JPH059028B2 - - Google Patents

Info

Publication number
JPH059028B2
JPH059028B2 JP4962186A JP4962186A JPH059028B2 JP H059028 B2 JPH059028 B2 JP H059028B2 JP 4962186 A JP4962186 A JP 4962186A JP 4962186 A JP4962186 A JP 4962186A JP H059028 B2 JPH059028 B2 JP H059028B2
Authority
JP
Japan
Prior art keywords
phase shift
hologram
phase
wavefront
diffraction grating
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 - Lifetime
Application number
JP4962186A
Other languages
Japanese (ja)
Other versions
JPS62206583A (en
Inventor
Juzo Ono
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
NEC Corp
Original Assignee
Nippon Electric Co Ltd
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by Nippon Electric Co Ltd filed Critical Nippon Electric Co Ltd
Priority to JP4962186A priority Critical patent/JPS62206583A/en
Publication of JPS62206583A publication Critical patent/JPS62206583A/en
Publication of JPH059028B2 publication Critical patent/JPH059028B2/ja
Granted legal-status Critical Current

Links

Description

【発明の詳細な説明】 [産業上の利用分野] この発明はホログラムおよび位相シフト回折格
子の製造方法に関し、特にDFB(デイストリビユ
ーテツト・フイード・バツク、分布帰還)型半導
体レーザの単一軸モード化に用いられる位相シフ
ト回折格子の製造方法に関するものである。
[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a method for manufacturing a hologram and a phase-shifted diffraction grating, and in particular to a method for manufacturing a hologram and a phase-shifted diffraction grating, and particularly to a method for manufacturing a hologram and a phase-shifted diffraction grating, and in particular, a method for manufacturing a hologram and a phase-shifted diffraction grating. The present invention relates to a method for manufacturing a phase shift diffraction grating used in

[従来技術] 半導体レーザの縦モードを単一化することは、
光フアイバ通信における波長分散による波形歪の
防止、安定な高速変調による超高速伝送、雑音の
低減や光応用計測等において極めて重要な課題で
ある。しかし、フアブリペロ型共振器を有する半
導体レーザでは、縦モード選択性が十分ではない
ので共振器に回折格子を内蔵したDFBレーザが
開発された。全体に一様な構造のDFBレーザで
は2つの縦モードが発振するため、回折格子の中
央付近に1/4波長相当の位相シフトを付加した回
折格子を用いる方法が採られている。
[Prior art] Unifying the longitudinal mode of a semiconductor laser is
This is an extremely important issue in optical fiber communications, such as preventing waveform distortion due to wavelength dispersion, ultra-high-speed transmission through stable high-speed modulation, noise reduction, and optical application measurement. However, semiconductor lasers with Fabry-Perot resonators do not have sufficient longitudinal mode selectivity, so a DFB laser with a built-in diffraction grating in the resonator was developed. Since a DFB laser with an overall uniform structure oscillates in two longitudinal modes, a method is used that uses a diffraction grating with a phase shift equivalent to 1/4 wavelength added near the center of the diffraction grating.

このような位相シフト回折格子の製造方法とし
ては、ポジ、ネガ2種類のレジストを使い分け
て、これらの各領域の位相を反転させることによ
り、1/4波長相当分の位相シフトを生じさせる方
法がある。
One way to manufacture such a phase-shift diffraction grating is to use two types of resist, positive and negative, and invert the phase of each of these regions to create a phase shift equivalent to 1/4 wavelength. be.

また、他の方法として、位相シフトに相当する
段差を有する石英のコンタクトマスクを用いる方
法である。前者についての文献としては、宇高勝
之他著の「電子通信学会技術報告」、OQE85−11
巻、第69〜第76頁に記載の論文「λ/4シフト
InGaAsP/InP DFBレーザ」があり、また後者
についての文献としては、白崎正孝他著の「電子
通信学会技術報告」、OQE85−60巻、第57〜第64
頁に記載の論文「DFBレーザ用1/4波長シフト回
折格子の形成方法の提案−位相マスクの考案とそ
の効果−」がある。
Another method is to use a quartz contact mask having a step corresponding to a phase shift. Literature regarding the former includes ``Technical Report of the Institute of Electronics and Communication Engineers'' by Katsuyuki Udaka et al., OQE85-11.
vol., pp. 69-76, the paper “λ/4 Shift
``InGaAsP/InP DFB laser'', and the literature on the latter includes ``Technical Report of the Institute of Electronics and Communication Engineers'' by Masataka Shirasaki et al., OQE85-60, Volumes 57 to 64.
There is a paper titled ``Proposal of a method for forming a 1/4 wavelength shift diffraction grating for DFB lasers - Invention of a phase mask and its effects'' on page 1.

[発明が解決しようとする問題点] 上述の従来技術には、次のような問題点があ
る。第1のポジ、ネガ2種類のレジストを使いわ
ける方法には、レジスト塗布、現像、エツチング
ともに各3回という非常に多数のプロセス工程を
必要とし、その結果歩留りが低いという問題点が
あつた。又、第2のコンタクトマスクを用いる方
法には、コンタクトマスクでの光の回折のために
光の位相が変化し、位相シフト部分に所望の格子
が形成されず、いわゆる遷移領域ができてしまう
という問題点があり、また回折格子の周期毎に異
なるコンタクトマスクを用意しなければならない
という問題点もあつた。
[Problems to be Solved by the Invention] The above-mentioned conventional technology has the following problems. The first method of selectively using two types of resist, positive and negative, required a very large number of process steps of resist coating, development, and etching three times each, resulting in a problem of low yield. Furthermore, in the method using the second contact mask, the phase of the light changes due to the diffraction of the light in the contact mask, and the desired grating is not formed in the phase shift portion, resulting in the formation of a so-called transition region. There were also problems in that a different contact mask had to be prepared for each period of the diffraction grating.

本発明の目的は、このような従来技術の問題点
を解決し、簡便なプロセス工程で、しかも位相シ
フト部の遷移領域が小さくでき、また回折格子の
周期によらず適用できるホログラムおよび位相シ
フト回折格子の製造方法を提供することにある。
It is an object of the present invention to solve the problems of the prior art, to provide a hologram and phase shift diffraction system that can be used in simple process steps, in which the transition region of the phase shift section can be made small, and that can be applied regardless of the period of the diffraction grating. An object of the present invention is to provide a method for manufacturing a lattice.

[問題点を解決するための手段] 第1の発明のホログラムの製造方法の構成は、
所望の位相シフトを生じさせる位相板を斜入射の
平行光で照射して得られる回折波面と参照光束と
の干渉光を感光体層に照射し、この感光体層上に
前記干渉光による凹凸を形成したことを特徴とす
る。
[Means for solving the problem] The configuration of the hologram manufacturing method of the first invention is as follows:
A photoreceptor layer is irradiated with interference light between a diffraction wavefront obtained by irradiating obliquely incident parallel light onto a phase plate that produces a desired phase shift and a reference light beam, and unevenness is created on the photoreceptor layer by the interference light. It is characterized by the fact that it has been formed.

第2の発明の位相シフト回折格子の製造方法の
構成は、所望の位相シフトを生じさせる位相板を
斜入射の平行光で照射して得られる回折波面を、
参照光束と干渉させてホログラムを製造する第1
の工程と、前記ホログラムを前記参照光と共役な
波面で照射して得られる波面を、前記位相板の配
置されていた面で平行光束と干渉させてウエハー
上に設けた感光体に照射し、この感光体上に位相
シフト回折格子を形成する第2の工程とを含むこ
とを特徴とする。
The configuration of the method for manufacturing a phase shift diffraction grating according to the second invention is such that a diffraction wavefront obtained by irradiating a phase plate that causes a desired phase shift with obliquely incident parallel light,
The first step is to produce a hologram by interfering with the reference beam.
and a wavefront obtained by irradiating the hologram with a wavefront conjugate with the reference light, which is caused to interfere with a parallel beam of light on the surface where the phase plate was arranged, and irradiates a photoreceptor provided on a wafer; The method is characterized in that it includes a second step of forming a phase shift diffraction grating on the photoreceptor.

[作用] 本発明の作用・原理は次の通りである。[Effect] The operation and principle of the present invention are as follows.

本発明では、回折格子を製作するために2光束
干渉露光法を用い、この2光束のうちの一方の光
束が干渉面で位相シフトした波面になるようなホ
ログラフイの原理を用いて、このような波面を発
生させることを基本原理としている。ホログラム
には波面を凍結し、再生できる特徴がある。
In the present invention, a two-beam interference exposure method is used to manufacture the diffraction grating, and the principle of holography is used in which one of the two beams becomes a wavefront whose phase is shifted at the interference surface. The basic principle is to generate a wave front. Holograms have the ability to freeze wavefronts and reproduce them.

本発明では、まず所望の位相シフトを生じさせ
る位相板を平行光で照射して得られる波面を参照
波面と干渉させてホログラムを形成する。このホ
ログラムは、位相板での回折波面を記録している
ので、ホログラムを製作した時の参照波面と共役
な照明光でホログラムを裏面から照射すると、位
相板からの波面の逆進波面が再生されるので、ホ
ログラム製作時に位相板が置かれていた面上では
位相板透過直後の、すなわち所望の位相シフトし
た波面の逆進波面が得られることになる。そこで
この波面と平行光束とを適当な角度で干渉させれ
ば、位相シフト干渉縞が得られ、この干渉縞を感
光体に記録することにより、位相シフト回折格子
を形成できる。
In the present invention, a hologram is first formed by irradiating a phase plate that produces a desired phase shift with parallel light and causing the obtained wavefront to interfere with a reference wavefront. This hologram records the diffracted wavefront from the phase plate, so when the hologram is illuminated from the back with illumination light that is conjugate to the reference wavefront when the hologram was manufactured, the backward wavefront of the wavefront from the phase plate is reproduced. Therefore, on the surface where the phase plate was placed during the hologram production, a reversed wavefront of a wavefront immediately after passing through the phase plate, that is, a wavefront with a desired phase shift, is obtained. Therefore, by interfering this wavefront with a parallel light beam at an appropriate angle, phase shift interference fringes can be obtained, and by recording these interference fringes on a photoreceptor, a phase shift diffraction grating can be formed.

[実施例] 以下本発明の実施例について図面を参照して説
明する。なお以下の説明では説明を容易にするた
めに、位相板の段差や回折格子の溝を実際よりも
拡大して模式的に示している。
[Examples] Examples of the present invention will be described below with reference to the drawings. Note that in the following description, in order to facilitate the explanation, the steps of the phase plate and the grooves of the diffraction grating are schematically illustrated in a larger scale than in reality.

第1図は、本願の第1の発明のホログラムの製
作光学系の一例を示す断面図である。所望の位相
シフトを与える位相板1を斜入射の平行光2で照
射し、透過波3を可干渉な平行参照光4と干渉さ
せて、基板6上の感光体層5に記録する。
FIG. 1 is a sectional view showing an example of a hologram manufacturing optical system according to the first invention of the present application. A phase plate 1 giving a desired phase shift is irradiated with obliquely incident parallel light 2, and a transmitted wave 3 is caused to interfere with a coherent parallel reference light 4 and recorded on a photoreceptor layer 5 on a substrate 6.

本実施例では、光源として波長325mmのHe−
Cdレーザを用いたため、位相板1は325mmの光を
透過する石英にエツチングにより、形成され、1/
4波長の位相シフト格子を複数同一ウエハー上に
形成するため、位相板1には複数の位相シフト部
を設けている。また、感光体層5には、フオトレ
ジストAZ−1350を用いて、この感光体層5を現
象後そのままホログラムとして用いることもでき
るが、長期にわたつて使用するためには、記録さ
れたフオトレジストパターンをマスクとして、石
英基板6にエツチングで転写しておくことが好ま
しい。フオトレジストのままで用いる場合のフオ
トレジストの溝深さ、及び石英基板6に転写して
用いる場合の溝深さは、両者ともに約0.5μm程度
で、約30%の回折効率が得られた。
In this example, the light source is He-2 with a wavelength of 325 mm.
Since a Cd laser was used, the phase plate 1 was formed by etching quartz that transmits 325 mm of light.
In order to form a plurality of four-wavelength phase shift gratings on the same wafer, the phase plate 1 is provided with a plurality of phase shift parts. In addition, photoresist AZ-1350 can be used for the photoresist layer 5, and this photoresist layer 5 can be used as a hologram as it is after the phenomenon, but in order to use it for a long time, it is necessary to It is preferable to transfer the pattern onto the quartz substrate 6 by etching using the pattern as a mask. The groove depth of the photoresist when used as is and the groove depth when transferred to the quartz substrate 6 were both about 0.5 μm, and a diffraction efficiency of about 30% was obtained.

第2図は本願の第2の発明のホログラムを用い
た位相シフト回折格子の製作光学系の一例を示す
断面図である。この図で石英基板6上にホログラ
ム7が形成されている。このホログラム7を製作
時の波面(第2図の平行光4)と共役な波面8
を、このホログラム7の裏面から照射すると、回
折波9を生じる。この回折波9はホログラム製作
時の位相板透過波面(第2図の波面3)の逆進波
面である。そこでホログラム製作時に位相板1の
あつた位置には、位相板透過直後の、すなわち位
相シフトした波面が出来ている。この位置に感光
体であるフオトレジスト11を塗布したウエハー
10を置いて、もう一方の干渉光束12と干渉さ
せることにより、位相シフト格子を形成できる。
FIG. 2 is a sectional view showing an example of an optical system for manufacturing a phase shift diffraction grating using a hologram according to the second invention of the present application. In this figure, a hologram 7 is formed on a quartz substrate 6. This hologram 7 is a wavefront 8 that is conjugate to the wavefront at the time of production (parallel light 4 in Figure 2).
When irradiated from the back side of this hologram 7, a diffracted wave 9 is generated. This diffracted wave 9 is a reverse wavefront of the wavefront transmitted through the phase plate (wavefront 3 in FIG. 2) during hologram fabrication. Therefore, at the position where the phase plate 1 was placed during the production of the hologram, a wavefront immediately after passing through the phase plate, that is, a phase-shifted wavefront is created. A phase shift grating can be formed by placing a wafer 10 coated with a photoresist 11, which is a photoreceptor, at this position and causing it to interfere with the other interference light beam 12.

なお、本実施例では、波長1.5μmの半導体レー
ザ用に0.2μm周期の回折格子を形成するために、
ウエハー10に対する2光束9,12の入射角は
各々50.7゜とした。また、光束9の入射角は固定
で、光束12の入射角を変えることで格子周期を
変えることができる。また、本実施例において、
第1図に示したように表面に対して垂直に溝が形
成された位相板1を用いると、段差部分での透過
光の位相シフトが急峻でなくなり、結果的に遷移
領域が拡大してしまう。
In this example, in order to form a diffraction grating with a period of 0.2 μm for a semiconductor laser with a wavelength of 1.5 μm,
The angles of incidence of the two light beams 9 and 12 on the wafer 10 were each 50.7°. Further, the incident angle of the light beam 9 is fixed, and the grating period can be changed by changing the incident angle of the light beam 12. Furthermore, in this example,
If a phase plate 1 with grooves formed perpendicular to the surface is used as shown in Fig. 1, the phase shift of the transmitted light at the stepped portion will not be as steep, resulting in an enlarged transition region. .

第3図は第1の本発明の他の実施例の好ましい
位相板13を示した側面図である。本実施例は、
図に示すように斜入射の平行光束2に平行な溝の
側面を持つ位相板13を用いることで遷移領域の
小さい位相シフト格子を形成できる。
FIG. 3 is a side view showing a preferred phase plate 13 according to another embodiment of the first invention. In this example,
As shown in the figure, a phase shift grating with a small transition region can be formed by using a phase plate 13 having grooved side surfaces parallel to the obliquely incident parallel light beam 2.

[発明の効果] 以上に説明したように、本発明によれば、通常
の干渉露光法と同じように簡便な工程で、位相シ
フト部の遷移領域の小さい、任意の周期を有する
位相シフト回折格子が製造できる。
[Effects of the Invention] As explained above, according to the present invention, a phase shift diffraction grating having a small transition region of a phase shift portion and having an arbitrary period can be produced using a simple process similar to a normal interference exposure method. can be manufactured.

【図面の簡単な説明】[Brief explanation of the drawing]

第1図は第1の発明の一実施例を説明する光学
系の断面図、第2図は第2の発明の位相シフト回
折格子の製作時の光学系を示す断面図、第3図は
第1の発明に用いる好ましい位相板を説明するた
めのホログラムの製作光学系の断面図である。 1,13……位相板、2,4,8,12……平
行光束、3,9……回折波面、5,11……感光
体層、6……石英基板、7……ホログラム、10
……ウエハー。
FIG. 1 is a cross-sectional view of an optical system for explaining an embodiment of the first invention, FIG. 2 is a cross-sectional view of the optical system when manufacturing a phase shift grating of the second invention, and FIG. FIG. 1 is a cross-sectional view of a hologram production optical system for explaining a preferable phase plate used in the first invention. 1, 13... Phase plate, 2, 4, 8, 12... Parallel light beam, 3, 9... Diffraction wave front, 5, 11... Photoreceptor layer, 6... Quartz substrate, 7... Hologram, 10
...Wafer.

Claims (1)

【特許請求の範囲】 1 所望の位相シフトを生じさせる位相板を斜入
射の平行光で照射して得られる回折波面と参照光
束との干渉光を感光体層に照射し、この感光体層
上に前記干渉光による凹凸を形成することを特徴
とするホログラムの製造方法。 2 所望の位相シフトを生じさせる位相板を斜入
射の平行光で照射して得られる回折波面を、参照
光束と干渉させてホログラムを製作する第1の工
程と、前記ホログラムを前記参照光と共役な波面
で照射して得られる波面を、前記位相板の配置さ
れていた面で平行光束と干渉させてウエハー上に
設けた感光体に照射し、この感光体に位相シフト
回折格子を形成する第2の工程とを含むことを特
徴とする位相シフト回折格子の製造方法。 (3) 位相板が溝の有無によつて位相シフトを生じ
る位相板からなり、かつ前記溝の側面が斜入射平
行光の光束とほぼ平行になつていることを特徴と
する特許請求の範囲第2項記載の位相シフト回折
格子の製造方法。
[Scope of Claims] 1. A photoreceptor layer is irradiated with interference light between a diffraction wavefront obtained by irradiating a phase plate that produces a desired phase shift with obliquely incident parallel light and a reference light beam, and the photoreceptor layer is A method for manufacturing a hologram, characterized in that unevenness is formed by the interference light. 2. A first step of manufacturing a hologram by interfering with a reference beam a diffraction wavefront obtained by irradiating a phase plate that produces a desired phase shift with obliquely incident parallel light, and conjugating the hologram with the reference beam. The wavefront obtained by irradiation with a wavefront is caused to interfere with a parallel beam on the surface where the phase plate was arranged, and is irradiated onto a photoreceptor provided on a wafer, forming a phase shift diffraction grating on this photoreceptor. 2. A method for manufacturing a phase shift diffraction grating, comprising the steps of 2. (3) The phase plate is comprised of a phase plate that generates a phase shift depending on the presence or absence of grooves, and the side surfaces of the grooves are substantially parallel to the beam of obliquely incident parallel light. 2. A method for manufacturing a phase shift diffraction grating according to item 2.
JP4962186A 1986-03-07 1986-03-07 Production of hologram and phase shift diffraction grating Granted JPS62206583A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
JP4962186A JPS62206583A (en) 1986-03-07 1986-03-07 Production of hologram and phase shift diffraction grating

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
JP4962186A JPS62206583A (en) 1986-03-07 1986-03-07 Production of hologram and phase shift diffraction grating

Publications (2)

Publication Number Publication Date
JPS62206583A JPS62206583A (en) 1987-09-11
JPH059028B2 true JPH059028B2 (en) 1993-02-03

Family

ID=12836301

Family Applications (1)

Application Number Title Priority Date Filing Date
JP4962186A Granted JPS62206583A (en) 1986-03-07 1986-03-07 Production of hologram and phase shift diffraction grating

Country Status (1)

Country Link
JP (1) JPS62206583A (en)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH01144832U (en) * 1988-03-29 1989-10-04
KR101953318B1 (en) * 2012-03-20 2019-02-28 엘지디스플레이 주식회사 Manufacturing equipment of light path conversion film

Also Published As

Publication number Publication date
JPS62206583A (en) 1987-09-11

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