JP4247404B2 - Photonic crystal and manufacturing method thereof - Google Patents

Description

【００１１】
ここで、表1において、膜厚はコーティング膜の厚さであり同時にピラー型構造体の高さに相当する。また、ピラー直径はピラー型構造体の直径の平均値であり、*に限ってはピラー型構造体が楕円柱であるため、楕円の短径と長径を示した。
面積比はピラー型構造体底面の単位格子あたり占有面積比を次のように算出したものである：すなわち、電子顕微鏡により観察される図２の（ａ）に示されるような上方からの配列形状（後述の図１０参照）から単位格子の長さ（図２の（ａ）のハッチング部分は単位格子４つ分を示す）とピラー直径を知ることができるので、これを用い、図２の（ｂ）に示されるように底面においてピラー構造体の断面が占める単位格子当たり（図２の（ｂ）のハッチング部分は単位格子１つ分を示す）の面積比を算出した。
【００１２】
構造体の種類には、図1、図2、および図3に示す錐型、図5に示すようにピラー型構造体3が不規則な本数でかつ頂部3Pがずれて錐型に集まって構成される変形錐型、図6に示されるように隣接するピラー型構造体が密着し塊団子状となった構造体、図7、図8に示す従来並列型がある。これらの構造は電子顕微鏡による観察によっても確認することができる。図１０および図１１には、本発明に従う錐型複合構造体の走査型電子顕微鏡（ＳＥＭ）写真を示している。
【００１３】
表１に示す評価においては、図1、図2、および図3に示される錐型複合構造体となるものが図4に示すように（後述する）光挿入箇所をz方向によってL1,L2と変えることで、フォトニックバンドギャップを示す波長域が連続的に変化することから◎、変形錐型は条件を少し改善することによって錐型複合構造体となることが期待できることから○、従来並列型については通常の二次元フォトニック結晶としてフォトニックバンドギャップを示すことからから△、塊団子状においてはフォトニック結晶としての効果が期待できないことから×と判断した。
【００１４】
表１に示す例においては、フォトミック結晶作製における光ビーム照射の条件として、膜厚1〜30μｍ、レーザー強度4〜25μＪ、照射時間1〜15min、ピラー直径0.5〜20μｍの範囲で変化させているが、驚くべきことに、いずれの場合においても、面積比（光透過性基板上におけるピラー型構造体底面の単位格子当たり占有面積比）を30〜45％にすることによって、錐型構造体が確実に形成される。これに対して、該占有面積比を30%未満にすると、錐型複合構造体を形成する各ピラーが細く、変形錐型あるいは並列従来型となってしまう等の問題があり好ましくない。
また、該面積比が45％を越えると並列従来型の二次元フォトニック結晶構造となるか、あるいは塊団子状となってしまう等の問題があり好ましくない。
【００１５】
かくして、本発明においては、コーティング膜への光ビーム照射の条件を適宜調整して、該占有面積比が30〜45％になるように光ビーム照射を行なった後、化学エッチングにより非照射部を取り除く。ここで、本発明における光ビーム照射には、レーザー干渉法を用いることが好ましく、図1に示すxy平面に対して図9のような周期的な光学強度分布を有するレーザー光をコーティング膜に照射する。
【００１６】
なお、このレーザー干渉法において、コーティング膜内に、あらかじめ光増感剤を入れておく場合は、光増感剤の吸収波長域に対応するレーザー光を用いることが必要である。特に空間コヒーレンスの優れたレーザーを用いることが図9に示す照射域と非照射域との境界が明確である光学強度分布を持つ光を照射するために重要である。
【００１７】
これによりピラー型構造体底面の単位格子あたり占有面積比を30〜45%の範囲に調整することを容易にして、この結果ピラー型構造体の自己組織化を起こさせ、図１および図3に示すように複数本のピラー構造体3がビーム照射側で倒れ寄り集まったように接合した錐型複合構造体3Gが形成される。なお、図３には４本単位の錐型複合構造体が図示されているが、本発明によって得られる錐型複合構造体はこれに限られず、2〜10数本単位、特にｎ²（ｎは２，３または４）本単位で寄り集まった錐型構造体を得ることができる。
【００１８】
本発明において、フォトニック結晶用の光感応性官能基を有する原料としては、例えばC=C二重結合部などのように光により耐薬品性の高い結合形態に変化する所謂光感応性有機物と高屈折率の無機物としてチタニアのような原料となる金属アルコキシドとの複合材料が好適である。また、このような有機−無機複合材料に限定されず、その他、有機材料や有機高分子などでも製造することが可能である。有機−無機複合材料を用いる場合には、熱処理条件によっては、有機成分を燃焼し、無機成分のみを残して作製することも可能である。
【００１９】
更に本発明において、光透過性板上へのコーティング膜を形成する方法としては、ディップコーティング、スピンコーティング、ロールコーティング、キャスト法などで行うことが可能である。
また化学エッチング剤としては、特別限定するものでなくプロパノールやエトキシエタノールなどのアルコール、酸、アルカリ等材料の種類に応じた一般公知の化学エッチング剤で良い。
【００２０】
【実施例】
本発明の実施例を図1〜図4に基づいて説明する。
＜実施例１＞
この実施例1は、表1のNo.16に記載したもので、レーザー干渉法により有機−無機複合材料から錐型複合構造体を製造するものであり、以下にそのステップ毎に説明する。
第1ステップ：
メタクリルオキシプロピルトリメトキシシランとフェニルトリメトキシシランの混合溶液に0.75等量の希薄酸性水溶液を加え、攪拌する（溶液Ａ）。別の容器に、チタニウムブトキサイドと1/4等量のメタクリル酸、同体積のプロパノールを加え攪拌する（溶液Ｂ）。このＢ溶液をＡ溶液に加え、混合した後、水と光重合開始剤を加え、さらに24時間攪拌しゾル溶液を調製した。ゾル溶液をガラス基板上にスピンコーティングし膜を作製した。
第2ステップ：
膜中の有機溶媒が揮発する100℃で30分間乾燥行って光感応性有機−無機複合膜を固化させた後、再度コーティングを行った。このように3回コーティングを繰り返してゲル膜を作製した。
第3ステップ：
このようにして得られた上記光感応性有機−無機複合膜に対して、波長800nmで1ビームあたり照射強度10μJのフェムト秒レーザー光を4本干渉させ、約3μｍの周期となる光を2分間照射する。
第4ステップ：
レーザー光を照射した後の膜をプロパノールで5分間化学エッチングし、その後、乾燥窒素を吹き付けて乾かした。
この結果、光透過性基板1上において4本のピラー型構造体3底面4の単位格子2あたり占有面積比が35%の錐型複合構造体3Gとなって、図3に示すようなガラス基板上に規則的に周期配列した周期構造体30が得られた。
三次元的な錐型複合構造体3Gが二次元周期で配列した周期構造体30は、後述のようにフォトニックバンドギャップを示す波長域が連続的に変化する。
第5ステップ：
エッチング後残った膜つまり周期構造体30を熱処理する。このときの温度は構造体中の有機物が残存する温度、例えば150℃で行った。
【００２１】
＜比較例＞
表1のNo.21を比較例として示す。実施例１の第1ステップと第2ステップを経て作製したコーティング膜（厚さ10μｍ）に対して、第3ステップと同様のレーザーを10μJで10分間照射した後。同様に第4ステップ及び第5ステップを行った。この結果、錐型複合構造体を作製することはできず、図7にしめすような塊団子状の構造体となった。このとき、光透過性基板1上におけるピラー型構造体3底面4の単位格子あたりの占有面積比を求めたところ、70%であった。
【００２２】
＜実施例２＞
次に表1のNo.6を本発明に従う第２の実施例として示す。
原材料となるアルコキシドとして溶液Aにはメタクリルオキシプロピルトリメトキシシランを、溶液Bにはジルコニウムプロポキシドを用いた場合には25μJのビームを1分間露光することで、光透過性基板1上において4本のピラー型構造体3底面4の単位格子2あたり占有面積比を35%にした錐型複合構造体3Gで構成した図3に示す周期構造体30が作製できた。
上記の実施例1及び2で作製した周期構造体30は、例えば異なる波長域にフォトニックバンドギャップを示すフォトニック結晶として用いることができる。
図４には上記の周期構造体30の横断面的説明図を示す。光が周期構造体30の側面から表面に対して平行に表面側L2を通る場合、この光通過ラインL2に掛かる錐型複合構造体3G部分は、周期Ｔ2で配列しているのに対し、光が周期構造体30の側面から基板側L1を平行に通る場合にはこの光通過ラインL1に掛かる錐型複合構造体3G部分は、周期Ｔ1となっている。この周期の違いによって、フォトニックバンドギャップが形成される波長域はL1を通る光とL2を通る光で大きく異なる。
実施例1及び2で得られた4本のピラー型構造体が寄り集まって作られた錐型複合構造体からなる周期構造体に関してはT1/T2=2となり、L1を通る光に対して現れるバンドギャップの約2倍の波長域にL2を通る場合のバンドギャップが現れた。
【００２３】
本発明に従えば、光透過性基板上においてピラー構造体の底面の単位格子あたり占有面積比を30〜45%にすることにより、複数本のピラー型構造体の頂部が集束した三次元的な錐型複合構造体が形成され、これが光透過性基板上に二次元周期で配列した周期構造体が確実に得られる。
この周期構造体は、その側面からの光挿入箇所を厚み方向に任意に変えることによってフォトニックバンドギャップを示す波長域が連続的に変化する。例えば、4本のピラー型構造体からなる場合は実施例1及び2で述べたが、9本のピラー型構造体が集まった場合には3倍、16本の場合には4倍の波長域においてバンドギャップが現れる。
このような特定の周期構造体から成る本発明のフォトニック結晶は、平面光回路に幅広く応用することができる。
【図面の簡単な説明】
【図1】 本発明のフォトニック結晶の1実施例を示す基板上の周期構造体の横断面的説明図である。
【図2】 本発明のフォトニック結晶の平面図である。(a)は上面からのものであり、(b)は基板側（底面）から見た場合を示す。
【図3】 本発明のフォトニック結晶の立体図である。
【図4】 本発明のフォトニック結晶の横断面図と光通過ラインの説明図である。
【図5】 ピラー型構造体が不規則な本数で錐型に集まって構成された変形錐型構造体の立体図である。
【図6】 隣接するピラー型構造体が密着して作られる塊団子状構造体の平面図である。
【図7】 従来方法により作製される並列従来型二次元フォトニック結晶の断面図である。
【図8】 従来方法により作製される並列従来型二次元フォトニック結晶の立体図である。
【図9】 本発明で用いたレーザー光の図1及び図3におけるxy平面での光強度分布を表す図である。
【図１０】 本発明のフォトニック結晶のSEM写真であり、上面からの状態が明示されている。
【図１１】 本発明のフォトニック結晶のSEM写真であり、錐型構造体が形成されていることが示されている。
【符号の説明】
１ 基板
２ 単位格子
２（４） 単位格子4つ分
２（１） 単位格子1つ分
３ ピラー型構造体
３Ｐ ピラー型構造体の頂部
３Ｂ ピラー型構造体の底部
３Ｇ 錐型複合構造体
３０ 周期構造体
Ｔ，ｔ 構造体の周期
Ｌ 光通過ライン
Ｉ 光の強度[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a photonic crystal and a manufacturing method thereof.
[0002]
[Prior art]
In the field of optoelectronics, photonic crystals have been developed for miniaturization and integration of optical elements.
A photonic crystal generally known from the past is a two-dimensional photonic crystal, and is a periodic structure in which pillar (cylindrical) type structures are extended in parallel in the thickness direction and arranged in a plane at a predetermined period. It has become. Since the refractive index periodically changes with respect to the incident wave from the side surface of the periodic structure, it exhibits an interference action with respect to the electromagnetic wave and prohibits the passage of the electromagnetic wave in a specific frequency region. This also means that light of a specific wavelength can be blocked. The forbidden band (screening band) in this case is called a photonic band gap. The effect of shielding electromagnetic waves and light having a specific wavelength is called a photonic band gap effect.
This two-dimensional photonic crystal is expected to be applied to a planar optical circuit as a high-efficiency semiconductor laser element, an optical waveguide, or the like.
[0003]
Such a two-dimensional photonic crystal is generally manufactured as follows.
A raw material containing a photosensitive functional group is coated on a substrate such as silicon to a predetermined thickness and dried, and then the surface of the coating film is irradiated with a light beam such as laser light. After irradiation, the non-irradiated portion of the coating film other than the light beam irradiated portion (etching resistant portion) is etched. As a result, as shown in FIGS. 7 and 8, a periodic structure 030 in which pillar-type structures 03 standing on the substrate 01 are periodically arranged in parallel is obtained. This periodic structure is used as a two-dimensional photonic crystal. If necessary, a two-dimensional photonic crystal in which the substrate 01 is further etched to form pillars on the extension of the pillar structure 03 is also manufactured.
[0004]
As another two-dimensional photonic crystal, for example, in Japanese Patent Application Laid-Open No. 2002-277659, a portion irradiated with a light beam is etched to form pores, and a filling material is selectively introduced into the pores to change the refractive index. It introduces a method to improve applicability by giving them other functions.
[Patent Document 1]
Japanese Patent Application Laid-Open No. 2002-277659
[Problems to be solved by the invention]
However, in the two-dimensional photonic crystal as described above, if the period for arranging the photonic crystal material and the pillar structure or the pore is determined, the wavelength range indicating the photonic band gap is limited to a narrow range. There is a problem. An object of the present invention is to provide a photonic crystal in which a wavelength region showing a photonic band gap is continuously variable over a wide range.
[0006]
[Means for Solving the Problems]
As a result of repeated studies, the inventor has discovered that a special type of photonic crystal having a specific periodic structure can be obtained by specially devising a photonic crystal. Derived.
Thus, the present invention is characterized in that the (three-dimensional) cone-shaped composite structure formed by converging the tops of a plurality of pillar-shaped structures is composed of a periodic structure arranged in a two-dimensional period. A photonic crystal is provided.
[0007]
According to the present invention, there is further provided a method for producing the photonic crystal as described above, wherein a raw material liquid containing a photosensitive functional group is coated on a light-transmitting substrate to a predetermined film thickness, dried, and then subjected to a light beam. In the manufacture of photonic crystals that are irradiated and then etched away from the non-irradiated part except the irradiated part to form the periodic structure on the light-transmitting substrate, per unit lattice on the bottom of the pillar structure on the light-transmitting substrate There is provided a method characterized in that the occupied area ratio is 30-45%.
[0008]
DETAILED DESCRIPTION OF THE INVENTION
According to the present invention, during irradiation with a light beam for producing a photonic crystal, as shown in FIGS. 1, 2, and 3, the pillar structure 3 in the unit cell 2 on the light transmissive substrate 1 is formed. By setting the occupied area ratio of the bottom surface 4 to 30 to 45%, the three-dimensional cone-shaped composite structure 3G having a shape in which the top portions 3P of the plurality of pillar-shaped structures 3 are converged (mated) is The periodic structure 30 arranged in a two-dimensional cycle on the substrate is surely obtained.
[0009]
When this periodic structure 30 is used, the wavelength region indicating the photonic band gap can be continuously changed by arbitrarily changing the light insertion position from the side surface in the z direction.
Table 1 shows that the above-mentioned technical conditions, that is, the occupied area ratio per unit cell on the bottom of the pillar structure on the light-transmitting substrate is 30 to 45%. This is a summary of experimental data indicating that a structure is obtained.
[0010]
[Table 1]

[0011]
Here, in Table 1, the film thickness is the thickness of the coating film and simultaneously corresponds to the height of the pillar structure. Further, the pillar diameter is an average value of the diameter of the pillar type structure, and in the case of *, the pillar type structure is an elliptic cylinder, and thus the minor axis and major axis of the ellipse are shown.
The area ratio is obtained by calculating the occupied area ratio per unit lattice on the bottom of the pillar structure as follows: That is, the arrangement shape from above as shown in FIG. 2 (see FIG. 10 to be described later), the length of the unit cell (the hatched portion in FIG. 2A indicates four unit cells) and the pillar diameter can be known. As shown in b), the area ratio per unit cell occupied by the cross section of the pillar structure on the bottom surface (the hatched portion in FIG. 2B represents one unit cell) was calculated.
[0012]
Types of structures include conical shapes as shown in FIGS. 1, 2 and 3, and as shown in FIG. 5, pillar-shaped structures 3 are irregular in number and the top 3P is displaced and gathered into a conical shape. There are a deformed cone type, a structure in which adjacent pillar type structures are brought into close contact as shown in FIG. 6, and a conventional parallel type as shown in FIGS. These structures can also be confirmed by observation with an electron microscope. 10 and 11 show scanning electron microscope (SEM) photographs of the conical composite structure according to the present invention.
[0013]
In the evaluation shown in Table 1, as shown in FIG. 4, the conical composite structure shown in FIG. 1, FIG. 2, and FIG. Since the wavelength range showing the photonic band gap changes continuously by changing ◎, the modified cone type can be expected to become a cone-shaped composite structure by slightly improving the conditions ○, conventional parallel type Since it shows a photonic band gap as an ordinary two-dimensional photonic crystal, it was judged as “Δ”, and in the nodule form, it was judged as “poor” because an effect as a photonic crystal could not be expected.
[0014]
In the example shown in Table 1, the conditions for light beam irradiation in photonic crystal fabrication are changed in the range of film thickness 1-30 μm, laser intensity 4-25 μJ, irradiation time 1-15 min, pillar diameter 0.5-20 μm. However, surprisingly, in any case, by setting the area ratio (occupied area ratio per unit lattice of the bottom surface of the pillar structure on the light-transmitting substrate) to 30 to 45%, the conical structure can be obtained. It is surely formed. On the other hand, if the occupied area ratio is less than 30%, there is a problem that each pillar forming the conical composite structure is thin and becomes a deformed conical type or a parallel conventional type.
On the other hand, if the area ratio exceeds 45%, there is a problem that a parallel conventional type two-dimensional photonic crystal structure is formed, or that it is in the form of an agglomerate.
[0015]
Thus, in the present invention, the conditions of the light beam irradiation to the coating film are adjusted as appropriate, the light beam irradiation is performed so that the occupied area ratio becomes 30 to 45%, and then the non-irradiated portion is formed by chemical etching. remove. Here, it is preferable to use laser interferometry for the light beam irradiation in the present invention, and the coating film is irradiated with laser light having a periodic optical intensity distribution as shown in FIG. 9 with respect to the xy plane shown in FIG. To do.
[0016]
In this laser interference method, when a photosensitizer is placed in advance in the coating film, it is necessary to use laser light corresponding to the absorption wavelength region of the photosensitizer. In particular, it is important to use a laser with excellent spatial coherence in order to irradiate light having an optical intensity distribution in which the boundary between the irradiation region and the non-irradiation region shown in FIG. 9 is clear.
[0017]
This makes it easy to adjust the occupied area ratio per unit lattice on the bottom of the pillar structure to a range of 30 to 45%, and as a result, self-organization of the pillar structure occurs, and FIG. 1 and FIG. As shown, a cone-shaped composite structure 3G is formed in which a plurality of pillar structures 3 are joined together so as to fall and gather on the beam irradiation side. FIG. 3 shows a four-unit conical composite structure, but the conical composite structure obtained by the present invention is not limited to this, and 2 to several dozen units, particularly n ² (n 2, 3 or 4) It is possible to obtain a cone-shaped structure gathered in units.
[0018]
In the present invention, as a raw material having a light-sensitive functional group for photonic crystals, for example, a so-called light-sensitive organic substance that changes to a highly chemical-resistant bond form by light, such as a C = C double bond portion, and the like. A composite material with a metal alkoxide, which is a raw material such as titania, is suitable as the high refractive index inorganic substance. Moreover, it is not limited to such an organic-inorganic composite material, In addition, it can manufacture also with an organic material, an organic polymer, etc. When an organic-inorganic composite material is used, depending on the heat treatment conditions, it is possible to burn the organic component and leave only the inorganic component.
[0019]
Furthermore, in the present invention, as a method for forming a coating film on the light-transmitting plate, dip coating, spin coating, roll coating, cast method or the like can be performed.
The chemical etching agent is not particularly limited, and may be a generally known chemical etching agent according to the type of material such as alcohol, acid, alkali such as propanol or ethoxyethanol.
[0020]
【Example】
An embodiment of the present invention will be described with reference to FIGS.
<Example 1>
Example 1 is described in No. 16 of Table 1, and is a method for producing a cone-shaped composite structure from an organic-inorganic composite material by a laser interference method, and will be described step by step below.
First step:
0.75 equivalent of dilute acidic aqueous solution is added to a mixed solution of methacryloxypropyltrimethoxysilane and phenyltrimethoxysilane and stirred (solution A). In another container, add titanium butoxide, 1/4 equivalent of methacrylic acid, and the same volume of propanol, and stir (solution B). This B solution was added to the A solution and mixed, then water and a photopolymerization initiator were added, and the mixture was further stirred for 24 hours to prepare a sol solution. A sol solution was spin-coated on a glass substrate to produce a film.
Second step:
After drying for 30 minutes at 100 ° C. where the organic solvent in the film was volatilized to solidify the photosensitive organic-inorganic composite film, coating was performed again. Thus, the coating was repeated three times to produce a gel film.
Third step:
The light-sensitive organic-inorganic composite film thus obtained is allowed to interfere with four femtosecond laser beams having an irradiation intensity of 10 μJ per beam at a wavelength of 800 nm, and light having a period of about 3 μm for 2 minutes. Irradiate.
Fourth step:
The film after laser irradiation was chemically etched with propanol for 5 minutes, and then dried by blowing dry nitrogen.
As a result, the four pillar-shaped structures 3 on the light-transmitting substrate 1 have a cone-shaped composite structure 3G in which the occupation area ratio per unit cell 2 of the bottom surface 4 is 35%, and the glass substrate as shown in FIG. A periodic structure 30 regularly arranged periodically was obtained.
In the periodic structure 30 in which the three-dimensional cone-shaped composite structures 3G are arranged in a two-dimensional period, the wavelength region indicating the photonic band gap changes continuously as described later.
5th step:
The film remaining after etching, that is, the periodic structure 30 is heat-treated. The temperature at this time was a temperature at which the organic matter in the structure remained, for example, 150 ° C.
[0021]
<Comparative example>
No. 21 in Table 1 is shown as a comparative example. After irradiating the coating film (thickness 10 μm) produced through the first step and the second step of Example 1 with 10 μJ for 10 minutes with the same laser as in the third step. Similarly, the fourth step and the fifth step were performed. As a result, a conical composite structure could not be produced, and a nodular structure as shown in FIG. 7 was obtained. At this time, the occupied area ratio per unit cell of the bottom surface 4 of the pillar-type structure 3 on the light-transmitting substrate 1 was found to be 70%.
[0022]
<Example 2>
Next, No. 6 in Table 1 is shown as a second embodiment according to the present invention.
When methacryloxypropyltrimethoxysilane is used as the raw material alkoxide for solution A and zirconium propoxide is used for solution B, a 25 μJ beam is exposed for 1 minute on the light transmissive substrate 1. The periodic structure 30 shown in FIG. 3 constituted by the conical composite structure 3G in which the area ratio per unit cell 2 on the bottom surface 4 of the pillar structure 3 of the pillar structure 3 was 35% could be produced.
The periodic structure 30 produced in the above Examples 1 and 2 can be used as, for example, a photonic crystal exhibiting a photonic band gap in different wavelength regions.
FIG. 4 is a cross-sectional explanatory view of the periodic structure 30 described above. When light passes through the surface side L2 parallel to the surface from the side surface of the periodic structure 30, the cone-shaped composite structure 3G portions applied to the light passage line L2 are arranged with the period T2, whereas the light Is parallel to the substrate side L1 from the side surface of the periodic structure 30, the cone-shaped composite structure 3G portion applied to the light passage line L1 has a period T1. Due to the difference in period, the wavelength region where the photonic band gap is formed differs greatly between light passing through L1 and light passing through L2.
T1 / T2 = 2 for the periodic structure composed of the cone-shaped composite structure made by gathering the four pillar-shaped structures obtained in Examples 1 and 2, and appears for the light passing through L1 A band gap appeared when passing through L2 in a wavelength region about twice the band gap.
[0023]
According to the present invention, the unit cell per occupied area ratio of the bottom surface of the pillar structure by 30 to 45% in the light transmitting substrate, a three-dimensional top portion of the plurality of pillar structures focused A conical composite structure is formed , and a periodic structure in which the conical composite structure is arranged in a two-dimensional period on a light-transmitting substrate is reliably obtained.
In this periodic structure, the wavelength region indicating the photonic band gap is continuously changed by arbitrarily changing the light insertion position from the side surface in the thickness direction. For example, in the case of four pillar-type structures, as described in Examples 1 and 2, the wavelength range is three times when nine pillar-type structures are gathered, and four times when 16 pillar-type structures are gathered. A band gap appears at.
The photonic crystal of the present invention comprising such a specific periodic structure can be widely applied to planar optical circuits.
[Brief description of the drawings]
FIG. 1 is a cross-sectional explanatory view of a periodic structure on a substrate showing one embodiment of the photonic crystal of the present invention.
FIG. 2 is a plan view of the photonic crystal of the present invention. (a) is from the top surface, and (b) is a view from the substrate side (bottom surface).
FIG. 3 is a three-dimensional view of the photonic crystal of the present invention.
FIG. 4 is a cross-sectional view of a photonic crystal of the present invention and an explanatory diagram of a light passage line.
FIG. 5 is a three-dimensional view of a modified cone-shaped structure configured by collecting pillar-shaped structures in a conical shape with an irregular number.
FIG. 6 is a plan view of an agglomerate structure formed by adhering adjacent pillar-type structures.
FIG. 7 is a cross-sectional view of a parallel conventional two-dimensional photonic crystal manufactured by a conventional method.
FIG. 8 is a three-dimensional view of a parallel conventional two-dimensional photonic crystal manufactured by a conventional method.
FIG. 9 is a diagram illustrating a light intensity distribution on the xy plane in FIGS. 1 and 3 of the laser light used in the present invention.
FIG. 10 is an SEM photograph of the photonic crystal of the present invention, clearly showing the state from the top surface.
FIG. 11 is an SEM photograph of the photonic crystal of the present invention, which shows that a conical structure is formed.
[Explanation of symbols]
1 Substrate 2 Unit lattice 2 (4) 4 unit lattices 2 (1) 1 unit lattice 3 Pillar structure 3P Top of pillar structure 3B Bottom of pillar structure 3G Conical composite structure 30 periods Structure T, t Structure period L Light passing line I Light intensity

Claims (2)

A photonic crystal characterized in that a cone-shaped composite structure formed by converging the tops of a plurality of pillar-shaped structures has a periodic structure arranged in a two-dimensional period . The method for producing a photonic crystal according to claim 1, wherein a raw material liquid containing a photosensitive functional group is coated on a light-transmitting substrate to a predetermined thickness and dried, and then irradiated with a light beam. Next, in the production of the photonic crystal in which the non-irradiated part except the irradiated part is etched to leave the periodic structure on the light-transmitting substrate, the ratio of the occupied area per unit lattice on the bottom of the pillar structure on the light-transmitting substrate 30 to 45%.

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