M1 is at least one element selected from Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and M2 is Sn, Ru, Hf. M3 is at least one element selected from V, Sb, Nb and Ta, M4 is at least one element selected from W and Mo, and 0 0.5 ≦ α ≦ 2.0, 0 <β ≦ 2.4, 0 <3-α−β <2.5, 0 <γ + δ + ε ≦ 0.033 )
A magnetic garnet single crystal characterized by the following:

The magnetic garnet single crystal according to claim 1,
The magnetic garnet single crystal, wherein γ, δ, and ε satisfy a relationship of γ + 2δ + 3ε ≧ 0.007.

An optical element manufactured using the magnetic garnet single crystal according to claim 1.