JP2003057404A - Antireflection film for faraday rotator - Google Patents
Antireflection film for faraday rotatorInfo
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- JP2003057404A JP2003057404A JP2001250857A JP2001250857A JP2003057404A JP 2003057404 A JP2003057404 A JP 2003057404A JP 2001250857 A JP2001250857 A JP 2001250857A JP 2001250857 A JP2001250857 A JP 2001250857A JP 2003057404 A JP2003057404 A JP 2003057404A
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- layer
- film
- refractive index
- single crystal
- magnetic garnet
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- Polarising Elements (AREA)
- Surface Treatment Of Optical Elements (AREA)
- Optical Modulation, Optical Deflection, Nonlinear Optics, Optical Demodulation, Optical Logic Elements (AREA)
Abstract
Description
【０００１】[0001]
【発明の属する技術分野】本発明は、光アイソレータ、
光サーキュレータ等の一部品を構成する磁性ガーネット
単結晶から成るファラデー回転子に係り、特に、ファラ
デー回転子表面に施される反射防止膜の改良に関するも
のである。TECHNICAL FIELD The present invention relates to an optical isolator,
The present invention relates to a Faraday rotator made of a magnetic garnet single crystal that constitutes one part of an optical circulator or the like, and more particularly to improvement of an antireflection film formed on the surface of a Faraday rotator.
【０００２】[0002]
【従来の技術】従来より、光アイソレータ等に組込まれ
る磁性ガーネット単結晶の表面には、半導体レーザへ反
射光が戻るのを防ぐために反射防止膜が施されている。2. Description of the Related Art Conventionally, a surface of a magnetic garnet single crystal incorporated in an optical isolator or the like is provided with an antireflection film to prevent reflected light from returning to a semiconductor laser.
【０００３】ところで、磁性ガーネット単結晶の表面に
施される反射防止膜の屈折率をｎf、磁性ガーネット単
結晶の屈折率をｎs、媒質の屈折率をｎ0とした場合、以
下の数式（１）で示される反射防止の条件式を満たせ
ば、単層膜で反射率を０にすることができる。When the refractive index of the antireflection film formed on the surface of the magnetic garnet single crystal is n f , the refractive index of the magnetic garnet single crystal is n s , and the refractive index of the medium is n 0 , If the conditional expression for antireflection shown in (1) is satisfied, the reflectance can be made zero with the single layer film.
【０００４】[0004]
【数７】
しかしながら、磁性ガーネット単結晶の屈折率ｎsは通
常２．２〜２．４であるために、媒質が空気のとき（ｎ
0＝１）には、上記反射防止の条件式を満足するような
屈折率を有する安定な光学薄膜材料は存在しなかった。[Equation 7] However, since the refractive index n s of the magnetic garnet single crystal is normally 2.2 to 2.4, when the medium is air (n
In 0 = 1), there was no stable optical thin film material having a refractive index satisfying the above antireflection conditional expression.
【０００５】そこで、空気側の第１層と磁性ガーネット
単結晶側の第３層にＳｉＯ2を用い、第１層と第３層に
挟まれた第２層にＡｌ2Ｏ3、ＺｒＯ2、ＴｉＯ2、Ｔａ2
Ｏ5、ＨｆＯ2、Ｙ2Ｏ3の中から選ばれる１種を用いた３
層等価膜が反射防止膜として用いられていた（特開平４
−２３０７０１号公報参照）。Therefore, SiO 2 is used for the first layer on the air side and the third layer on the magnetic garnet single crystal side, and Al 2 O 3 , ZrO 2 is used for the second layer sandwiched between the first layer and the third layer. TiO 2 , Ta 2
O 5, HfO 2, Y 2 3 using one selected from among O 3
A layer-equivalent film was used as an antireflection film (Japanese Patent Laid-Open No. Hei 4)
-230701 gazette).
【０００６】さて、最近、光アイソレータをより小型化
するため、偏光子等の光学部品を磁性ガーネット単結晶
に接着剤で張り合わせて適用する方法が行われている。
この場合、上記磁性ガーネット単結晶の表面には、接着
剤に対する反射防止膜を施すことになる。Recently, in order to further miniaturize the optical isolator, a method of applying an optical component such as a polarizer to a magnetic garnet single crystal with an adhesive is applied.
In this case, an antireflection film for the adhesive is applied to the surface of the magnetic garnet single crystal.
【０００７】そして、媒質が接着剤のときには、媒質が
空気の場合と異なり、その屈折率ｎ 0は１．４〜１．
６、代表的なものでは１．５であるため、上記反射防止
の条件式をほぼ満足した屈折率を有する安定な光学薄膜
材料が存在する。例えば、ＨｆＯ2は成膜条件によって
屈折率が異なるが、代表的な成膜条件では屈折率１．９
であり、単層でも比較的低い反射率の反射防止膜が得ら
れている。When the medium is an adhesive, the medium is
Unlike air, its refractive index n 0Is 1.4 to 1.
6, the typical one is 1.5, so the above anti-reflection
Stable optical thin film with a refractive index that almost satisfies the conditional expression
Material is present. For example, HfO2Depends on the film forming conditions
Although the refractive index is different, the refractive index is 1.9 under typical film forming conditions.
Therefore, it is possible to obtain an antireflection film with a relatively low reflectance even with a single layer.
Has been.
【０００８】但し、ＨｆＯ2膜はポーラスな構造を有す
るため、磁性ガーネット単結晶に対して付着力が弱いと
いう欠点があり、更に、接着剤がＨｆＯ2膜に浸透して
屈折率を変化させてしまう場合があった。However, since the HfO 2 film has a porous structure, it has a drawback that it has a weak adhesive force with respect to the magnetic garnet single crystal, and further the adhesive penetrates into the HfO 2 film to change the refractive index. There were times when it ended up.
【０００９】尚、対接着剤用の反射防止膜としては、上
記ＨｆＯ2単層膜以外にも、ＴｉＯ2とＳｉＯ2を交互に
４層積層した多層膜による反射防止膜も提案されている
（特開平２−６９７０１号公報参照）。As the antireflection film for the adhesive, in addition to the HfO 2 single layer film, an antireflection film composed of a multilayer film in which four layers of TiO 2 and SiO 2 are alternately laminated has been proposed ( See Japanese Patent Application Laid-Open No. 2-69701).
【００１０】しかし、ＴｉＯ2は結晶化し易いため、成
膜中に相が変化して安定した屈折率の膜が得難く、散乱
が多いといった問題があった。屈折率が安定しないと、
設計値通りの反射率を有する反射防止膜を得ることがで
きない。また、ＴｉＯ2を電子ビーム蒸着法により成膜
する際には、スプラッシュと呼ばれる現象により、蒸着
源からＴｉＯ2が飛び散り、膜中に黒い欠陥が入ること
もあった。However, since TiO 2 is easily crystallized, there is a problem that it is difficult to obtain a film having a stable refractive index due to a change in phase during film formation and a large amount of scattering occurs. If the refractive index is not stable,
It is not possible to obtain an antireflection film having a reflectance as designed. Further, when forming TiO 2 by an electron beam evaporation method, due to a phenomenon called splash, TiO 2 was scattered from the evaporation source, and black defects were sometimes included in the film.
【００１１】[0011]
【発明が解決しようとする課題】本発明はこのような問
題点に着目してなされたもので、その課題とするところ
は、上記磁性ガーネット単結晶に対して付着力が強いと
共に、屈折率の安定した、散乱の少ない対接着剤用の反
射防止膜をできるだけ少ない層数で提供することにあ
る。The present invention has been made by paying attention to such a problem. The problem is that the magnetic garnet single crystal has a strong adhesive force and a high refractive index. The object is to provide a stable, low-scattering antireflection film for adhesives with a minimum number of layers.
【００１２】[0012]
【課題を解決するための手段】そこで、上記課題を解決
するため鋭意検討した結果、ＳｉＯ2が磁性ガーネット
単結晶に対して強い付着力を有すること、耐候性を考慮
すると反射防止膜の表面層はＳｉＯ2が好ましいこと、
更に屈折率の高い光学薄膜材料の中でＨｆＯ2、Ｚｒ
Ｏ2、Ｔａ2Ｏ5が安定した屈折率を有しており散乱も少
ないことを見出すに至った。本発明はこのような技術的
検討を経て完成されたものである。Therefore, as a result of extensive studies to solve the above problems, as a result of considering that SiO 2 has a strong adhesive force to a magnetic garnet single crystal and the weather resistance, the surface layer of the antireflection film is considered. Is preferably SiO 2 .
Among optical thin film materials with higher refractive index, HfO 2 , Zr
It has been found that O 2 and Ta 2 O 5 have a stable refractive index and little scattering. The present invention has been completed through such technical studies.
【００１３】すなわち、請求項１に係る発明は、光学用
接着剤を介し光学部品に張り合わせて使用される磁性ガ
ーネット単結晶から成るファラデー回転子の反射防止膜
を前提とし、接着剤側の第１層と磁性ガーネット単結晶
側の第３層がＳｉＯ2で、第１層と第３層に挟まれた第
２層がＨｆＯ2、ＺｒＯ2、Ｔａ2Ｏ5の中から選ばれたい
ずれか１種であると共に、下記数式（２）〜（４）を満
たす３層等価膜により構成されることを特徴とする。That is, the invention according to claim 1 is premised on an antireflection film of a Faraday rotator made of a magnetic garnet single crystal which is used by being bonded to an optical component through an optical adhesive, and the first adhesive-side film is provided. The layer and the third layer on the magnetic garnet single crystal side are made of SiO 2 , and the second layer sandwiched between the first layer and the third layer is selected from HfO 2 , ZrO 2 and Ta 2 O 5. In addition to being a seed, it is characterized by being constituted by a three-layer equivalent film that satisfies the following mathematical formulas (2) to (4).
【００１４】[0014]
【数８】 [Equation 8]
【００１５】[0015]
【数９】 [Equation 9]
【００１６】[0016]
【数１０】
但し、σ1＝２πｎ1ｄ1／λ0、σ2＝２πｎ2ｄ2／λ0、
ｎ1＜ｎf＜ｎ2であり、かつ、ｎfは磁性ガーネット単結
晶の屈折率をｎs、接着剤の屈折率をｎ0とした場合に下
記数式（１）から求まる単層で反射率が０になる光学薄
膜材料の屈折率、ｎ1は第１層と第３層の屈折率、ｄ1は
第１層と第３層の物理的膜厚、ｎ2は第２層の屈折率、
ｄ2は第２層の物理的膜厚、λ0は設計中心波長である。[Equation 10] However, σ 1 = 2πn 1 d 1 / λ 0 , σ 2 = 2πn 2 d 2 / λ 0 ,
n 1 <n f <n 2 and n f is reflected by a single layer obtained from the following formula (1) when the refractive index of the magnetic garnet single crystal is n s and the refractive index of the adhesive is n 0. Refractive index of the optical thin film material whose index becomes 0, n 1 is the refractive index of the first and third layers, d 1 is the physical film thickness of the first and third layers, n 2 is the refractive index of the second layer rate,
d 2 is the physical film thickness of the second layer, and λ 0 is the design center wavelength.
【００１７】[0017]
【数１１】
この請求項１記載の発明に係る反射防止膜によれば、第
１層と第３層について緻密な膜が形成可能なＳｉＯ2を
適用することで強い付着力、耐候性が確保され、また、
第２層についてＨｆＯ2、ＺｒＯ2、Ｔａ2Ｏ5の中から選
ばれたいずれか１種を適用することで３層という比較的
少ない層数で低反射率が達成され、更に、上記数式
（２）〜（４）を満たす３層等価膜とすることで第１層
と第３層の膜厚を同じに設定できその成膜が容易とな
る。[Equation 11] According to the antireflection film of the invention described in claim 1, strong adhesion and weather resistance are secured by applying SiO 2 capable of forming a dense film for the first layer and the third layer, and
By applying any one selected from HfO 2 , ZrO 2 , and Ta 2 O 5 to the second layer, a low reflectance is achieved with a relatively small number of layers of three, and the above formula ( By forming a three-layer equivalent film satisfying 2) to 4), the film thicknesses of the first layer and the third layer can be set to be the same, and the film formation can be facilitated.
【００１８】次に、請求項２に係る発明は、光学用接着
剤を介し光学部品に張り合わせて使用される磁性ガーネ
ット単結晶から成るファラデー回転子の反射防止膜を前
提とし、接着剤側の第１層と磁性ガーネット単結晶側の
第３層がＳｉＯ2で、第１層と第３層に挟まれた第２層
がＨｆＯ2、ＺｒＯ2、Ｔａ2Ｏ5の中から選ばれたいずれ
か１種であると共に、下記数式（５）〜（６）から求ま
る設計中心波長λ0付近の反射率Ｒが最も低くなる条件
を満たした３層膜により構成され、かつ、第１層である
ＳｉＯ2の物理的膜厚が２００ｎｍ以上であることを特
徴とする。Next, the invention according to claim 2 is premised on an antireflection film of a Faraday rotator made of a magnetic garnet single crystal which is used by being bonded to an optical component through an optical adhesive, and the adhesive-side first film is used. One layer and the third layer on the magnetic garnet single crystal side are made of SiO 2 , and the second layer sandwiched between the first layer and the third layer is selected from HfO 2 , ZrO 2 , and Ta 2 O 5 . SiO which is a first layer and which is a first layer and is composed of a three-layer film that satisfies the condition that the reflectance R is the lowest near the design center wavelength λ 0 obtained from the following mathematical formulas (5) to (6). The physical film thickness of 2 is 200 nm or more.
【００１９】[0019]
【数１２】 [Equation 12]
【００２０】[0020]
【数１３】
但し、σj＝２πｎjｄj／（λ／λ0）、ｉ2＝−１であ
り、かつ、λは反射率Ｒを計算したい波長、ｄjは第ｊ
層の物理的膜厚、ｎjは第ｊ層の屈折率、ｎsは磁性ガー
ネット単結晶の屈折率、ｎ0は接着剤の屈折率である。[Equation 13] However, σ j = 2πn j dj / (λ / λ 0 ), i 2 = −1, λ is the wavelength for which the reflectance R is to be calculated, and dj is the j-th wavelength.
The physical thickness of the layer, n j is the refractive index of the j-th layer, n s is the refractive index of the magnetic garnet single crystal, and n 0 is the refractive index of the adhesive.
【００２１】請求項２記載の発明に係る反射防止膜によ
れば、接着剤側の第１層が緻密な膜を形成可能なＳｉＯ
2で構成されかつその物理的膜厚が２００ｎｍ以上と厚
いため、請求項１記載の発明に係る反射防止膜と比較し
てその耐候性に優れている。According to the antireflection film of the second aspect of the invention, the first layer on the adhesive side is a SiO film which can form a dense film.
Since it is composed of 2 and has a large physical film thickness of 200 nm or more, it is excellent in weather resistance as compared with the antireflection film according to the invention of claim 1.
【００２２】また、請求項３に係る発明は、請求項２記
載の発明に係る反射防止膜を前提とし、上記３層膜にお
ける３層合計の光学的膜厚が０．２５λ0〜０．５λ0の
範囲を満たしていることを特徴とする。The invention according to claim 3 is based on the antireflection film according to claim 2, and the total optical film thickness of the three layers in the three-layer film is 0.25λ 0 to 0.5λ. It is characterized by satisfying the range of 0 .
【００２３】ここで、３層合計の光学的膜厚が設計中心
波長をλ0としたとき０．２５λ0〜０．５λ0の範囲に
設定しているのは、０．２５λ0未満では低反射率の反
射防止膜を形成することが困難な場合があるからであ
り、また、０．５λ0を越えるような厚い膜では反射防
止膜を形成する際の生産性に若干難があり、かつ、形成
された膜の膜厚に分布が生じ易いことから設計値通りの
反射率が得られない場合があるからである。[0023] Here, the optical thickness of the three layers total is set in the range of 0.25λ 0 ~0.5λ 0 when the design center wavelength and lambda 0 is low at less than 0.25 [lambda 0 This is because it may be difficult to form an antireflection film having a reflectance, and if a thick film having a thickness of more than 0.5λ 0 is used, the productivity when forming the antireflection film is slightly difficult, and This is because the film thickness of the formed film is likely to be distributed, so that the reflectance as designed may not be obtained.
【００２４】[0024]
【発明の実施の形態】以下、本発明の実施の形態につい
て詳細に説明する。BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described in detail below.
【００２５】まず、上記数式（２）〜（４）を満たす３
層等価膜膜は、「Thin-film optical filters 2nd ed
n」（ H.A.Macleod著,Bristrol Adam Hilger Ltd. p.11
8-122,1986）に述べられているように、２種類の屈折率
が異なる光学薄膜材料ＡとＢを用いてＡ−Ｂ−Ａまたは
Ｂ−Ａ−Ｂなる３層を形成し、ＡおよびＢの中間的な屈
折率を有する膜とするもので、第１層と第３層の膜厚を
同一としている。First, 3 which satisfies the above equations (2) to (4)
Layer-equivalent film Membrane is the thin-film optical filters 2nd ed
n ”(HAMacleod, Bristrol Adam Hilger Ltd. p.11
8-122, 1986), two kinds of optical thin film materials A and B having different refractive indexes are used to form three layers A-B-A or B-A-B. The film has an intermediate refractive index of B, and the first layer and the third layer have the same film thickness.
【００２６】そして、３層等価膜の反射防止膜は以下の
様に計算される。Then, the antireflection film of the three-layer equivalent film is calculated as follows.
【００２７】まず、磁性ガーネット単結晶の屈折率と媒
質の屈折率とから、単層で反射率がゼロになる理想的な
光学薄膜材料の屈折率ｎfが求められる。First, from the refractive index of the magnetic garnet single crystal and the refractive index of the medium, the ideal refractive index n f of the optical thin film material in which the reflectance is zero in the single layer is obtained.
【００２８】[0028]
【数１４】
ここで、ｎsは磁性ガーネット単結晶の屈折率、ｎ0は媒
質（接着剤）の屈折率である。また、３層等価膜におい
てはｎfは以下の様に表すことができる。[Equation 14] Here, n s is the refractive index of the magnetic garnet single crystal, and n 0 is the refractive index of the medium (adhesive). Further, in the three-layer equivalent film, n f can be expressed as follows.
【００２９】[0029]
【数１５】 [Equation 15]
【００３０】[0030]
【数１６】 [Equation 16]
【００３１】[0031]
【数１７】
但し、σ1＝２πｎ1ｄ1／λ0、σ2＝２πｎ2ｄ2／λ0で
あり、かつ、λ0は設計中心波長、ｎ1は第１層と第３層
の屈折率、ｄ1は第１層と第３層の物理的膜厚、ｎ2は第
２層の屈折率、ｄ2は第２層の物理的膜厚である。[Equation 17] However, σ 1 = 2πn 1 d 1 / λ 0 , σ 2 = 2πn 2 d 2 / λ 0 , and λ 0 is the design center wavelength, n 1 is the refractive index of the first and third layers, and d 1 is the physical thickness of the first and third layers, n 2 is the refractive index of the second layer, and d 2 is the physical thickness of the second layer.
【００３２】そして、第１層と第３層を構成する光学薄
膜材料と第２層を構成する光学薄膜材料が決まれば、上
記数式（１）に基づき磁性ガーネット単結晶の屈折率ｎ
sと媒質（接着剤）の屈折率ｎ0から求められる理想的な
光学薄膜材料の屈折率ｎfから第１層と第３層の物理的
膜厚が求められ、かつ、第１層と第３層の物理的膜厚が
求まれば第２層の物理的膜厚も決定される。Then, if the optical thin film material forming the first and third layers and the optical thin film material forming the second layer are determined, the refractive index n of the magnetic garnet single crystal is determined based on the above equation (1).
The physical film thicknesses of the first and third layers are obtained from the ideal refractive index n f of the optical thin film material obtained from s and the refractive index n 0 of the medium (adhesive), and If the physical film thickness of the three layers is obtained, the physical film thickness of the second layer is also determined.
【００３３】尚、ｎfはｎ1とｎ2の中間的な屈折率であ
るから、ｎ1＜ｎfのときはｎ2＞ｎfである必要があり、
ｎ2＜ｎfのときはｎ1＞ｎfでなければならない。Since n f is an intermediate refractive index between n 1 and n 2 , it is necessary that n 2 > n f when n 1 <n f ,
When n 2 <n f , n 1 > n f must be satisfied.
【００３４】次に、３層膜が上記数式（２）〜（４）を
満たす３層等価膜ではない場合、この反射防止膜は以下
の様に計算される。Next, when the three-layer film is not a three-layer equivalent film satisfying the above equations (2) to (4), this antireflection film is calculated as follows.
【００３５】まず、任意の膜厚の光学薄膜を３層、積層
したときの反射率Ｒは、「Thin-film optical filters
2nd edn」（ H.A.Macleod著,Bristrol Adam Hilger Lt
d.1986）に述べられているように以下のようにして求め
られる。First, the reflectance R when three optical thin films of arbitrary thickness are laminated is shown in "Thin-film optical filters".
2nd edn "(by HAMacleod, Bristrol Adam Hilger Lt
d.1986), it is calculated as follows.
【００３６】[0036]
【数１８】 [Equation 18]
【００３７】[0037]
【数１９】
ここで、σj＝２πｎjｄj／（λ／λ0）、ｉ2＝−１で
あり、λ0は設計中心波長、λは反射率を計算したい波
長、ｄjは第ｊ層の物理的膜厚、ｎjは第ｊ層の屈折率、
ｎsは磁性ガーネット単結晶の屈折率、ｎ0は媒質（接着
剤）の屈折率である。[Formula 19] Here, σ j = 2πn j d j / (λ / λ 0 ), i 2 = −1, λ 0 is the design center wavelength, λ is the wavelength for which the reflectance is to be calculated, and dj is the physical property of the j-th layer. Film thickness, n j is the refractive index of the j-th layer,
n s is the refractive index of the magnetic garnet single crystal, and n 0 is the refractive index of the medium (adhesive).
【００３８】そして、上記の数式（５）〜（６）に基づ
き、各層を構成する光学薄膜材料を決めた後、各層の物
理的膜厚を少しずつ変化させて設計中心波長λ0（例え
ば、１５５０ｎｍ）付近の反射率Ｒがもっとも低くなる
条件を求めることで、反射防止膜が設計される。After determining the optical thin film material forming each layer based on the above equations (5) to (6), the physical film thickness of each layer is changed little by little, and the design center wavelength λ 0 (for example, The antireflection film is designed by obtaining the condition that the reflectance R near 1550 nm) becomes the lowest.
【００３９】ここで、接着剤側の第１層と磁性ガーネッ
ト単結晶側の第３層にＳｉＯ2を選択しているが、これ
は上述したように、ＳｉＯ2が緻密でかつ平滑な膜を形
成するため磁性ガーネット単結晶に対する付着力が高
く、かつ、高い耐候性が得られるからである。Here, SiO 2 is selected for the first layer on the adhesive side and the third layer on the magnetic garnet single crystal side. As described above, this is a film in which SiO 2 is dense and smooth. The reason for this is that since it is formed, it has high adhesion to the magnetic garnet single crystal and high weather resistance.
【００４０】また、本発明においては、第２層にＨｆＯ
2、ＺｒＯ2、Ｔａ2Ｏ5の中から選ばれたいずれか１種を
用いているが、それは以下の理由による。Further, in the present invention, HfO is used as the second layer.
Any one selected from 2 , ZrO 2 and Ta 2 O 5 is used for the following reason.
【００４１】まず、本発明では第１層および第３層にｎ
fより屈折率の小さいＳｉＯ2を用いているため、第２層
としてはｎfより屈折率の大きな光学薄膜材料を用いる
必要がある。尚、第２層にｎfより屈折率の大きな光学
薄膜材料を用いなければならないことは、数式上ｎfが
関係していない数式（５）（６）の場合も同様である。First, in the present invention, the first and third layers are n
Since SiO 2 whose refractive index is smaller than f is used, it is necessary to use an optical thin film material whose refractive index is larger than n f as the second layer. The fact that an optical thin film material having a larger refractive index than n f must be used for the second layer is the same as in the cases of formulas (5) and (6) where n f is not involved in the formula.
【００４２】また、例えＴｉＯ2のようにｎfより屈折率
が大きくても、安定した屈折率の膜を得難く、散乱が多
いと、反射防止膜の特性を損ねてしまう。Further, even if the refractive index is larger than n f , such as TiO 2 , it is difficult to obtain a film having a stable refractive index, and if there is a large amount of scattering, the characteristics of the antireflection film are impaired.
【００４３】そこで、本発明の第２層としては、散乱が
少なく安定した屈折率を有する膜が形成できるＨｆ
Ｏ2、ＺｒＯ2、Ｔａ2Ｏ5を選択している。Therefore, as the second layer of the present invention, Hf capable of forming a film having a stable refractive index with little scattering.
O 2 , ZrO 2 and Ta 2 O 5 are selected.
【００４４】尚、本発明の反射防止膜を形成するには、
真空蒸着法、スパッタ法、イオンプレーティング法など
が適用できるが、低エネルギーのイオンビームを蒸着前
または蒸着中の基板（磁性ガーネット単結晶）に照射
し、電子ビームで蒸着物質を加熱する電子ビームイオン
アシスト蒸着法が、基板（磁性ガーネット単結晶）表面
の清浄化、形成された膜の付着力の向上、充填密度の向
上等に有効であり好適である。In order to form the antireflection film of the present invention,
Although the vacuum deposition method, sputtering method, ion plating method, etc. can be applied, an electron beam that irradiates a substrate (magnetic garnet single crystal) before or during deposition with a low energy ion beam and heats the deposited material with the electron beam The ion-assisted vapor deposition method is effective and suitable for cleaning the surface of the substrate (magnetic garnet single crystal), improving the adhesive force of the formed film, and improving the packing density.
【００４５】[0045]
【実施例】以下、本発明の実施例について具体的に説明
する。EXAMPLES Examples of the present invention will be specifically described below.
【００４６】波長１３１０ｎｍの光に対して屈折率が
２．３５、波長１５５０ｎｍの光に対して屈折率が２．
３４である、組成が（ＹｂＴｂＢｉ）3Ｆｅ5Ｏ12の磁性
ガーネット単結晶を、屈折率が１．５１の接着剤により
偏光子に張り付けて用いる際の反射防止膜を、上述した
方法により計算した。The refractive index is 2.35 for light having a wavelength of 1310 nm and 2.35 for light having a wavelength of 1550 nm.
The antireflection film when a magnetic garnet single crystal having a composition of (YbTbBi) 3 Fe 5 O 12 of 34 was attached to a polarizer with an adhesive having a refractive index of 1.51 was calculated by the method described above. .
【００４７】まず、設計中心波長λ0を１５５０ｎｍと
して、ＳｉＯ2／Ｔａ2Ｏ5／ＳｉＯ2の組み合わせの３層
等価膜（実施例１）、ＳｉＯ2／ＨｆＯ2／ＳｉＯ2の組
み合わせの３層等価膜（実施例２）、ＳｉＯ2／ＺｒＯ2
／ＳｉＯ2の組み合わせの３層等価膜（実施例３）につ
いて計算した。First, with a design center wavelength λ 0 of 1550 nm, a three-layer equivalent film of a combination of SiO 2 / Ta 2 O 5 / SiO 2 (Example 1) and a three-layer of a combination of SiO 2 / HfO 2 / SiO 2 Equivalent film (Example 2), SiO 2 / ZrO 2
Calculation was performed for a three-layer equivalent film (Example 3) of the combination of / SiO 2 .
【００４８】設計値を以下の表１に示す。尚、比較のた
め、従来のＨｆＯ2単層膜による単層反射防止膜の設計
値も表１に示す。The design values are shown in Table 1 below. For comparison, Table 1 also shows design values of a conventional single-layer antireflection film made of a HfO 2 single-layer film.
【００４９】[0049]
【表１】
次に、実施例１〜３および比較例に係る反射防止膜を施
したときの接着剤中での反射率について、その計算値
を、図１（実施例１）、図２（実施例２）、図３（実施
例３）、図４（比較例）に示す。[Table 1] Next, the calculated values of the reflectance in the adhesive when the antireflection films according to Examples 1 to 3 and Comparative Example are applied are shown in FIG. 1 (Example 1) and FIG. 2 (Example 2). 3 (Example 3) and FIG. 4 (Comparative Example).
【００５０】そして、図１〜３に示された分光反射特性
から、実施例１〜３に係る３層等価膜から成る反射防止
膜は全て接着剤に対して非常に良好な反射防止特性を有
していることが確認される。From the spectral reflection characteristics shown in FIGS. 1 to 3, the antireflection films formed of the three-layer equivalent films according to Examples 1 to 3 all have very good antireflection characteristics with respect to the adhesive. It is confirmed that it is doing.
【００５１】次に、３層等価膜でないＳｉＯ2／Ｔａ2Ｏ
5／ＳｉＯ2（実施例４）、ＳｉＯ2／ＨｆＯ2／ＳｉＯ2
（実施例５）、ＳｉＯ2／ＺｒＯ2／ＳｉＯ2（実施例
６）の組み合わせに係る３層反射防止膜を設計した。Next, SiO 2 / Ta 2 O which is not a three-layer equivalent film
5 / SiO 2 (Example 4), SiO 2 / HfO 2 / SiO 2
(Example 5), was designed a three-layer antireflection film according to a combination of SiO 2 / ZrO 2 / SiO 2 ( Example 6).
【００５２】この結果を以下の表２に示す。The results are shown in Table 2 below.
【００５３】[0053]
【表２】
そして、実施例４に係る反射防止膜を施したときの反射
率の計算値を図５に示すが、３層等価膜でない３層反射
防止膜も非常に良好な反射防止特性を有していることが
確認できる。[Table 2] The calculated reflectance of the antireflection film according to Example 4 is shown in FIG. 5. The three-layer antireflection film that is not the three-layer equivalent film also has very good antireflection properties. You can confirm that.
【００５４】次に、本発明に係る反射防止膜の耐候性を
調べるために、電子ビームイオンアシスト蒸着法により
実施例１、実施例４および比較例に係る反射防止膜を成
膜し、その付着力を評価した。Next, in order to examine the weather resistance of the antireflection film according to the present invention, the antireflection films according to Examples 1, 4 and Comparative Example were formed by the electron beam ion assisted vapor deposition method and the coating was applied. The wearing power was evaluated.
【００５５】まず、実施例１と実施例４は以下のように
作製した。First, Example 1 and Example 4 were manufactured as follows.
【００５６】１０ｍｍ角の磁性ガーネット単結晶を蒸着
装置にセットした後、２００℃に加熱しながら３×１０
-4Ｐａまで排気しその状態でＳｉＯ2の蒸着を行った。A 10 mm square magnetic garnet single crystal was set in a vapor deposition apparatus, and then heated at 200 ° C. to 3 × 10 5.
After evacuation to -4 Pa, SiO 2 was vapor-deposited in that state.
【００５７】次に、酸素を１×１０-2Ｐａまで導入し、
Ｔａ2Ｏ5の蒸着を行った。Next, oxygen was introduced up to 1 × 10 -2 Pa,
Deposition of Ta 2 O 5 was performed.
【００５８】そして、酸素の導入を停止してから、再度
ＳｉＯ2の蒸着を行った。イオンアシストにはアルゴン
と酸素の混合ガスを用い、加速電圧８００ｅＶで行っ
た。After the introduction of oxygen was stopped, SiO 2 was vapor-deposited again. A mixed gas of argon and oxygen was used for the ion assist, and the acceleration voltage was 800 eV.
【００５９】一方、比較例に係るＨｆＯ2単層膜は、磁
性ガーネット単結晶を蒸着装置にセットした後、上記実
施例と同様に２００℃に加熱しながら３×１０-4Ｐａま
で排気し、酸素を１×１０-2Ｐａまで導入した後、Ｈｆ
Ｏ2を蒸着した。尚、イオンアシストの条件は実施例と
同様である。On the other hand, in the HfO 2 single layer film according to the comparative example, after the magnetic garnet single crystal was set in the vapor deposition apparatus, it was evacuated to 3 × 10 −4 Pa while being heated to 200 ° C. as in the above example, After introducing oxygen up to 1 × 10 -2 Pa, Hf
O 2 was vapor deposited. The conditions for ion assist are the same as in the embodiment.
【００６０】次に、実施例１、実施例４および比較例に
係る反射防止膜が成膜された各試料を温度８５℃、湿度
８５％の環境に５０００時間放置した後、両方のサンプ
ルの表面を５０倍の顕微鏡で観察したところ、各実施例
の膜には剥離は観察されなかったが、比較例では膜の一
部に剥離が観察された。Next, each sample on which the antireflection film according to Example 1, Example 4 and Comparative Example was formed was allowed to stand for 5000 hours in an environment of a temperature of 85 ° C. and a humidity of 85%. When observed with a microscope of 50 times, peeling was not observed in the film of each example, but peeling was observed in a part of the film in the comparative example.
【００６１】従って、磁性ガーネット単結晶を接着剤に
より偏光子に張り付けて用いる際の反射防止膜について
は、比較例に係る反射防止膜に較べて各実施例に係る反
射防止膜の方が耐候性等に優れていることが確認され
る。Therefore, as for the antireflection film when the magnetic garnet single crystal is attached to the polarizer with the adhesive, the antireflection film according to each example is more weather resistant than the antireflection film according to the comparative example. It is confirmed that they are excellent.
【００６２】次に、実施例１および実施例４に係る試料
を、一般的な耐久試験条件より厳しい条件である、温度
８５℃、湿度９８％の環境に１０００時間放置したとこ
ろ、実施例１に係る反射防止膜には白濁が観察された
が、実施例４に係る反射防止膜には変化が見られず、よ
り強い耐候性を有していることが確認された。Next, the samples according to Examples 1 and 4 were allowed to stand for 1000 hours in an environment of temperature 85 ° C. and humidity 98%, which is more severe than general durability test conditions. Although white turbidity was observed in the antireflection film, no change was observed in the antireflection film according to Example 4, and it was confirmed that the antireflection film had stronger weather resistance.
【００６３】[0063]
【発明の効果】請求項１記載の発明に係る反射防止膜に
よれば、第１層と第３層について緻密な膜が形成可能な
ＳｉＯ2を適用することで強い付着力、耐候性が確保さ
れ、第２層についてＨｆＯ2、ＺｒＯ2、Ｔａ2Ｏ5の中か
ら選ばれたいずれか１種を適用することで３層という比
較的少ない層数で低反射率が達成され、更に、上記数式
（２）〜（４）を満たす３層等価膜とすることで第１層
と第３層の膜厚を同じに設定できその成膜が容易となる
効果を有する。According to the antireflection film of the first aspect of the present invention, strong adhesion and weather resistance are secured by applying SiO 2 capable of forming a dense film to the first layer and the third layer. By applying any one selected from HfO 2 , ZrO 2 , and Ta 2 O 5 to the second layer, a low reflectance is achieved with a relatively small number of layers of 3 and further, The three-layer equivalent film satisfying the mathematical expressions (2) to (4) has the effect that the film thicknesses of the first layer and the third layer can be set to be the same and the film formation thereof can be facilitated.
【００６４】次に、請求項２〜３記載の発明に係る反射
防止膜によれば、接着剤側の第１層が緻密な膜を形成可
能なＳｉＯ2で構成されかつその物理的膜厚が２００ｎ
ｍ以上と厚いため、請求項１記載の発明に係る反射防止
膜の上記効果に加えて耐候性により優れている効果を有
する。Next, according to the antireflection film of the invention described in claims 2 to 3, the first layer on the adhesive side is composed of SiO 2 capable of forming a dense film, and its physical film thickness is 200n
Since it is thicker than m, in addition to the above effect of the antireflection film according to the invention of claim 1, it has an effect of being more excellent in weather resistance.
【図１】図１（Ａ）は実施例１に係るＳｉＯ2／Ｔａ2Ｏ
5／ＳｉＯ2３層等価膜の分光反射率特性を示す図表、図
１（Ｂ）は媒質、各層、基板（磁性ガーネット単結晶）
の屈折率等を示す図表、図１（Ｃ）は上記３層等価膜の
分光反射率特性を示すグラフ図。FIG. 1A is SiO 2 / Ta 2 O according to Example 1.
Chart showing spectral reflectance characteristics of 5 / SiO 2 three-layer equivalent film, FIG. 1 (B) shows medium, each layer, substrate (magnetic garnet single crystal)
FIG. 1C is a graph showing the spectral reflectance characteristics of the above three-layer equivalent film.
【図２】図２（Ａ）は実施例２に係るＳｉＯ2／ＨｆＯ2
／ＳｉＯ2３層等価膜の分光反射率特性を示す図表、図
２（Ｂ）は媒質、各層、基板（磁性ガーネット単結晶）
の屈折率等を示す図表、図２（Ｃ）は上記３層等価膜の
分光反射率特性を示すグラフ図。FIG. 2A is a SiO 2 / HfO 2 film according to Example 2.
/ SiO 2 A diagram showing the spectral reflectance characteristics of a three-layer equivalent film, FIG. 2B shows a medium, each layer, and a substrate (magnetic garnet single crystal)
FIG. 2C is a graph showing the spectral reflectance characteristics of the above three-layer equivalent film.
【図３】図３（Ａ）は実施例３に係るＳｉＯ2／ＺｒＯ2
／ＳｉＯ2３層等価膜の分光反射率特性を示す図表、図
３（Ｂ）は媒質、各層、基板（磁性ガーネット単結晶）
の屈折率等を示す図表、図３（Ｃ）は上記３層等価膜の
分光反射率特性を示すグラフ図。FIG. 3A is SiO 2 / ZrO 2 according to Example 3;
/ SiO 2 chart showing spectral reflectance characteristics of a three-layer equivalent film, FIG. 3B shows a medium, each layer, a substrate (magnetic garnet single crystal)
And FIG. 3C is a graph showing the spectral reflectance characteristics of the three-layer equivalent film.
【図４】図４（Ａ）は比較例に係るＨｆＯ2単層反射防
止膜の分光反射率特性を示す図表、図４（Ｂ）は媒質、
第１層、基板（磁性ガーネット単結晶）の屈折率等を示
す図表、図４（Ｃ）は上記単層反射防止膜の分光反射率
特性を示すグラフ図。FIG. 4 (A) is a chart showing the spectral reflectance characteristics of a HfO 2 single-layer antireflection film according to a comparative example, FIG. 4 (B) is a medium,
The first layer, a table showing the refractive index of the substrate (magnetic garnet single crystal), and FIG. 4C is a graph showing the spectral reflectance characteristics of the single-layer antireflection film.
【図５】図５（Ａ）は実施例４に係るＳｉＯ2／Ｔａ2Ｏ
5／ＳｉＯ2３層等価膜でない３層反射防止膜の分光反射
率特性の分光反射率特性を示す図表、図５（Ｂ）は媒
質、各層、基板（磁性ガーネット単結晶）の屈折率等を
示す図表、図５（Ｃ）は上記３層反射防止膜の分光反射
率特性を示すグラフ図。FIG. 5 (A) is SiO 2 / Ta 2 O according to Example 4.
5 / SiO 2 A diagram showing the spectral reflectance characteristics of the three-layer antireflection film that is not a three-layer equivalent film, and FIG. 5B shows the refractive index of the medium, each layer, the substrate (magnetic garnet single crystal), etc. FIG. 5C is a graph showing the spectral reflectance characteristics of the above three-layer antireflection film.
───────────────────────────────────────────────────── フロントページの続き Ｆターム(参考） 2H049 BA02 BA08 BA42 BB51 BB65 BC14 BC25 2H079 AA03 BA02 DA13 DA27 EA27 HA21 2K009 AA06 BB04 CC03 DD03 DD07 DD08 FF03 ─────────────────────────────────────────────────── ─── Continued front page F term (reference) 2H049 BA02 BA08 BA42 BB51 BB65 BC14 BC25 2H079 AA03 BA02 DA13 DA27 EA27 HA21 2K009 AA06 BB04 CC03 DD03 DD07 DD08 FF03
Claims (3)
て使用される磁性ガーネット単結晶から成るファラデー
回転子の反射防止膜において、 接着剤側の第１層と磁性ガーネット単結晶側の第３層が
ＳｉＯ2で、第１層と第３層に挟まれた第２層がＨｆ
Ｏ2、ＺｒＯ2、Ｔａ2Ｏ5の中から選ばれたいずれか１種
であると共に、下記数式（２）〜（４）を満たす３層等
価膜により構成されることを特徴とするファラデー回転
子用反射防止膜。 【数１】 【数２】 【数３】 但し、σ1＝２πｎ1ｄ1／λ0、σ2＝２πｎ2ｄ2／λ0、
ｎ1＜ｎf＜ｎ2であり、かつ、ｎfは磁性ガーネット単結
晶の屈折率をｎs、接着剤の屈折率をｎ0とした場合に下
記数式（１）から求まる単層で反射率が０になる光学薄
膜材料の屈折率、ｎ1は第１層と第３層の屈折率、ｄ1は
第１層と第３層の物理的膜厚、ｎ2は第２層の屈折率、
ｄ2は第２層の物理的膜厚、λ0は設計中心波長である。 【数４】 1. An antireflection film for a Faraday rotator made of a magnetic garnet single crystal, which is used by being bonded to an optical component via an optical adhesive, comprising a first layer on the adhesive side and a third layer on the magnetic garnet single crystal side. The layer is SiO 2 and the second layer sandwiched between the first layer and the third layer is Hf
Faraday rotation characterized by being composed of a three-layer equivalent film which is any one selected from O 2 , ZrO 2 , and Ta 2 O 5 and which satisfies the following formulas (2) to (4). Anti-reflection film for child. [Equation 1] [Equation 2] [Equation 3] However, σ 1 = 2πn 1 d 1 / λ 0 , σ 2 = 2πn 2 d 2 / λ 0 ,
n 1 <n f <n 2 and n f is reflected by a single layer obtained from the following formula (1) when the refractive index of the magnetic garnet single crystal is n s and the refractive index of the adhesive is n 0. Refractive index of the optical thin film material whose index becomes 0, n 1 is the refractive index of the first and third layers, d 1 is the physical film thickness of the first and third layers, n 2 is the refractive index of the second layer rate,
d 2 is the physical film thickness of the second layer, and λ 0 is the design center wavelength. [Equation 4]
て使用される磁性ガーネット単結晶から成るファラデー
回転子の反射防止膜において、 接着剤側の第１層と磁性ガーネット単結晶側の第３層が
ＳｉＯ2で、第１層と第３層に挟まれた第２層がＨｆ
Ｏ2、ＺｒＯ2、Ｔａ2Ｏ5の中から選ばれたいずれか１種
であると共に、下記数式（５）〜（６）から求まる設計
中心波長λ0付近の反射率Ｒが最も低くなる条件を満た
した３層膜により構成され、かつ、第１層であるＳｉＯ
2の物理的膜厚が２００ｎｍ以上であることを特徴とす
るファラデー回転子用反射防止膜。 【数５】 【数６】 但し、σj＝２πｎjｄj／（λ／λ0）、ｉ2＝−１であ
り、かつ、λは反射率Ｒを計算したい波長、ｄjは第ｊ
層の物理的膜厚、ｎjは第ｊ層の屈折率、ｎsは磁性ガー
ネット単結晶の屈折率、ｎ0は接着剤の屈折率である。2. An antireflection film for a Faraday rotator made of a magnetic garnet single crystal, which is used by being bonded to an optical component via an optical adhesive, wherein a first layer on the adhesive side and a third layer on the magnetic garnet single crystal side are used. The layer is SiO 2 and the second layer sandwiched between the first layer and the third layer is Hf
A condition that the reflectance R is the lowest in the vicinity of the design center wavelength λ 0 , which is any one selected from O 2 , ZrO 2 , and Ta 2 O 5 and is obtained from the following formulas (5) to (6). Which is a first layer composed of a three-layer film that satisfies
2. An antireflection film for a Faraday rotator, wherein the physical film thickness of 2 is 200 nm or more. [Equation 5] [Equation 6] However, σ j = 2πn j dj / (λ / λ 0 ), i 2 = −1, λ is the wavelength for which the reflectance R is to be calculated, and dj is the j-th wavelength.
The physical thickness of the layer, n j is the refractive index of the j-th layer, n s is the refractive index of the magnetic garnet single crystal, and n 0 is the refractive index of the adhesive.
が０．２５λ0〜０．５λ0の範囲を満たしていることを
特徴とする請求項２記載のファラデー回転子用反射防止
膜。3. The antireflection for a Faraday rotator according to claim 2, wherein the total optical thickness of the three layers in the three-layer film satisfies the range of 0.25λ 0 to 0.5λ 0. film.
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| Application Number | Priority Date | Filing Date | Title |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007143353A1 (en) * | 2006-05-31 | 2007-12-13 | Hewlett-Packard Development Company, L.P. | Structure and method for optical coating |
-
2001
- 2001-08-21 JP JP2001250857A patent/JP2003057404A/en active Pending
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2007143353A1 (en) * | 2006-05-31 | 2007-12-13 | Hewlett-Packard Development Company, L.P. | Structure and method for optical coating |
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