JP4136744B2 - Reflective film - Google Patents
Reflective film Download PDFInfo
- Publication number
- JP4136744B2 JP4136744B2 JP2003081382A JP2003081382A JP4136744B2 JP 4136744 B2 JP4136744 B2 JP 4136744B2 JP 2003081382 A JP2003081382 A JP 2003081382A JP 2003081382 A JP2003081382 A JP 2003081382A JP 4136744 B2 JP4136744 B2 JP 4136744B2
- Authority
- JP
- Japan
- Prior art keywords
- refractive index
- laser
- yag
- reflective film
- film
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Images
Landscapes
- Optical Elements Other Than Lenses (AREA)
- Optical Filters (AREA)
- Physical Vapour Deposition (AREA)
Description
【０００１】
【発明の属する技術分野】
本発明は、光学薄膜により構成され、例えば、レーザ共振器、レーザ反射鏡、レーザ素子等の部品に適用される反射膜に係り、特に、膜設計の自由度を広げると共に耐レーザ損傷性に優れた反射膜の改良に関するものである。
【０００２】
【従来の技術】
光学薄膜により構成されるこの種の反射膜は、従来、以下の表１に示す代表的な膜材料を用いて構成されている。
【０００３】
【表１】
【０００４】
そして、反射膜の設計中心波長λにおける反射率は、低屈折率層と高屈折率層の屈折率差と膜総数によって決定される。すなわち、この屈折率差が大きく、膜総数が多い反射膜ほど設計中心波長λにおける反射率は高くなる。
【０００５】
以下、低屈折率層としてＳｉＯ2、高屈折率層としてＴａ2Ｏ5を用い、表２に示すように高屈折率層と低屈折率層を交互に２３層積層して成る従来例に係る反射膜の分光反射特性を図１に示す。
【０００６】
そして、図１のグラフ図から確認されるように、設計中心波長（λ＝１０６４ｎｍ）における反射率は、９９．９６％に達する。
【０００７】
【表２】
【発明が解決しようとする課題】
ところで、高屈折率層と低屈折率層を交互に積層して構成される反射膜の設計中心波長λにおける反射率は、上述したように低屈折率層と高屈折率層の屈折率差と膜総数によって決定され、この屈折率差が大きく、膜総数が多い反射膜ほど設計中心波長λにおける反射率は高くなる。従って、屈折率差が大きい少なくとも２種類以上の膜材料を適用することで膜総数を減らすことも可能である。
【０００９】
しかしながら、高出力レーザに適用する反射膜については、膜総数を減らすために屈折率差の大きい膜材料を選択することは望ましくない。
【００１０】
例えば、可視域から近赤外域のレーザ反射鏡の低屈折率層にはレーザ損傷閾値が高いＳｉＯ2を用いることが一般的であり、高屈折率層には、屈折率が高い順にＴｉＯ2、Ｔａ2Ｏ5、ＺｒＯ2を用いる場合が多い。しかし、この屈折率が高い順にレーザ損傷閾値が低い欠点があった。
【００１１】
従って、レーザ損傷閾値が低い膜材料を用いて反射膜を構成した場合、高出力レーザにより反射膜がダメージを受けて、反射膜のみならず、反射膜が施されている素子そのものまでがダメージを受けて、その機器の本来の性能が発揮されなくなる問題点があった。
【００１２】
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、反射膜に適用できる新規な膜材料を提供して膜設計の自由度を広げると共に耐レーザ損傷性に優れた反射膜を提供することにある。
【００１３】
【課題を解決するための手段】
すなわち、請求項１に係る発明は、
高屈折率層と低屈折率層を交互に積層して構成される反射膜を前提とし、
上記高屈折率層がＹＡＧ（Ｙ3Ａｌ5Ｏ12：イットリウムアルミニウムガーネット）で構成されていることを特徴とし、
請求項２に係る発明は、
請求項１記載の発明に係る反射膜を前提とし、
レーザ共振器、レーザ反射鏡またはレーザ素子のいずれかに施されることを特徴とするものである。
【００１４】
【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。
【００１５】
本発明は、高屈折率層と低屈折率層を交互に積層して構成される反射膜の上記高屈折率層の光学薄膜材料として、ＹＡＧ（Ｙ3Ａｌ5Ｏ12：イットリウムアルミニウムガーネット）を新たに追加することで膜設計の自由度を広げると共に耐レーザ損傷性の向上を可能としている。
【００１６】
すなわち、ＹＡＧ（Ｙ3Ａｌ5Ｏ12：イットリウムアルミニウムガーネット）はレーザ結晶として知られているように非常に硬度が高く、熱伝導率もよく、化学的にも安定で、透過波長域も約２５０〜５０００ｎｍと広く、さらに、光吸収も非常に少なく、耐レーザ損傷性も高いことから、本発明者等はＹＡＧのこれ等特性に着目して反射膜への応用を試み、上記課題を解決している。
【００１７】
そして、上述したＴｉＯ2、Ｔａ2Ｏ5、ＺｒＯ2に代えてＹＡＧを適用し、低屈折率層としてのＳｉＯ2と組み合わせることにより耐レーザ損傷性に優れた反射膜の提供を可能にしている。
【００１８】
但し、ＹＡＧの屈折率は１．８０で、高出力レーザ用反射鏡の高屈折率層に用いられるＴａ2Ｏ5の屈折率２．１０より小さいため、ＳｉＯ2とＴａ2Ｏ5で構成した上記２３層の反射鏡と同じ反射率９９．９６％とするにはＳｉＯ2とＹＡＧを交互に３９層以上積層する必要があるが、現在の成膜技術において３９層程度の蒸着は困難なことではない。
【００１９】
尚、ＹＡＧ（Ｙ3Ａｌ5Ｏ12：イットリウムアルミニウムガーネット）で構成される高屈折率層については、ＹＡＧ（Ｙ3Ａｌ5Ｏ12：イットリウムアルミニウムガーネット）の結晶体若しくは焼結体、または酸素欠損を有するＹＡＧ（Ｙ3Ａｌ5Ｏ12-X）の結晶体若しくは焼結体を蒸着材料若しくはスパッタターゲットとして成膜してもよいし、あるいは、Ｙ2Ｏ3（イットリア）とＡｌ2Ｏ3（アルミナ）の結晶体若しくは焼結体、または酸素欠損を有するイットリア（Ｙ2Ｏ3-X）と酸素欠損を有するアルミナ（Ａｌ2Ｏ3-X）の結晶体若しくは焼結体を蒸着材料若しくはスパッタターゲットとして成膜してもよい。
【００２０】
以下、ＹＡＧ（Ｙ3Ａｌ5Ｏ12：イットリウムアルミニウムガーネット）で構成される高屈折率層が適用された本発明に係る反射膜について具体的に説明する。
【００２１】
すなわち、高屈折率層にＹＡＧを用い、低屈折率層にＳｉＯ2を用いた３９層の本発明に係る反射膜の構成を表３〜表４に示し、かつ、この反射膜における分光反射特性を図２に示す。
【００２２】
【表３】
【表４】
【実施例】
以下、本発明の実施例について比較例を挙げて具体的に説明する。
【００２５】
まず、高屈折率層にＴａ2Ｏ5を用いた表２に示す比較例に係るＮｄ：ＹＡＧレーザ反射鏡（設計中心波長λ＝１０６４ｎｍ）と、高屈折率層にＹＡＧを用いた表３〜４に示す実施例に係るＮｄ：ＹＡＧレーザ反射鏡（設計中心波長λ＝１０６４ｎｍ）を実際に作製し、各Ｎｄ：ＹＡＧレーザ反射鏡の耐レーザ損傷性を比較した。
【００２６】
尚、実施例および比較例に係るＮｄ：ＹＡＧレーザ反射鏡の作製には、イオンアシスト電子ビーム蒸着法を用い、かつ、基板ガラスＢＫ７を２００℃に加熱し、成膜中には酸素を導入した。
【００２７】
そして、各Ｎｄ：ＹＡＧレーザ反射鏡の耐レーザ損傷性を比較するため、発振波長１０６４ｎｍ、パルス幅１０ｎｓのＮｄ：ＹＡＧレーザをレンズを用いて集光させ、そのパワー密度（Ｊ/ｃｍ2）により損傷を受けるか受けないかを調べるレーザ損傷テストを各Ｎｄ：ＹＡＧレーザ反射鏡に対し実施した。
【００２８】
その結果、実施例に係るＮｄ：ＹＡＧレーザ反射鏡のレーザ損傷閾値は２０（Ｊ/ｃｍ2）、比較例に係るＮｄ：ＹＡＧレーザ反射鏡のレーザ損傷閾値は１４（Ｊ/ｃｍ2）であった。
【００２９】
そして、ＳｉＯ2のレーザ損傷閾値は非常に高いので、実施例に係るＮｄ：ＹＡＧレーザ反射鏡のレーザ損傷閾値が、比較例に係るＮｄ：ＹＡＧレーザ反射鏡のレーザ損傷閾値より高い原因は、高屈折率層に用いているＴａ2Ｏ5とＹＡＧにおけるレーザ損傷閾値の差が反映しているものと考えられる。
【００３０】
【発明の効果】
高屈折率層と低屈折率層を交互に積層して構成される本発明に係る反射膜によれば、
上記高屈折率層がＹＡＧ（Ｙ3Ａｌ5Ｏ12：イットリウムアルミニウムガーネット）で構成されているため以下のような顕著な効果を有する。
【００３１】
まず、ＹＡＧの屈折率を利用して新たな反射膜の設計が可能となり、かつ、ＹＡＧの光学薄膜が具備する耐候性、硬度、付着力等の特性を生かして今までにない特性を有した反射膜を得ることが可能となる効果を有する。
【００３２】
さらに、ＹＡＧの光学薄膜は耐レーザ損傷性にも優れているので、ＳｉＯ2等と組み合わせることにより、耐レーザ損傷性に優れた反射膜を得ることができる効果を有する。
【図面の簡単な説明】
【図１】従来例に係る反射膜の分光反射特性を示すグラフ図。
【図２】本発明に係る反射膜の分光反射特性を示すグラフ図。[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a reflective film that is composed of an optical thin film and is applied to components such as a laser resonator, a laser reflector, and a laser element, and in particular, it increases the degree of freedom in film design and is excellent in laser damage resistance. The present invention relates to an improvement of a reflective film.
[0002]
[Prior art]
Conventionally, this type of reflective film constituted by an optical thin film is constituted by using typical film materials shown in Table 1 below.
[0003]
[Table 1]
[0004]
The reflectance at the design center wavelength λ of the reflective film is determined by the refractive index difference between the low refractive index layer and the high refractive index layer and the total number of films. That is, the reflectance at the design center wavelength λ becomes higher as the reflective film has a larger refractive index difference and a larger total number of films.
[0005]
Hereinafter, SiO 2 is used as the low refractive index layer, Ta 2 O 5 is used as the high refractive index layer, and as shown in Table 2, according to the conventional example in which 23 layers of high refractive index layers and low refractive index layers are alternately stacked. The spectral reflection characteristics of the reflective film are shown in FIG.
[0006]
As confirmed from the graph of FIG. 1, the reflectance at the design center wavelength (λ = 1064 nm) reaches 99.96%.
[0007]
[Table 2]
[Problems to be solved by the invention]
By the way, as described above, the reflectance at the design center wavelength λ of the reflection film formed by alternately stacking the high refractive index layer and the low refractive index layer is the difference in refractive index between the low refractive index layer and the high refractive index layer. The reflection film is determined by the total number of films, and the refractive index difference is large, and the reflection film having a large number of films has a higher reflectance at the design center wavelength λ. Accordingly, it is possible to reduce the total number of films by applying at least two kinds of film materials having a large difference in refractive index.
[0009]
However, for a reflective film applied to a high-power laser, it is not desirable to select a film material having a large refractive index difference in order to reduce the total number of films.
[0010]
For example, it is common to use SiO 2 having a high laser damage threshold for the low refractive index layer of the laser reflector in the visible region to the near infrared region, and for the high refractive index layer, TiO 2 in order of increasing refractive index, Ta 2 O 5 and ZrO 2 are often used. However, there is a defect that the laser damage threshold is low in the descending order of the refractive index.
[0011]
Therefore, when the reflective film is formed using a film material having a low laser damage threshold, the reflective film is damaged by the high-power laser, and not only the reflective film but also the element itself with the reflective film is damaged. As a result, there was a problem that the original performance of the device could not be demonstrated.
[0012]
The present invention has been made paying attention to such problems, and the object of the present invention is to provide a novel film material that can be applied to a reflective film to increase the degree of freedom in film design and to improve laser damage resistance. The object is to provide an excellent reflective film.
[0013]
[Means for Solving the Problems]
That is, the invention according to claim 1
Assuming a reflective film composed of alternating high and low refractive index layers ,
The high refractive index layer is YAG: characterized by being composed by (Y 3 Al 5 O 12, yttrium aluminum garnet),
The invention according to claim 2
On the premise of the reflective film according to the invention of claim 1,
It is applied to any one of a laser resonator, a laser reflecting mirror, and a laser element.
[0014]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in detail.
[0015]
In the present invention, YAG (Y 3 Al 5 O 12 : yttrium aluminum garnet) is used as an optical thin film material of the high refractive index layer of the reflective film constituted by alternately laminating high refractive index layers and low refractive index layers. The new addition increases the degree of freedom in film design and improves the laser damage resistance.
[0016]
That is, YAG (Y 3 Al 5 O 12 : yttrium aluminum garnet) is known as a laser crystal and has very high hardness, good thermal conductivity, chemical stability, and a transmission wavelength range of about 250. Since it is as wide as ˜5000 nm, light absorption is very low, and laser damage resistance is high, the present inventors have tried to apply to a reflective film by paying attention to these characteristics of YAG, and solved the above problems. ing.
[0017]
Then, instead of TiO 2 , Ta 2 O 5 , and ZrO 2 described above, YAG is applied and combined with SiO 2 as a low refractive index layer, it is possible to provide a reflective film having excellent laser damage resistance. .
[0018]
However, since the refractive index of YAG is 1.80, which is smaller than the refractive index of Ta 2 O 5 used for the high refractive index layer of the high-power laser reflector, it is composed of SiO 2 and Ta 2 O 5 . In order to obtain the same reflectivity of 99.96% as the above-mentioned 23-layer reflector, it is necessary to alternately stack 39 or more layers of SiO 2 and YAG. However, it is difficult to deposit about 39 layers with the current film formation technology. is not.
[0019]
Incidentally, YAG: for high refractive index layer composed of (Y 3 Al 5 O 12, yttrium aluminum garnet), YAG: crystal or sintered body of (Y 3 Al 5 O 12, yttrium aluminum garnet) or oxygen deficiency, A YAG (Y 3 Al 5 O 12-X ) crystal or sintered body having the following may be formed as a deposition material or a sputtering target, or Y 2 O 3 (yttria) and Al 2 O 3 ( Alumina) crystals or sintered bodies, or oxygen deficient yttria (Y 2 O 3−X ) and oxygen deficient alumina (Al 2 O 3−X ) crystals or sintered bodies are used as vapor deposition materials or sputtering. A film may be formed as a target.
[0020]
Hereinafter, the reflective film according to the present invention to which the high refractive index layer composed of YAG (Y 3 Al 5 O 12 : yttrium aluminum garnet) is applied will be described in detail.
[0021]
That is, Tables 3 to 4 show the configurations of 39 reflective films according to the present invention using YAG for the high refractive index layer and SiO 2 for the low refractive index layer, and the spectral reflection characteristics in this reflective film. Is shown in FIG.
[0022]
[Table 3]
[Table 4]
【Example】
Examples of the present invention will be specifically described below with reference to comparative examples.
[0025]
First, an Nd: YAG laser reflector (design center wavelength λ = 1064 nm) according to a comparative example shown in Table 2 using Ta 2 O 5 for the high refractive index layer, and Table 3 using YAG for the high refractive index layer. Nd: YAG laser reflectors (design center wavelength λ = 1064 nm) according to the example shown in FIG. 4 were actually fabricated, and the laser damage resistance of each Nd: YAG laser reflector was compared.
[0026]
The Nd: YAG laser reflecting mirror according to the example and the comparative example was manufactured by using an ion-assisted electron beam evaporation method, the substrate glass BK7 was heated to 200 ° C., and oxygen was introduced during the film formation. .
[0027]
In order to compare the laser damage resistance of each Nd: YAG laser reflecting mirror, an Nd: YAG laser having an oscillation wavelength of 1064 nm and a pulse width of 10 ns is condensed using a lens, and the power density (J / cm 2 ) A laser damage test was conducted on each Nd: YAG laser reflector to see if it was damaged or not.
[0028]
As a result, the laser damage threshold of the Nd: YAG laser reflector according to the example was 20 (J / cm 2 ), and the laser damage threshold of the Nd: YAG laser reflector according to the comparative example was 14 (J / cm 2 ). It was.
[0029]
Since the laser damage threshold of SiO 2 is very high, the cause of the laser damage threshold of the Nd: YAG laser reflector according to the embodiment being higher than the laser damage threshold of the Nd: YAG laser reflector according to the comparative example is high. This is considered to reflect the difference in laser damage threshold between Ta 2 O 5 and YAG used in the refractive index layer.
[0030]
【The invention's effect】
According to the reflective film according to the present invention configured by alternately laminating high refractive index layers and low refractive index layers ,
Since the high refractive index layer is composed of YAG (Y 3 Al 5 O 12 : yttrium aluminum garnet) , it has the following remarkable effects.
[0031]
First, it became possible to design a new reflective film using the refractive index of YAG, and it had characteristics that were not available by taking advantage of the characteristics such as weather resistance, hardness, adhesion, etc. possessed by the optical thin film of YAG. It has an effect that a reflective film can be obtained.
[0032]
Furthermore, since the optical thin film of YAG is also excellent in laser damage resistance, when combined with SiO 2 or the like, there is an effect that a reflection film excellent in laser damage resistance can be obtained.
[Brief description of the drawings]
FIG. 1 is a graph showing spectral reflection characteristics of a reflection film according to a conventional example.
FIG. 2 is a graph showing spectral reflection characteristics of a reflective film according to the present invention.
Claims (2)
上記高屈折率層がＹＡＧ（Ｙ3Ａｌ5Ｏ12：イットリウムアルミニウムガーネット）で構成されていることを特徴とする反射膜。 In a reflective film configured by alternately laminating high refractive index layers and low refractive index layers ,
The high refractive index layer is YAG: reflective film, which is composed of (Y 3 Al 5 O 12, yttrium aluminum garnet).
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003081382A JP4136744B2 (en) | 2003-03-24 | 2003-03-24 | Reflective film |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2003081382A JP4136744B2 (en) | 2003-03-24 | 2003-03-24 | Reflective film |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| JP2004287273A JP2004287273A (en) | 2004-10-14 |
| JP2004287273A5 JP2004287273A5 (en) | 2005-10-06 |
| JP4136744B2 true JP4136744B2 (en) | 2008-08-20 |
Family
ID=33294967
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2003081382A Expired - Fee Related JP4136744B2 (en) | 2003-03-24 | 2003-03-24 | Reflective film |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP4136744B2 (en) |
Families Citing this family (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN1308715C (en) * | 2004-11-26 | 2007-04-04 | 中国科学院上海光学精密机械研究所 | Preparation of Yb-Gd-Ga doped garnet planar optical waveguide |
| JP5975461B2 (en) * | 2012-02-03 | 2016-08-23 | 大学共同利用機関法人 高エネルギー加速器研究機構 | Laser Compton scattering device |
| CN112266571A (en) * | 2020-10-26 | 2021-01-26 | 东莞市鑫聚光电科技股份有限公司 | PDLC light modulation film |
-
2003
- 2003-03-24 JP JP2003081382A patent/JP4136744B2/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| JP2004287273A (en) | 2004-10-14 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US5850309A (en) | Mirror for high-intensity ultraviolet light beam | |
| JP2629693B2 (en) | Excimer laser mirror | |
| US6894838B2 (en) | Extended bandwidth mirror | |
| JP3332879B2 (en) | Dichroic mirror | |
| JP3799696B2 (en) | Mirror for excimer laser | |
| JP2691651B2 (en) | Reflector | |
| JP4136744B2 (en) | Reflective film | |
| JPH11202127A (en) | Dichroic mirror | |
| JP2005031298A (en) | Transparent substrate with antireflection film | |
| JPS61182288A (en) | Gas laser | |
| JP2009031406A (en) | Nonpolarization beam splitter and optical measuring instrument using the same | |
| JP2748066B2 (en) | Reflector | |
| JP2003101126A (en) | Semiconductor laser device and method of manufacturing the same | |
| JP2001074903A (en) | Antireflection film and optical device | |
| JP3276182B2 (en) | Surface reflector | |
| JPH11101903A (en) | High reflection mirror for excimer laser | |
| JP3084784B2 (en) | Argon gas laser mirror | |
| JP2007003936A (en) | Infrared region reflecting mirror and its manufacturing method | |
| JP4177147B2 (en) | 3-layer antireflection coating | |
| JP3560638B2 (en) | Reflective film | |
| JPH04145677A (en) | High efficiency reflector for visible laser beam | |
| JP4177146B2 (en) | Two-layer antireflection film | |
| JP2928784B2 (en) | Multilayer reflector | |
| JPH0763907A (en) | Reflection mirror for laser | |
| JPH09265005A (en) | Mirror for excimer laser |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20050524 |
|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20050524 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20080215 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20080226 |
|
| A521 | Written amendment |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20080424 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20080521 |
|
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20080603 |
|
| R150 | Certificate of patent or registration of utility model |
Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20110613 Year of fee payment: 3 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20120613 Year of fee payment: 4 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20130613 Year of fee payment: 5 |
|
| FPAY | Renewal fee payment (event date is renewal date of database) |
Free format text: PAYMENT UNTIL: 20140613 Year of fee payment: 6 |
|
| LAPS | Cancellation because of no payment of annual fees |