JPH01172902A - Diffraction grating - Google Patents
Diffraction gratingInfo
- Publication number
- JPH01172902A JPH01172902A JP62331978A JP33197887A JPH01172902A JP H01172902 A JPH01172902 A JP H01172902A JP 62331978 A JP62331978 A JP 62331978A JP 33197887 A JP33197887 A JP 33197887A JP H01172902 A JPH01172902 A JP H01172902A
- Authority
- JP
- Japan
- Prior art keywords
- diffraction grating
- photosensitive layer
- grating
- curve
- diffraction
- 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.)
- Pending
Links
Classifications
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/18—Diffraction gratings
- G02B5/1847—Manufacturing methods
- G02B5/1857—Manufacturing methods using exposure or etching means, e.g. holography, photolithography, exposure to electron or ion beams
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/18—Diffraction gratings
- G02B5/1861—Reflection gratings characterised by their structure, e.g. step profile, contours of substrate or grooves, pitch variations, materials
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Optics & Photonics (AREA)
- Engineering & Computer Science (AREA)
- Manufacturing & Machinery (AREA)
- Diffracting Gratings Or Hologram Optical Elements (AREA)
Abstract
(57)【要約】本公報は電子出願前の出願データであるた
め要約のデータは記録されません。(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.
Description
【発明の詳細な説明】
産業上の利用分野
本発明は、分光器、光通信デバイス等に用いる回折格子
に関するものである。DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a diffraction grating used in spectrometers, optical communication devices, and the like.
従来の技術
近年、回折格子は良好な波長選択性を有し、高分解能な
光部品であるため多くの光デバイスへの利用が試みられ
ている。その中でもホログラフィク露光によって作製す
る回折格子はその製作工程が機械切り格子に比べ簡単で
安価にできるうえに、露光する干渉縞間隔が一定である
ので迷光が少ない点で有利であるが、回折効率は一般に
ホログラフィク露光で作製した回折格子は低く、高効率
化への努力が続けられている。BACKGROUND OF THE INVENTION In recent years, diffraction gratings have good wavelength selectivity and are high-resolution optical components, so attempts have been made to use them in many optical devices. Among these, diffraction gratings made by holographic exposure have the advantage of being easier and cheaper to manufacture than mechanically cut gratings, and have the advantage of less stray light because the exposed interference fringe spacing is constant. Diffraction gratings made by holographic exposure generally have low diffraction gratings, and efforts are being made to improve their efficiency.
以下、図面を参照しながら、従来の回折格子の一例につ
いて説明する。An example of a conventional diffraction grating will be described below with reference to the drawings.
第４図は従来の回折格子の断面形状を表した図である。FIG. 4 is a diagram showing the cross-sectional shape of a conventional diffraction grating.
４１は反射膜、４２は感光性材料よりなる感光層、４３
は基板である。41 is a reflective film, 42 is a photosensitive layer made of a photosensitive material, 43
is the substrate.
第５図は、第４図は回折格子のうちポジ型の感光性材料
よりなる感光層の感度曲線を表した図である。横軸は露
光量、縦軸は現像後の感光層膜厚の残存膜厚率、５１は
露光干渉縞の強度分布、５２は現像後の格子断面形状、
５３は感度曲線である。FIG. 5 is a diagram showing a sensitivity curve of a photosensitive layer made of a positive type photosensitive material in the diffraction grating. The horizontal axis is the exposure amount, the vertical axis is the residual film thickness ratio of the photosensitive layer after development, 51 is the intensity distribution of exposure interference fringes, 52 is the lattice cross-sectional shape after development,
53 is a sensitivity curve.
以上のように構成された回折格子についてその動作を説
明する。The operation of the diffraction grating configured as above will be explained.
コヒーレント光の三光束干渉によって基板４３上の感光
性樹脂層４２に露光される干渉縞のコントラストは基板
平面上で干渉縞の線方向と垂直な方向をＸとすると、各
々の参照先の平均強度を■、波長をλ、露光角をθとし
て、Ｘ方向のコントラストＣ（ｘ）は Ｃ（ｘ） −
１（１−ｃｏｓ （２πｘ／ｄ）） ＋δ となる。The contrast of the interference fringes exposed on the photosensitive resin layer 42 on the substrate 43 by three-beam interference of coherent light is the average intensity of each reference point, where X is the direction perpendicular to the line direction of the interference fringes on the substrate plane. Assuming that ■, the wavelength is λ, and the exposure angle is θ, the contrast in the X direction C(x) is C(x) −
1(1-cos(2πx/d))+δ.
但し、 ｄ＝λ／ ｓ ｉｎ（θ／２） であり、δ
はバイアス光強度である。従って、強度分布は５１は一
般に三角関数となる。感度曲線５３は右下がりの線形関
数となっているので、強度分布５１の干渉縞で露光する
と格子断面形状５２を有する回折格子となる。これは格
子溝間隔ｄで正弦波溝を有する回折格子であり、反射膜
４１を設けることにより反射型回折格子となる。However, d=λ/s in(θ/2), and δ
is the bias light intensity. Therefore, the intensity distribution 51 is generally a trigonometric function. Since the sensitivity curve 53 is a linear function that slopes downward to the right, exposure with interference fringes of the intensity distribution 51 results in a diffraction grating having a grating cross-sectional shape 52. This is a diffraction grating having sinusoidal grooves with a grating groove interval d, and by providing a reflective film 41, it becomes a reflection type diffraction grating.
第６図に第４図の正弦波溝形状を有する反射型回折格子
におけるリトロ−配置での回折効率をあられすグラフを
示す。但し、溝深さは格子溝間隔ｄに対して０．３５の
比率であり、格子表面の反射膜は完全導体としている。FIG. 6 shows a graph showing the diffraction efficiency in the Littrow arrangement of the reflection type diffraction grating having the sinusoidal groove shape shown in FIG. However, the groove depth has a ratio of 0.35 to the grating groove spacing d, and the reflective film on the grating surface is a perfect conductor.
横軸は格子溝間隔ｄと波長λの比率（以後、λ／４と称
する）である。６１は偏光方向が格子溝方向と平行な成
分（以後、Ｅ波成分と称する）の効率曲線、６２は偏光
方向が格子溝方向に対して垂直な成分（以後、Ｈ波成分
と称する）の効率曲線、６３は無偏光の場合の効率曲線
である。一つの回折格子を考える場合、ｄは一定である
ので横軸は波長と等価と考えてよい。The horizontal axis is the ratio of the grating groove spacing d to the wavelength λ (hereinafter referred to as λ/4). 61 is the efficiency curve of the component whose polarization direction is parallel to the grating groove direction (hereinafter referred to as the E-wave component), and 62 is the efficiency curve of the component whose polarization direction is perpendicular to the grating groove direction (hereinafter referred to as the H-wave component). Curve 63 is an efficiency curve for non-polarized light. When considering one diffraction grating, since d is constant, the horizontal axis can be considered to be equivalent to the wavelength.
発明が解決しようとする問題点
しかしながら上記のような構成では、第６図から無偏光
効率曲線６３で高い回折効率が得られる範囲はλ／４が
０，６５から０．８５であり、特にλ／４が０６６５付
近では回折効率が急激に減少している。さらにλ／４が
大きくなると、Ｈ波成分の効率はあまり変化しないのに
対して、Ｅ波成分の効率は減少し、結果的に無偏光の回
折効率が減少する。そしてλ／４が０．９以上の領域で
は各偏光成分による回折効率の差が大きくなって偏光依
存性が著しくなるという問題点を有していた。Problems to be Solved by the Invention However, in the above configuration, as shown in FIG. 6, the range in which high diffraction efficiency can be obtained in the non-polarized light efficiency curve 63 is λ/4 from 0.65 to 0.85, and especially when λ When /4 is around 0665, the diffraction efficiency decreases rapidly. When λ/4 further increases, the efficiency of the H-wave component does not change much, but the efficiency of the E-wave component decreases, resulting in a decrease in the diffraction efficiency of non-polarized light. In a region where λ/4 is 0.9 or more, there is a problem in that the difference in diffraction efficiency between each polarization component becomes large and polarization dependence becomes significant.
本発明は上記問題点を鑑み、無偏光での回折効率が高く
なる波長範囲を広げ、−偏光依存性を軽減する回折格子
を提供するものである。In view of the above-mentioned problems, the present invention provides a diffraction grating that widens the wavelength range in which the diffraction efficiency is high in non-polarized light and reduces polarization dependence.
問題点を解決するための手段
上記問題点を解決するために本発明の回折格子は基板と
、その上に設ける感光性材料よりなる感光層と、感光層
の上に設ける反射膜から成り、感光層が露光量と現像後
の感光層膜の残存膜厚率を表す曲線の２次微分が正の値
であるような感度特性をもつという構成をとるものであ
る。Means for Solving the Problems In order to solve the above problems, the diffraction grating of the present invention consists of a substrate, a photosensitive layer made of a photosensitive material provided on the substrate, and a reflective film provided on the photosensitive layer. The layer has a sensitivity characteristic such that the second derivative of the curve representing the exposure amount and the residual film thickness ratio of the photosensitive layer after development is a positive value.
作用
本発明は上記した構成によって、三角関数の露光干渉縞
のコントラストで露光すると、感光層の感度曲線の非線
形性のために、現像された後の回折格子の断面形状が広
いλ／４の範囲で高い無偏光での回折効率を有し、偏光
依存性を軽減できる回折格子の断面形状となる。Effects of the present invention With the above configuration, when exposed with the contrast of exposure interference fringes of trigonometric functions, the cross-sectional shape of the developed diffraction grating has a wide range of λ/4 due to the nonlinearity of the sensitivity curve of the photosensitive layer. This results in a cross-sectional shape of the diffraction grating that has high diffraction efficiency in unpolarized light and can reduce polarization dependence.
実施例
以下本発明の一実施例の回折格子について図面を参照し
ながら説明する。EXAMPLE A diffraction grating according to an example of the present invention will be described below with reference to the drawings.
第１図は本発明の一実施例における回折格子の断面形状
を示すものである。第゛１図において１）は反射膜、１
２は感光性材料よりなる感光層、１３は基板である。FIG. 1 shows the cross-sectional shape of a diffraction grating in one embodiment of the present invention. In Figure 1, 1) is a reflective film, 1
2 is a photosensitive layer made of a photosensitive material, and 13 is a substrate.
第２図は、第１図の回折格子のうちポジ型の感光性材料
よりなる感光層の感度曲線を表した図である。横軸は露
光量、縦軸は現像後の感光層膜厚の残存膜厚率、２１は
露光干渉縞の強度分布、２２は現像後の格子断面形状、
２３は感度曲線である。FIG. 2 is a diagram showing a sensitivity curve of a photosensitive layer made of a positive type photosensitive material in the diffraction grating of FIG. 1. FIG. The horizontal axis is the exposure amount, the vertical axis is the residual film thickness ratio of the photosensitive layer after development, 21 is the intensity distribution of exposure interference fringes, 22 is the lattice cross-sectional shape after development,
23 is a sensitivity curve.
第３図は、第１図の格子断面形状を有する反射型回折格
子におけるリトロ−配置での回折効率をあられすグラフ
を示す。但し、溝深さは格子溝間隔ｄに対して０．４３
５の比率であり、格子表面の反射膜は完全導体としてい
る。横軸は格子溝間隔ｄと波長λの比率（λ／４）であ
る。３１はＥ波成分の効率曲線、３２はＨ波成分の効率
曲線、３３は無偏光の場合の効率曲線である。一つの回
折格子を考える場合、ｄは一定であるので横軸は波長と
等価と考えてよい。FIG. 3 shows a graph showing the diffraction efficiency in a Littrow configuration for a reflection type diffraction grating having the grating cross-sectional shape of FIG. However, the groove depth is 0.43 for the lattice groove spacing d.
5, and the reflective film on the grating surface is a perfect conductor. The horizontal axis is the ratio (λ/4) of the grating groove spacing d to the wavelength λ. 31 is an efficiency curve of the E-wave component, 32 is an efficiency curve of the H-wave component, and 33 is an efficiency curve in the case of non-polarized light. When considering one diffraction grating, since d is constant, the horizontal axis can be considered to be equivalent to the wavelength.
以上のように構成された回折格子について、その動作を
説明する。The operation of the diffraction grating configured as described above will be explained.
コヒーレント光の三光束干渉□によって基板１３上の感
光層１２に露光される干渉縞のコントラストは強度分布
２１のように一般に三角関数となる。感度曲線２３は、
その曲線の２次微分が正値であるので露光量が大きくな
るにつれて、それに対する感光層の残存膜厚率の変化は
低くなる。従って、強度分布２１の干渉縞で露光すると
現像後の格子断面形状２２を有する回折格子となり、そ
の上に反射膜１）を設けることにより反射型回折格子と
なる。作成された格子形状は正弦波状の形状に比べ、格
子溝の山の部分が鋭＜、谷の部分が丸くなっている特−
殊な形状となワている。このような形状を有する回折格
子の回折効率は第３図でわかるように無偏光で、λ／４
が０．７から１．１の範囲で高く、偏光依存性もλ／４
が１．１まではあまり顕著に現れない。The contrast of the interference fringes exposed on the photosensitive layer 12 on the substrate 13 by the three-beam interference □ of coherent light generally becomes a trigonometric function like the intensity distribution 21. The sensitivity curve 23 is
Since the second derivative of the curve is a positive value, as the exposure amount increases, the change in the residual film thickness ratio of the photosensitive layer decreases. Therefore, when exposed to interference fringes having an intensity distribution 21, the diffraction grating becomes a diffraction grating having a grating cross-sectional shape 22 after development, and by providing the reflective film 1) thereon, it becomes a reflective diffraction grating. Compared to a sinusoidal shape, the created lattice shape has sharp peaks and rounded valleys.
It has a special shape. As can be seen in Figure 3, the diffraction efficiency of a diffraction grating with such a shape is λ/4 for non-polarized light.
is high in the range of 0.7 to 1.1, and the polarization dependence is also λ/4
does not appear very clearly until 1.1.
以上のように本実施例によれば、基板と感光層と反射膜
の構成をとり、感光層が露光量と現像後の感光層膜の残
存膜厚率を表す曲線の２次微分が正の値であるような感
度特性をもつことにより、無偏光の回折効率が高いλ／
４の範囲を、従来の線形な感度特性をもつ感光層で作製
した正弦波溝格子に比べ、約２倍で実現することができ
、偏光依存性が小さい領域もλ／４の大きい方ヘシフト
することができる。As described above, according to this embodiment, the structure of the substrate, the photosensitive layer, and the reflective film is adopted, and the photosensitive layer has a positive quadratic differential of the curve representing the exposure amount and the residual film thickness ratio of the photosensitive layer film after development. By having a sensitivity characteristic that is a value of λ/
4 can be achieved in approximately twice the range of conventional sinusoidal groove gratings made with photosensitive layers with linear sensitivity characteristics, and the region with small polarization dependence is also shifted to the larger λ/4. be able to.
尚、上記実施例では、第３図の感度曲線としてポジ型の
感光性材料について述べたが、ネガの感光性材料でも同
等の効果を得ることができる。Incidentally, in the above embodiment, a positive type photosensitive material was described as the sensitivity curve in FIG. 3, but the same effect can be obtained with a negative type photosensitive material.
発明の効果
以上のように本発明は、基板と、その上に設ける感光性
材料よりなる感光層と、感光層の上に設ける反射膜から
成り、感光層が露光量と現像後の感光層膜の残存膜厚率
を表す曲線の２次微分が正の値であるような感度特性を
もつ構成にすることにより、従来の線形な感度特性をも
つ感光層で作製した正弦波溝格子に比べ、無偏光で高い
回折効率を広い波長範囲で実現し、しかも各偏光による
回折効率の偏りを少なくさせることができる。Effects of the Invention As described above, the present invention consists of a substrate, a photosensitive layer made of a photosensitive material provided on the substrate, and a reflective film provided on the photosensitive layer, and the photosensitive layer has a function of adjusting the exposure amount and the photosensitive layer film after development. By creating a structure with sensitivity characteristics such that the second derivative of the curve representing the residual film thickness ratio is a positive value, compared to a sinusoidal groove grating made with a conventional photosensitive layer with linear sensitivity characteristics It is possible to achieve high diffraction efficiency over a wide wavelength range with non-polarized light, and to reduce the deviation in diffraction efficiency due to each polarization.
第１図は本発明の一実施例における回折格子の断面形状
を示す説明図、第２図は第１図のポジ型の感光性材料よ
りなる感光層の感度曲線を表した説明図、第３図は第１
図の格子断面形状を有する反射型回折格子におけるリト
ロ−配置での回折効率を表した説明図、第４図は従来の
回折格子の断面形状を示す説明図、第５図は第４図のポ
ジ型の感光性材料よりなる感光層の感度曲線を表した説
°明図、第６図は第４図の格子断面形状を有する反射型
回折格子におけるリトロ−配置での回折効率を表した説
明図である。
１）・・・・・・反射膜、１２・・・・・・感光層、１
３・・・・・・基板、２１・・・・・・露光干渉縞の強
度分布、２２・・・・・・現像後の格子断面形状、２３
・・・・・・感度曲線、３１・・・・・・Ｅ波成分の効
率曲線、３２・・・・・・Ｈ波成分の効率曲線、３３・
・・・・・無偏光の場合の効率曲線。
代理人の氏名 弁理士 中尾敏男 ばか１名纂 ３ＦＪ
Ｊ
ス／ｄ
憾 綜
蛮捗諮叫笹
第４図
−ぐ
箒５図
第６図
λ／ｄFIG. 1 is an explanatory diagram showing the cross-sectional shape of a diffraction grating in one embodiment of the present invention, FIG. 2 is an explanatory diagram showing the sensitivity curve of the photosensitive layer made of the positive type photosensitive material of FIG. The figure is the first
An explanatory diagram showing the diffraction efficiency in a Littrow arrangement in a reflection type diffraction grating having the grating cross-sectional shape shown in the figure, Figure 4 is an explanatory diagram showing the cross-sectional shape of a conventional diffraction grating, and Figure 5 shows the positive side of Figure 4. FIG. 6 is an explanatory diagram showing the sensitivity curve of a photosensitive layer made of a photosensitive material of the type shown in FIG. It is. 1)... Reflective film, 12... Photosensitive layer, 1
3... Substrate, 21... Intensity distribution of exposure interference fringes, 22... Grating cross-sectional shape after development, 23
......Sensitivity curve, 31...Efficiency curve of E wave component, 32...Efficiency curve of H wave component, 33.
...Efficiency curve for non-polarized light. Name of agent: Patent attorney Toshio Nakao Compiled by one idiot 3FJ
J Su / d Sorry Soban Progress Consultation Sasa Figure 4 - Gu Houki Figure 5 Figure 6 λ / d
Claims (3)
層の上に設ける反射膜とを具備し、前記感光層が露光量
と現像後の前記感光層膜の残存膜厚率を表す曲線の２次
微分が正の値であるような感度特性をもつことを特徴と
する回折格子。(1) A substrate, a photosensitive layer provided on the substrate, and a reflective film provided on the photosensitive layer, wherein the photosensitive layer represents the amount of exposure and the residual film thickness percentage of the photosensitive layer after development. A diffraction grating characterized by having sensitivity characteristics such that the second derivative of the curve is a positive value.
特徴とする特許請求の範囲第（１）項記載の回折格子。(2) The diffraction grating according to claim (1), characterized in that a positive photosensitive material is used as a material for the photosensitive layer.
特徴とする特許請求の範囲第（１）項記載の回折格子。(3) The diffraction grating according to claim (1), characterized in that a negative photosensitive material is used as a material for the photosensitive layer.
Priority Applications (7)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62331978A JPH01172902A (en) | 1987-12-28 | 1987-12-28 | Diffraction grating |
| US07/290,196 US5007709A (en) | 1987-12-28 | 1988-12-17 | Diffraction grating and manufacturing method thereof |
| EP88312373A EP0323238B1 (en) | 1987-12-28 | 1988-12-28 | Diffraction grating and manufacturing method thereof |
| KR1019880017677A KR920001246B1 (en) | 1987-12-28 | 1988-12-28 | Diffraction gratings, manufacturing method thereof and manufacturing system thereof |
| EP95202075A EP0682272A2 (en) | 1987-12-28 | 1988-12-28 | Diffraction grating manufacturing method and apparatus |
| DE3855042T DE3855042T2 (en) | 1987-12-28 | 1988-12-28 | Diffraction grating and method for its production |
| CA000587161A CA1321495C (en) | 1987-12-28 | 1988-12-28 | Diffraction grating and manufacturing method thereof |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP62331978A JPH01172902A (en) | 1987-12-28 | 1987-12-28 | Diffraction grating |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| JPH01172902A true JPH01172902A (en) | 1989-07-07 |
Family
ID=18249775
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP62331978A Pending JPH01172902A (en) | 1987-12-28 | 1987-12-28 | Diffraction grating |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JPH01172902A (en) |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS50114245A (en) * | 1973-11-13 | 1975-09-08 |
-
1987
- 1987-12-28 JP JP62331978A patent/JPH01172902A/en active Pending
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS50114245A (en) * | 1973-11-13 | 1975-09-08 |
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