JP5263573B2 - Optical element manufacturing method and optical element - Google Patents
Optical element manufacturing method and optical element Download PDFInfo
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本発明は、パルス幅が１０-15秒〜１０-11秒の超短パルスレーザを光学高分子構造体内部に照射し、レーザ照射部の屈折率を変化させる光学素子の製造方法および光学素子に関する。 The present invention relates to an optical element manufacturing method and an optical element for irradiating an inside of an optical polymer structure with an ultrashort pulse laser having a pulse width of 10 −15 seconds to 10 −11 seconds to change the refractive index of a laser irradiation portion. .
近年、リソグラフィなどのプロセスにより光学素子を製造する方法とは別に、パルス幅が１０-15秒〜１０-11秒の超短パルスレーザ（以下、「フェムト秒レーザ」ともいう。）をガラスまたは光学高分子構造体の内部に照射し、照射部の屈折率を変化させて、たとえば回折光学素子または光導波路を有する光学素子を製造する方法が知られている。この方法は、照射するレーザをレンズなどにより集光し、焦点位置を、光学高分子構造体の内部で移動させることにより、屈折率などが変化した構造変化部を光学高分子構造体の内部の任意の部分に形成することができる（特許文献１参照）。屈折率などが異なるレーザ照射部の大きさ、形状、構造変化の程度などは、レーザの照射時間、レーザの焦点位置の移動方向とその速度、光学高分子構造体の材質、レーザのパルス幅と照射エネルギーまたはレンズの開口数などにより調整することができる。フェムト秒レーザは、チタン・サファイア結晶をレーザ媒質として得られ、その他のレーザに比べて、同じ出力であっても、単位時間・単位空間当たりの電場強度が極めて高いため、無機ガラスなどに照射することにより、新たな構造を誘起することができる。 In recent years, apart from a method of manufacturing an optical element by a process such as lithography, an ultrashort pulse laser (hereinafter also referred to as “femtosecond laser”) having a pulse width of 10 −15 seconds to 10 −11 seconds is glass or optical. A method of manufacturing an optical element having, for example, a diffractive optical element or an optical waveguide by irradiating the inside of the polymer structure and changing the refractive index of the irradiated portion is known. In this method, the laser to be irradiated is condensed by a lens or the like, and the focal position is moved inside the optical polymer structure, so that the structural change portion in which the refractive index has changed is changed inside the optical polymer structure. It can be formed in any part (see Patent Document 1). The size, shape, and degree of structural change of the laser irradiation part with different refractive index, etc. are the laser irradiation time, the moving direction and speed of the focal position of the laser, the material of the optical polymer structure, the pulse width of the laser It can be adjusted by the irradiation energy or the numerical aperture of the lens. Femtosecond lasers can be obtained using titanium or sapphire crystal as the laser medium, and irradiate inorganic glass, etc. because the electric field strength per unit time and unit space is extremely high compared to other lasers, even at the same output. Thus, a new structure can be induced.
フェムト秒レーザによる屈折率などの変化は、熱溶融と冷却による構造の変化、架橋反応による構造の変化、相分離による構造の変化などにより誘起される。たとえば、レーザの照射により、光学高分子材料が溶融し、次いで冷却することにより、照射前の配向状態から照射後の無配向状態に構造が変化する。また、レーザ照射で誘起された架橋反応により、照射前の未架橋状態が照射後、架橋状態に構造が変化する。あるいは、レーザ照射で誘起された相分離により、混合もしくは溶解状態から相分離した状態に構造が変化する。屈折率などが変化したレーザ照射部を直接、光学高分子材料などの内部に形成することができるので製造工程を短縮化し、屈折率などが変化した構造変化部を５００ｍＷ以下の低いエネルギーのレーザ照射により形成することができる。また、光学高分子材料などからなる構造体の内部に、構造変化部を形成するため、集積度の高い光学素子を得ることができる。 Changes in the refractive index due to the femtosecond laser are induced by structural changes due to thermal melting and cooling, structural changes due to cross-linking reactions, structural changes due to phase separation, and the like. For example, the optical polymer material is melted by laser irradiation and then cooled, whereby the structure changes from the alignment state before irradiation to the non-orientation state after irradiation. In addition, the structure changes to a crosslinked state after irradiation of an uncrosslinked state before irradiation by a crosslinking reaction induced by laser irradiation. Alternatively, the structure changes from a mixed or dissolved state to a phase-separated state by phase separation induced by laser irradiation. A laser irradiation part with a changed refractive index can be directly formed inside an optical polymer material, etc., so that the manufacturing process is shortened, and a structurally changed part with a changed refractive index etc. is irradiated with a low energy laser of 500 mW or less. Can be formed. In addition, since the structure change portion is formed inside the structure made of an optical polymer material or the like, an optical element with a high degree of integration can be obtained.
ところで、フェムト秒レーザにより光学素子を製造する場合、誘起する屈折率の変化が大きいことが望まれる。屈折率差が大きいと、たとえば回折光学素子において回折効率が高くなるというメリットがあるからである。ここで、屈折率の変化とは、レーザ照射部に誘起された屈折率と、未照射部の屈折率の差をいう。上記特許文献１には、光学高分子構造体として、プラスチック構造体は開示されているが、大きな屈折率差をもたらす方法は具体的に開示されていない。
本発明の課題は、光学高分子構造体の内部にフェムト秒レーザを照射することにより、照射部の屈折率を大きく変化させる光学素子の製造方法を提供することにある。また、回折効率の高い光学素子、または、例えば曲率半径が小さい時の伝播損失が小さい光導波路を有する光学素子を提供することにある。 The subject of this invention is providing the manufacturing method of the optical element which changes the refractive index of an irradiation part largely by irradiating the inside of an optical polymer structure with a femtosecond laser. Another object of the present invention is to provide an optical element having a high diffraction efficiency or an optical element having an optical waveguide with a small propagation loss when the radius of curvature is small.
本発明の光学素子の製造方法は、フェムト秒レーザを光学高分子構造体の内部に照射することにより、照射部の屈折率を変化させる光学素子の製造方法であって、フェムト秒レーザ照射前の光学高分子構造体は、密度が１ｇ／ｃｍ3以下、屈折率が１．４７以下、および線膨張係数が１×１０-4以上の少なくともいずれかの物性を満たす。 The optical element manufacturing method of the present invention is a method for manufacturing an optical element that changes the refractive index of the irradiated portion by irradiating the inside of an optical polymer structure with a femtosecond laser, and before the femtosecond laser irradiation. The optical polymer structure satisfies at least one physical property of a density of 1 g / cm 3 or less, a refractive index of 1.47 or less, and a linear expansion coefficient of 1 × 10 −4 or more.
上記光学高分子構造体はポリメチルペンテンであることが好ましく、下式（１） The optical polymer structure is preferably polymethylpentene, and has the following formula (1)
に示す構造（式中、ｎは２以上の整数）であるポリ（４−メチル−１−ペンテン）を含むことがより好ましい。 It is more preferable that poly (4-methyl-1-pentene) having the structure shown in the formula (wherein n is an integer of 2 or more) is included.
また、本発明の光学素子は、上記の製造方法により製造された光学素子であって、レーザ照射部と非照射部の屈折率の差が０．０００４以上である光学素子に関する。 The optical element of the present invention relates to an optical element manufactured by the above manufacturing method, wherein the difference in refractive index between the laser irradiation part and the non-irradiation part is 0.0004 or more.
上記照射部は、照射部の厚さ３００μｍにおける使用波長の光線の透過率が８０％以上であることが好ましい。 The irradiating part preferably has a light transmittance of a working wavelength at a thickness of 300 μm of the irradiating part of 80% or more.
フェムト秒レーザの照射により、照射部と非照射部の屈折率差が大きい光学素子を提供できる。したがって、回折光学素子の回折効率を高めることができる。 By irradiation with the femtosecond laser, an optical element having a large refractive index difference between the irradiated part and the non-irradiated part can be provided. Therefore, the diffraction efficiency of the diffractive optical element can be increased.
本発明は、パルス幅が１０-15秒〜１０-11秒のフェムト秒レーザを光学高分子構造体の内部に照射することにより、照射部の屈折率を変化させる光学素子の製造方法である。本発明者は、フェムト秒レーザ照射により光学高分子構造体の内部のレーザ照射部の屈折率が変化する理由として、照射部の密度が高くなるとの新知見を得て、本発明に至った。 The present invention is a method for manufacturing an optical element in which the refractive index of an irradiated portion is changed by irradiating the inside of an optical polymer structure with a femtosecond laser having a pulse width of 10 -15 seconds to 10 -11 seconds. The present inventor has obtained the new knowledge that the density of the irradiated portion is increased as a reason why the refractive index of the laser irradiated portion inside the optical polymer structure is changed by femtosecond laser irradiation, and has reached the present invention.
上記のようにレーザ照射後の照射部の密度が高くなる理由は、図１および図２により説明される。図１は、中心波長８００ｎｍ、パルス幅１１８×１０-15秒、パルスエネルギー７００ｎＪ、繰返し周波数１ｋＨｚ、対物レンズＮ．Ａ．（開口数）０．１３（倍率５倍）とし、対物レンズ前に５．５ｍｍ径のアパーチャを設置して、各照射対象である構造体の屈折率をｎとした時に、構造体の表面から内部へのレーザの移動が５００μｍ／ｎとなるように、光学高分子構造体の内部に集光照射し、周期Λが６μｍで一辺が２ｍｍの回折格子をステージ走査速度１ｍｍ／ｓの条件でフェムト秒レーザ照射を行なったポリメチルペンテン（ＰＭＰ）の透過電子顕微鏡（ＴＥＭ）観察画像である。また、図２は、同条件でフェムト秒レーザ照射を行なったポリメチルメタクリレート（ＰＭＭＡ）の透過電子顕微鏡観察画像である。図１および図２の観察位置は、レーザ照射した面と垂直な任意の面でスライスした断面であって、照射した面から内部へ略２００μｍ入った部分付近である。図１および図２における矢印は、フェムト秒レーザの入射方向を表す。図１において、より暗く見える部分は、フェムト秒レーザが照射された領域である。 The reason why the density of the irradiated portion after laser irradiation becomes higher as described above will be described with reference to FIGS. FIG. 1 shows a central wavelength of 800 nm, a pulse width of 118 × 10 −15 seconds, a pulse energy of 700 nJ, a repetition frequency of 1 kHz, an objective lens N.P. A. (Numerical aperture) 0.13 (magnification 5 times), an aperture having a diameter of 5.5 mm is installed in front of the objective lens, and the refractive index of each irradiation target structure is n, from the surface of the structure The optical polymer structure is focused and irradiated so that the laser movement to the inside is 500 μm / n, and a diffraction grating with a period Λ of 6 μm and a side of 2 mm is femto under the condition of a stage scanning speed of 1 mm / s. It is a transmission electron microscope (TEM) observation image of polymethylpentene (PMP) which performed second laser irradiation. FIG. 2 is a transmission electron microscope observation image of polymethyl methacrylate (PMMA) irradiated with femtosecond laser under the same conditions. The observation position in FIG. 1 and FIG. 2 is a cross-section sliced by an arbitrary plane perpendicular to the laser irradiated surface, and is in the vicinity of a portion approximately 200 μm from the irradiated surface to the inside. The arrows in FIGS. 1 and 2 represent the incident direction of the femtosecond laser. In FIG. 1, the portion that appears darker is the region irradiated with the femtosecond laser.
ＴＥＭ画像においては、明暗のコントラストは炭素原子の密度の違い、即ちポリマーの密度の違いを示し、画像が暗くなるということはポリマー密度が高くなることを意味する。図１において、ポリメチルペンテンの画像は非照射部に比し照射部が明らかに暗くなっており、従って非照射部に比し照射部は密度が高くなっていることが分かる。ここで、図２のポリメチルメタクリレートでは、図１と同様のフェムト秒レーザの軌道によりレーザ照射を行なっているが、非照射部と照射部の違いが殆ど分からない程度であり、明暗のコントラストは図１のポリメチルペンテンに比し小さいことが分かる。すなわち、ポリメチルペンテンはポリメチルメタクリレートに比し密度変化の程度が大きい。これらの結果から、レーザ照射部と非照射部の屈折率の差は、ポリメチルペンテンの方がポリメチルメタクリレートに比し大きくなるものと考えるものである。そして、上記のように照射部の密度が高くなり屈折率差が生じることから、レーザ照射部はレーザ照射前に比べて分子体積が小さくなると考えられる。 In the TEM image, the contrast between light and dark indicates the difference in density of carbon atoms, that is, the difference in density of the polymer, and the darkness of the image means that the density of the polymer is increased. In FIG. 1, in the image of polymethylpentene, it can be seen that the irradiated part is clearly darker than the non-irradiated part, and therefore the irradiated part has a higher density than the non-irradiated part. Here, in the polymethylmethacrylate shown in FIG. 2, laser irradiation is performed by the same femtosecond laser trajectory as in FIG. 1, but the difference between the non-irradiation part and the irradiation part is hardly understood, and the contrast between light and dark is It can be seen that it is smaller than the polymethylpentene of FIG. That is, polymethylpentene has a greater degree of density change than polymethyl methacrylate. From these results, it is considered that the difference in refractive index between the laser irradiated portion and the non-irradiated portion is larger in polymethylpentene than in polymethyl methacrylate. And since the density of an irradiation part becomes high as mentioned above and a refractive index difference arises, it is thought that a laser irradiation part has a molecular volume smaller than before laser irradiation.
本発明の製造方法によれば、特定の密度、屈折率、または線膨張係数を有する光学高分子構造体を用いるので、分子体積を小さくすることができ、その結果屈折率差が大きい光学素子が製造される。すなわち、本発明においては、分子体積を小さくするために、レーザ照射前の光学高分子構造体は、密度が１ｇ／ｃｍ3以下、屈折率が１．４７以下、線膨張係数が１×１０-4ｃｍ／ｃｍ℃以上の少なくともいずれかの物性を満たすものである。 According to the production method of the present invention, since an optical polymer structure having a specific density, refractive index, or linear expansion coefficient is used, the molecular volume can be reduced, and as a result, an optical element having a large refractive index difference can be obtained. Manufactured. That is, in the present invention, in order to reduce the molecular volume, the optical polymer structure before laser irradiation has a density of 1 g / cm 3 or less, a refractive index of 1.47 or less, and a linear expansion coefficient of 1 × 10 −. It satisfies at least one physical property of 4 cm / cm ° C. or higher.
本発明において、光学高分子構造体とは、該光学高分子構造体から製造される光学素子の使用波長帯域で透明なものをいい、好ましくは使用波長帯域における透過率が８０％以上である。また、その形状は、板状、膜状、特定形状（例えばレンズ形状など）、複雑な立体形状などいずれの形状のものでもよい。 In the present invention, the optical polymer structure means a transparent material in the used wavelength band of an optical element produced from the optical polymer structure, and preferably has a transmittance of 80% or more in the used wavelength band. Further, the shape may be any shape such as a plate shape, a film shape, a specific shape (for example, a lens shape), or a complicated three-dimensional shape.
本発明の第一の態様は、フェムト秒レーザ照射前の光学高分子構造体が低密度の場合である。光学高分子構造体の密度が低い方が、物理的に自由な空間が大きいので、フェムト秒レーザ照射時の熱溶融および照射後の冷却や、レーザ照射に伴う瞬間的な膨張圧縮過程などにより、圧縮され易いと考えられ、レーザ照射後の分子体積が小さくなり、その結果屈折率差を大きくすることが可能となる。なお、光学高分子構造体の密度を１ｇ／ｃｍ3以下とすると、照射部と非照射部の屈折率の差を大きくすることができる。上記密度は０．９５ｇ／ｃｍ3以下とすることがより好ましい。一方、実用に耐える材料を選択できる点や入手容易性の点で、光学高分子構造体の密度は０．８ｇ／ｃｍ3以上が好ましく、より好ましくは０．８３ｇ／ｃｍ3以上である。密度が１ｇ／ｃｍ3以下となる光学高分子構造体は、ポリメチルペンテン、シクロオレフィンポリマー、ポリビニルアセテート、ポリスチレンコポリマーなどを例示することができ、たとえば射出成形により所望の形状を付した光学高分子構造体を製造することが可能である。 The first aspect of the present invention is a case where the optical polymer structure before the femtosecond laser irradiation has a low density. The lower the density of the optical polymer structure, the larger the physical free space, so by the thermal melting at the time of femtosecond laser irradiation and cooling after irradiation, the instantaneous expansion and compression process accompanying laser irradiation, etc. It is considered that it is easily compressed, and the molecular volume after laser irradiation is reduced, and as a result, the refractive index difference can be increased. If the density of the optical polymer structure is 1 g / cm 3 or less, the difference in refractive index between the irradiated part and the non-irradiated part can be increased. The density is more preferably 0.95 g / cm 3 or less. On the other hand, the density of the optical polymer structure is preferably 0.8 g / cm 3 or more, more preferably 0.83 g / cm 3 or more, from the viewpoint that a material that can be practically used can be selected and is easily available. Examples of the optical polymer structure having a density of 1 g / cm 3 or less include polymethylpentene, cycloolefin polymer, polyvinyl acetate, polystyrene copolymer, and the like. For example, an optical polymer having a desired shape by injection molding It is possible to produce a structure.
本発明の第二の態様は、フェムト秒レーザ照射前の光学高分子構造体の線膨張係数が大きい場合である。線膨張係数が大きい場合は、フェムト秒レーザ照射時の熱溶融および照射後の冷却過程で、温度変化により縮む性質が強いために圧縮され易いと考えられる。照射部と非照射部の屈折率差を大きくする点で、光学高分子構造体の線膨張係数は１×１０-4ｃｍ／ｃｍ℃以上である。線膨張係数は、１．１７×１０-4ｃｍ／ｃｍ℃以上であることがより好ましく、また、光学素子使用時に温度変化による特性が著しく変動することを避ける点で、１×１０-3ｃｍ／ｃｍ℃以下であることが好ましい。線膨張係数が１×１０-4ｃｍ／ｃｍ℃以上となる光学高分子構造体としては、ポリメチルペンテン、ポリビニルアセテートなどを例示することができる。 The second aspect of the present invention is a case where the optical polymer structure before the femtosecond laser irradiation has a large linear expansion coefficient. When the linear expansion coefficient is large, it is considered that the thermal expansion at the time of the femtosecond laser irradiation and the cooling process after the irradiation have a strong property of shrinking due to a temperature change, so that it is likely to be compressed. The linear expansion coefficient of the optical polymer structure is 1 × 10 −4 cm / cm ° C. or more in that the difference in refractive index between the irradiated part and the non-irradiated part is increased. The linear expansion coefficient is more preferably 1.17 × 10 −4 cm / cm ° C. or more, and 1 × 10 −3 cm from the viewpoint of avoiding significant fluctuation due to temperature change when using an optical element. / Cm ° C. or less is preferable. Examples of the optical polymer structure having a linear expansion coefficient of 1 × 10 −4 cm / cm ° C. or higher include polymethylpentene and polyvinyl acetate.
本発明の第三の態様は、フェムト秒レーザ照射前の光学高分子構造体の屈折率が小さい場合である。低屈折率の光学高分子構造体は分子体積が大きいので、フェムト秒レーザ照射時の熱溶融および照射後の冷却や、レーザ照射に伴う瞬間的な膨張圧縮過程などにより、圧縮され易く、フェムト秒レーザ照射後の体積が小さくなると考えられる。屈折率が１．４７以下である。光学高分子構造体の屈折率を１．４７以下とすることにより、フェムト秒レーザ照射後、照射部と非照射部との屈折率の差を大きくすることができる。照射部と非照射部との屈折率差をより大きくする点で、光学高分子構造体の屈折率は、１．４６６以下が好ましい。一方、実用に耐える材料を選択できる点で、光学高分子構造体の屈折率は、１．３以上が好ましい。 The third aspect of the present invention is a case where the refractive index of the optical polymer structure before irradiation with the femtosecond laser is small. Since the optical polymer structure with a low refractive index has a large molecular volume, it can be easily compressed by femtosecond laser melting, cooling after irradiation, and the instantaneous expansion and compression process associated with laser irradiation. The volume after laser irradiation is considered to be small. The refractive index is 1.47 or less. By setting the refractive index of the optical polymer structure to 1.47 or less, the difference in refractive index between the irradiated part and the non-irradiated part can be increased after the femtosecond laser irradiation. The refractive index of the optical polymer structure is preferably 1.466 or less in that the difference in refractive index between the irradiated portion and the non-irradiated portion is further increased. On the other hand, the refractive index of the optical polymer structure is preferably 1.3 or more in that a material that can be practically used can be selected.
本発明において、フェムト秒レーザ照射前の光学高分子構造体は、上記密度、線膨張係数、および屈折率の少なくとも１を満足していれば、フェムト秒レーザ照射前後の屈折率の差を大きくすることが可能であり、たとえば０．０００４以上の屈折率の差とすることができる。また、上記密度、線膨張係数、および屈折率のいずれか２以上を満たす場合は、より屈折率の差を大きくすることができ、全てを満たす場合は、フェムト秒レーザ照射前後の屈折率の差を確実に生じさせることができ、たとえば、０．０００８以上の屈折率の差とすることができる。 In the present invention, if the optical polymer structure before the femtosecond laser irradiation satisfies at least one of the above density, linear expansion coefficient, and refractive index, the difference in refractive index before and after the femtosecond laser irradiation is increased. For example, the refractive index difference may be 0.0004 or more. Moreover, when satisfying any two or more of the above-mentioned density, linear expansion coefficient, and refractive index, the difference in refractive index can be further increased, and when satisfying all, the difference in refractive index between before and after femtosecond laser irradiation. For example, a difference in refractive index of 0.0008 or more.
屈折率が１．４７以下である光学高分子構造体を構成する材料としては、下記に詳細に説明するポリメチルペテンのほか、ジエチレングリコールビスアリルカーボネート（屈折率１．４５０２〜１．４５１７）、テトラフルオロエチレン−ヘキサフルオロプロピレン共重合体（屈折率１．３３８）、ポリ４フッ化エチレン（屈折率１．３５〜１．３８）、ポリトリフロロクロロエチレン（屈折率１．４２〜１．４３）、ポリフッ化ビニリデン（屈折率１．４２）、セルロースアセテートブチレート（屈折率１．４６〜１．４７）、ポリブチルアクリレート（屈折率１．４６３１）、ポリビニルアセテート（屈折率１．４６６５）などが好適である。これらの材料は、１種または２種以上を混合して用いることが可能であるが、屈折率の維持等の点から１種で用いることが好ましい。これらの材料は、レーザ照射後、照射部と非照射部との間で大きな屈折率差を得る点で、光学高分子構造体を構成する材料中に、好ましくは８０質量％以上、より好ましくは９０質量％以上含まれる。また、かかる材料の中でも、ポリメチルペンテン（以下、「ＰＭＰ」ともいう。）は、ポリメチルメタクリレート（以下、「ＰＭＭＡ」ともいう。）またはポリカーボネート（以下、「ＰＣ」ともいう。）に比べて、レーザ照射後、照射部と非照射部との間で大きな屈折率差が得られる点で好ましい。また、これらの１．４７以下の屈折率を示すポリマーは、比較的物質の密度が低く、そのため体積が外部の刺激により容易に増減し、大きな屈折率変化を誘起できる。とくに、ポリメチルペンテンは、著しく密度が低く、低屈折率であり、かつ線膨張係数が大きいので、かかる挙動を起こしやすい点で好ましい。 Materials constituting the optical polymer structure having a refractive index of 1.47 or less include polymethylpetene described in detail below, diethylene glycol bisallyl carbonate (refractive index: 1.4502 to 1.4517), tetra Fluoroethylene-hexafluoropropylene copolymer (refractive index 1.338), polytetrafluoroethylene (refractive index 1.35 to 1.38), polytrifluorochloroethylene (refractive index 1.42 to 1.43) , Polyvinylidene fluoride (refractive index 1.42), cellulose acetate butyrate (refractive index 1.46 to 1.47), polybutyl acrylate (refractive index 1.4631), polyvinyl acetate (refractive index 1.4665), etc. Is preferred. These materials can be used alone or in combination of two or more. However, it is preferable to use one material from the viewpoint of maintaining the refractive index. In terms of obtaining a large refractive index difference between the irradiated part and the non-irradiated part after laser irradiation, these materials are preferably 80% by mass or more, more preferably in the material constituting the optical polymer structure. 90% by mass or more is contained. Among such materials, polymethylpentene (hereinafter also referred to as “PMP”) is more than polymethyl methacrylate (hereinafter also referred to as “PMMA”) or polycarbonate (hereinafter also referred to as “PC”). In view of obtaining a large refractive index difference between the irradiated portion and the non-irradiated portion after the laser irradiation. In addition, these polymers having a refractive index of 1.47 or less have a relatively low material density, so that the volume can be easily increased or decreased by an external stimulus, and a large refractive index change can be induced. In particular, polymethylpentene is preferable because it has a remarkably low density, a low refractive index, and a large coefficient of linear expansion, and thus tends to cause such behavior.
ポリメチルペンテンは、メチルペンテンをチーグラー−ナッタ触媒またはカチオン性触媒を用いて重合することにより形成することができる熱可塑性樹脂である。チーグラー−ナッタ触媒により重合したポリメチルペンテンは、立体構造の規則性が高く、結晶性を有するが、カチオン重合すると、不規則構造の無定形ポリマーとなる。メチルペンテンには、非置換および置換体として、３−メチル−１−ペンテン、２−メチル−１−ペンテン、２−メチル−２−ペンテン、３−メチル−ｃｉｓ−２−ペンテン、３−メチル−ｔｒａｎｓ−２−ペンテン、４−メチル−ｃｉｓ−２−ペンテン、４−メチル−１−ペンテン、２，４−ジフェニル−４−メチル−１−ペンテンなどがある。 Polymethylpentene is a thermoplastic resin that can be formed by polymerizing methylpentene using a Ziegler-Natta catalyst or a cationic catalyst. Polymethylpentene polymerized by a Ziegler-Natta catalyst has a high regularity of steric structure and crystallinity. However, when cationic polymerization is performed, it becomes an amorphous polymer having an irregular structure. Methylpentene includes 3-methyl-1-pentene, 2-methyl-1-pentene, 2-methyl-2-pentene, 3-methyl-cis-2-pentene, 3-methyl- trans-2-pentene, 4-methyl-cis-2-pentene, 4-methyl-1-pentene, 2,4-diphenyl-4-methyl-1-pentene, and the like.
ポリ（４−メチル−１−ペンテン）は、融点が２２０℃〜２４０℃であり、熱安定性に優れ、可視光線透過率が９０％以上の透明性の良好なポリマーであり、可視光線だけでなく、紫外線領域（波長３００ｎｍ〜４００ｎｍ）でも優れた光線透過率を有し、耐熱老化性と気体透過性に優れた材料であるため、本発明の光学高分子構造体に適した材料である。ポリ（４−メチル−１−ペンテン）は、つぎの式（１）に示す構造（ｎは２以上の整数）を有するが、４−メチル−１−ペンテンと、３質量％〜５質量％のＣ6〜Ｃ16の直鎖α−オレフィンとを共重合させたコポリマーも有効に使用することができる。とくに、チーグラーナッタ触媒を用いて重合したポリ（４−メチル−１−ペンテン）は、屈折率が１．４６３〜１．４６６、密度が０．８３ｇ／ｃｍ3であり、光学高分子構造体の材料として好適である。 Poly (4-methyl-1-pentene) has a melting point of 220 ° C. to 240 ° C., is excellent in thermal stability, is a transparent polymer with a visible light transmittance of 90% or more, and is only visible light. In addition, it is a material suitable for the optical polymer structure of the present invention because it has excellent light transmittance even in the ultraviolet region (wavelength of 300 nm to 400 nm) and is excellent in heat aging resistance and gas permeability. Poly (4-methyl-1-pentene) has a structure represented by the following formula (1) (n is an integer of 2 or more), but 4-methyl-1-pentene and 3% by mass to 5% by mass. Copolymers obtained by copolymerizing C 6 -C 16 linear α-olefins can also be used effectively. In particular, poly (4-methyl-1-pentene) polymerized using a Ziegler-Natta catalyst has a refractive index of 1.463 to 1.466 and a density of 0.83 g / cm 3 . Suitable as a material.
上記密度、線膨張係数、および屈折率の少なくともいずれかを満たす材料を用いて、例えば射出成形を行なうことにより所望の形状を有する光学高分子構造体を製造することができる。 An optical polymer structure having a desired shape can be produced, for example, by injection molding using a material satisfying at least one of the density, linear expansion coefficient, and refractive index.
上記光学高分子構造体にフェムト秒レーザを照射して、照射部の屈折率を変化させるためのレーザ照射条件は、照射により上記光学高分子構造体の内部の所望位置が熱溶融もしくは、光学高分子構造体を構成する高分子の主鎖や側鎖あるいはその両方が一部的に切断されるサブアブレーションなどにより屈折率変化を起こすようなエネルギーであって、光散乱や光吸収を起こすような損傷変化を起こさない状態までのエネルギーを付与できるよう調整すればよい。 The laser irradiation conditions for irradiating the optical polymer structure with femtosecond laser to change the refractive index of the irradiated part are as follows. Energy that causes a change in refractive index due to sub-ablation in which the main chain and / or side chain of the polymer that constitutes the molecular structure is partially cut, and that causes light scattering and light absorption Adjustment may be made so that energy up to a state where no damage change occurs can be applied.
上記密度、線膨張係数、および屈折率の少なくともいずれかを満たす材料を含む光学高分子構造体の内部にフェムト秒レーザを照射することにより形成される光学素子は、フェムト秒レーザの照射部と非照射部との屈折率差が、０．０００４以上であり、好ましくは０．０００７以上、より好ましくは０．０００８以上であり、フェムト秒レーザ照射後の屈折率が大きくなることが好ましい。したがって、高回折効率を有する回折光学素子、または例えば曲率半径が小さい時の伝播損失が小さい光導波路を有する優れた光学素子を提供することができる。光導波路において小さい曲率半径を有する形状とすることが要される場合は、本発明における光学素子は上記のように照射後の屈折率が大きくなるので、小さい曲率半径を有する形状とする場合の伝播素子の低減効果を向上させることができる。光学素子における照射部は、レーザ加工により製造された光学素子の光利用効率が高められ、光導波路における光の伝播損失を低減する点で、照射部の厚さ３００μｍにおける使用波長帯域の光線の透過率が８０％以上のものが好ましく、９０％以上のものがより好ましい。また、光学高分子構造体は、構造体内部を外部から視認することができ、フェムト秒レーザの照射位置および焦点位置を容易に調整することが可能となり、レーザ加工性を向上することができる点で、照射部の厚さ１ｍｍにおける可視光線透過率が８０％以上の態様が好ましく、９０％以上の態様がより好ましい。ここに、可視光線は、波長４００ｎｍ〜８００ｎｍの電磁波をいう。また、使用波長帯域の光線は、可視光線に限らず、波長８００ｎｍ〜１７００ｎｍの近赤外光線などでも構わない。なお、照射部の厚さは、レーザが照射された際に、光学高分子構造体において屈折率の変化が誘起されるレーザ進入方向の長さ（改質厚）をいう。 An optical element formed by irradiating a femtosecond laser inside an optical polymer structure containing a material satisfying at least one of the density, the linear expansion coefficient, and the refractive index is different from a part irradiated with a femtosecond laser. The difference in refractive index from the irradiated portion is 0.0004 or more, preferably 0.0007 or more, more preferably 0.0008 or more, and the refractive index after femtosecond laser irradiation is preferably increased. Therefore, it is possible to provide an excellent optical element having a diffractive optical element having a high diffraction efficiency or an optical waveguide having a small propagation loss when the radius of curvature is small, for example. When the optical waveguide needs to have a shape with a small radius of curvature, the optical element in the present invention has a large refractive index after irradiation as described above. The effect of reducing the element can be improved. The irradiation part of the optical element transmits light in the used wavelength band when the irradiation part has a thickness of 300 μm in that the light use efficiency of the optical element manufactured by laser processing is increased and the propagation loss of light in the optical waveguide is reduced. The rate is preferably 80% or more, more preferably 90% or more. In addition, the optical polymer structure can visually recognize the inside of the structure from the outside, can easily adjust the irradiation position and the focal position of the femtosecond laser, and can improve the laser workability. Thus, an aspect in which the visible light transmittance at a thickness of 1 mm of the irradiated portion is 80% or more is preferable, and an aspect in which 90% or more is more preferable. Here, visible light refers to electromagnetic waves having a wavelength of 400 nm to 800 nm. Further, the light in the used wavelength band is not limited to visible light, but may be near infrared light having a wavelength of 800 nm to 1700 nm. Note that the thickness of the irradiated portion refers to the length (modified thickness) in the laser entrance direction in which a change in refractive index is induced in the optical polymer structure when the laser is irradiated.
上記光学高分子構造体に含まれるその他の材料としては、該構造体の密度、線膨張係数、屈折率などに影響を及ぼさない限り特に限定されるものではなく、たとえば、射出成形時の離型性を良好とする点から、高級脂肪酸などの離型剤などを添加したり、色調を変える場合は、顔料などの着色剤などを添加することができる。 The other materials included in the optical polymer structure are not particularly limited as long as the density, linear expansion coefficient, refractive index, etc. of the structure are not affected. For example, release during injection molding From the viewpoint of improving the properties, when adding a release agent such as a higher fatty acid or changing the color tone, a colorant such as a pigment can be added.
以下、実施例を挙げて本発明をより詳細に説明するが、本発明はこれらに限定されるものではない。 EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated in detail, this invention is not limited to these.
（実施例１）
まず、１．レーザ照射方法、２．回折特性の測定方法と屈折率差の計算方法、３．レーザ照射による屈折率変化部位の透過率の測定方法について述べる。
Example 1
First, 1. 1. Laser irradiation method 2. a method for measuring diffraction characteristics and a method for calculating a difference in refractive index; A method for measuring the transmittance of the refractive index changing portion by laser irradiation will be described.
１．レーザ照射方法
フェムト秒レーザは、中心波長８００ｎｍ、パルス幅１１８×１０-15秒、繰返し周波数１ｋＨｚとした。また、Ｎ．Ａ．（開口数）０．１３の対物レンズ（倍率５倍）を使用し、対物レンズ前に５．５ｍｍ径のアパーチャを設置し、各材料の屈折率をｎとしたときに、構造体の表面から内部への移動が５００μｍ／ｎとなるように、光学高分子構造体の内部に集光照射し、周期Λが１０μｍで、一辺が１ｍｍの回折格子を作製した。また、ステージ速度は１ｍｍ／sで走査した。
1. Laser irradiation method The femtosecond laser had a center wavelength of 800 nm, a pulse width of 118 × 10 −15 seconds, and a repetition frequency of 1 kHz. N. A. (Numerical aperture) 0.13 objective lens (5x magnification), 5.5mm diameter aperture is installed in front of the objective lens, and the refractive index of each material is n. From the surface of the structure The inside of the optical polymer structure was condensed and irradiated so that the inward movement was 500 μm / n, and a diffraction grating having a period Λ of 10 μm and a side of 1 mm was produced. The stage speed was scanned at 1 mm / s.
２．回折特性の測定方法と、フェムト秒レーザの照射により誘起される屈折率差Δｎの計算方法
回折特性として、回折効率と回折角を測定した。すなわち、フェムト秒レーザにより形成した周期Λが１０μｍで、一辺が１ｍｍの回折格子を、回折格子に垂直な方向からブラッグ角θBだけ傾けて測定した。測定に使用するレーザは、Ｈｅ−Ｎｅレーザ（波長λ＝６３２．８ｎｍ）とし、ビーム径φ０．５ｍｍで入射した。その後、回折格子から５００ｍｍの位置にスクリーンを置き、０次光と１次光の間隔から回折角を算出した。
2. Method for Measuring Diffraction Characteristics and Calculation Method for Refractive Index Difference Δn Induced by Femtosecond Laser Irradiation As diffraction characteristics, diffraction efficiency and diffraction angle were measured. That is, the measurement was performed by tilting a diffraction grating formed by a femtosecond laser with a period Λ of 10 μm and a side of 1 mm from a direction perpendicular to the diffraction grating by a Bragg angle θ B. The laser used for the measurement was a He—Ne laser (wavelength λ = 632.8 nm), and was incident with a beam diameter of 0.5 mm. Thereafter, a screen was placed at a position 500 mm from the diffraction grating, and the diffraction angle was calculated from the interval between the 0th order light and the 1st order light.
本実施例の場合、２ΛｓｉｎθB＝λの関係よりθB＝１．８°となるため、回折格子を傾ける角度は１．８°とし、また５００ｍｍ離れた位置での０次光と１次光の距離が３１．７ｍｍ程度であることから、周期Λ＝１０μｍでの回折光を確認するようにした。一方、屈折率差Δｎは、回折効率から導出した。すなわち、測定した１次回折効率をη1、屈折率差をΔｎ、屈折率変化部の長さをＬ、測定時の波長をλ、ブラッグ回折角をθBとして、つぎの式（２）から屈折率差Δｎを求めた。 In the case of the present embodiment, θ B = 1.8 ° because of the relationship 2Λsin θ B = λ, so the angle at which the diffraction grating is tilted is 1.8 °, and the 0th order light and the 1st order light at positions 500 mm apart. Since the distance is about 31.7 mm, diffracted light with a period Λ = 10 μm was confirmed. On the other hand, the refractive index difference Δn was derived from the diffraction efficiency. That is, when the measured first-order diffraction efficiency is η 1 , the refractive index difference is Δn, the length of the refractive index changing portion is L, the wavelength at the time of measurement is λ, and the Bragg diffraction angle is θ B , The refractive index difference Δn was determined.
改質厚Ｌは透過型顕微鏡で観察することにより測定した。ここで、回折効率からのΔｎの導出に本式（２）を用いているのは、本実施例では、厚みを表すパラメータＱ値が１０に近い値であり、いわゆる「厚い」回折格子であり、回折格子の透過率が９０％以上と吸収がほとんどないためである。なお、Ｑ値は、つぎの式（３）のように表される。 The modified thickness L was measured by observing with a transmission microscope. Here, this equation (2) is used for derivation of Δn from the diffraction efficiency in this embodiment, the parameter Q value representing the thickness is a value close to 10, which is a so-called “thick” diffraction grating. This is because the transmittance of the diffraction grating is 90% or more and there is almost no absorption. The Q value is expressed as the following equation (3).
３．レーザ照射による屈折率変化部位の透過率の測定方法
透過率は、波長６３２．８ｎｍの可視光線による光学高分子構造体への透過後の光量に対し、厚さ１８０μｍ〜３１０μｍの回折格子を透過した後、回折分岐した次数光をすべて足し合わせた光量の比率で表した。
3. Method for Measuring Transmittance of Refractive Index Change Site by Laser Irradiation Transmittance was transmitted through a diffraction grating having a thickness of 180 μm to 310 μm with respect to the amount of light after passing through the optical polymer structure by visible light having a wavelength of 632.8 nm. After that, it was expressed as a ratio of the amount of light obtained by adding all the orders of light that were diffracted and branched.
本実施例においては、屈折率が１．４６３である結晶性ポリ（４−メチル−１−ペンテン）（ＰＭＰ）（三井化学社製ＴＰＸ型式ＲＴ１８）を用いて、射出成形により１００ｍｍ×１００ｍｍ、厚さ２ｍｍの直方体を形成した後、これを切断して、各大きさが１０ｍｍ×１０ｍｍ、厚さ２ｍｍの直方体の光学高分子構造体を形成した。つぎに、光学高分子構造体の最も面積の広い面の一方から、該光学高分子構造体の内部に、加工面でのレーザパルスエネルギーが５００ｎＪとなるように、フェムト秒レーザを照射した。照射後、得られた光学素子のレーザ照射部での屈折率差Δｎ、照射部の厚さ３００μｍにおける波長６３２．８ｎｍの可視光線透過率と回折効率を評価した。屈折率差Δｎは、改質厚Ｌ＝３００μｍに基づき、前述の式（２）により算出した。表１に、光学高分子構造体の屈折率、レーザ照射後に得られた光学素子の照射部における屈折率差Δｎ、改質厚Ｌ、Ｑ値、回折効率と波長６３２．８ｎｍの可視光線透過率を示す。 In this example, a crystalline poly (4-methyl-1-pentene) (PMP) having a refractive index of 1.463 (TPX model RT18 manufactured by Mitsui Chemicals, Inc.) was used for injection molding, and the thickness was 100 mm × 100 mm. After forming a rectangular parallelepiped having a thickness of 2 mm, this was cut to form a rectangular parallelepiped optical polymer structure having a size of 10 mm × 10 mm and a thickness of 2 mm. Next, a femtosecond laser was irradiated from one of the surfaces having the largest area of the optical polymer structure into the optical polymer structure so that the laser pulse energy on the processed surface was 500 nJ. After the irradiation, the refractive index difference Δn at the laser irradiation portion of the obtained optical element, the visible light transmittance at a wavelength of 632.8 nm and the diffraction efficiency at the irradiation portion thickness of 300 μm were evaluated. The refractive index difference Δn was calculated by the above formula (2) based on the modified thickness L = 300 μm. Table 1 shows the refractive index of the optical polymer structure, the refractive index difference Δn, the modified thickness L, the Q value, the diffraction efficiency, and the visible light transmittance at a wavelength of 632.8 nm in the irradiated portion of the optical element obtained after laser irradiation. Indicates.
（比較例１〜５）
実施例１における、ＰＭＰの代わりに、一般的な光学高分子材料として、つぎのポリマーを使用した以外は、実施例１と同様にして光学高分子構造体を形成し、実施例１と同様にしてフェムト秒レーザを照射することにより光学素子を製造した。なお、比較例５では、ＰＳの損傷を避けるため、レーザパルスエネルギーを４００ｎＪとした。表１に、光学高分子構造体の屈折率、レーザ照射後に得られた光学素子の照射部における屈折率差Δｎ、改質厚Ｌ、Ｑ値、回折効率と波長６３２．８ｎｍの可視光線透過率を示す。
(Comparative Examples 1-5)
An optical polymer structure was formed in the same manner as in Example 1 except that the following polymer was used as a general optical polymer material instead of PMP in Example 1. An optical element was manufactured by irradiating a femtosecond laser. In Comparative Example 5, the laser pulse energy was 400 nJ in order to avoid PS damage. Table 1 shows the refractive index of the optical polymer structure, the refractive index difference Δn, the modified thickness L, the Q value, the diffraction efficiency, and the visible light transmittance at a wavelength of 632.8 nm in the irradiated portion of the optical element obtained after laser irradiation. Indicates.
比較例１；ポリメチルメタクリレート（ＰＭＭＡ）（三菱レーヨン社製アクリライト型式０００）
比較例２；ポリアクリルイミド（ＰＭＭＩ）（ダイセルデグザ社製ＰＬＥＸＩＭＩＤ型式８８０５）
比較例３；環状ポリオレフィン（ＣＯＰ１）（日本ゼオン社製ＺＥＯＮＥＸ型式４８０）
比較例４；ポリカーボネート（ＰＣ）（帝人社製パンライト型式ＡＤ５５０３）
比較例５；ポリスチレン（ＰＳ）（ＰＳジャパン社製ＰＳＪポリスチレン型式ＳＧＰ１０-Ｋ２７）
表１の結果から明らかなとおり、実施例１では、ＰＭＰからなる光学高分子構造体の屈折率（１．４６３）が１．４７以下であるため、照射部における屈折率差Δｎが９．９×１０-4、回折効率が４５．１％、レーザ照射部の透過率が９０％以上であった。したがって、比較例１〜５に比べて、屈折率差Δｎで３〜１４倍、回折効率で１０〜１７０倍大きくなり、回折効率の高い光学素子を提供できることがわかった。
Comparative Example 1; polymethyl methacrylate (PMMA) (Acrylite model 000 manufactured by Mitsubishi Rayon Co., Ltd.)
Comparative Example 2: Polyacrylimide (PMMI) (Pleximid Model 8805 manufactured by Daicel Degussa)
Comparative Example 3: Cyclic polyolefin (COP1) (ZEONEX model 480 manufactured by Zeon Corporation)
Comparative Example 4: Polycarbonate (PC) (Teijin Ltd. Panlite Model AD5503)
Comparative Example 5: Polystyrene (PS) (PSJ polystyrene model SGP10-K27 manufactured by PS Japan)
As is clear from the results in Table 1, in Example 1, the refractive index difference Δn in the irradiated portion is 9.9 because the refractive index (1.463) of the optical polymer structure made of PMP is 1.47 or less. × 10 -4 , the diffraction efficiency was 45.1%, and the transmittance of the laser irradiation part was 90% or more. Therefore, it was found that the refractive index difference Δn was 3 to 14 times larger and the diffraction efficiency was 10 to 170 times larger than Comparative Examples 1 to 5, and an optical element with high diffraction efficiency could be provided.
（実施例２）
本実施例においては、密度が０．９５ｇ／ｃｍ3である環状ポリオレフィン（日本ゼオン社製、ＺＥＯＮＥＸ型式３３０Ｒ、表２中にＣＯＰ２と表記する）により実施例１と同様に光学高分子構造体を形成した。フェムト秒レーザの条件は、中心波長８００ｎｍ、パルス幅１１８×１０-15秒、繰返し周波数１ｋＨｚとした。また、Ｎ．Ａ．（開口数）０．２５の対物レンズ（倍率１０倍）を使用し、対物レンズ前に５．５ｍｍ径のアパーチャを設置し、各材料の屈折率をｎとしたときに、構造体の表面から内部への移動が５００μｍ／ｎとなるように、光学高分子構造体の内部に集光照射し、周期Λが１０μｍで、一辺が１ｍｍの回折格子を作製した。また、ステージ速度は１ｍｍ／sで走査した。つぎに、光学高分子構造体の内部に、加工面でのレーザパルスエネルギーが５００ｎＪとなるように、フェムト秒レーザを照射した。照射後、得られた光学素子のレーザ照射部での屈折率差Δｎ、照射部の厚さ１８０μｍにおける波長６３２．８ｎｍの可視光線透過率、回折効率を評価した。
(Example 2)
In this example, an optical polymer structure was formed in the same manner as in Example 1 by using a cyclic polyolefin having a density of 0.95 g / cm 3 (manufactured by Nippon Zeon Co., Ltd., ZEONEX model 330R, expressed as COP2 in Table 2). Formed. The femtosecond laser conditions were a center wavelength of 800 nm, a pulse width of 118 × 10 −15 seconds, and a repetition frequency of 1 kHz. N. A. When a numerical aperture of 0.25 objective lens (10x magnification) is used, an aperture with a diameter of 5.5 mm is installed in front of the objective lens, and the refractive index of each material is n, from the surface of the structure The inside of the optical polymer structure was condensed and irradiated so that the inward movement was 500 μm / n, and a diffraction grating having a period Λ of 10 μm and a side of 1 mm was produced. The stage speed was scanned at 1 mm / s. Next, a femtosecond laser was irradiated into the optical polymer structure so that the laser pulse energy on the processed surface was 500 nJ. After the irradiation, the refractive index difference Δn at the laser irradiation portion of the obtained optical element, the visible light transmittance at a wavelength of 632.8 nm and the diffraction efficiency at the thickness of the irradiation portion of 180 μm were evaluated.
屈折率差Δｎは、前述の回折効率と観察された改質厚Ｌ＝１８０μｍに基づき、ブラッグ回折効率式により算出した。表２に、光学高分子構造体の密度、屈折率、線膨張係数、レーザ照射後に得られた光学素子の照射部における屈折率差Δｎ、改質厚Ｌ、Ｑ値、回折効率と波長６３２．８ｎｍの可視光線透過率を示す。 The refractive index difference Δn was calculated by the Bragg diffraction efficiency equation based on the above-described diffraction efficiency and the observed modified thickness L = 180 μm. Table 2 shows the density, refractive index, linear expansion coefficient of the optical polymer structure, refractive index difference Δn, modified thickness L, Q value, diffraction efficiency and wavelength 632. The visible light transmittance of 8 nm is shown.
（比較例６）
実施例２における、環状ポリオレフィンＺＥＯＮＥＸ型式３３０Ｒの代わりに、密度が１．０１ｇ／ｃｍ3の環状ポリオレフィンＺＥＯＮＥＸ型式４８０（日本ゼオン社製、表２中にＣＯＰ１と表記する）を使用した以外は、実施例2と同様にして光学高分子構造体を形成し、実施例２と同様にしてフェムト秒レーザを照射することにより光学素子を製造した。表２に、光学高分子構造体の密度、屈折率、線膨張係数、レーザ照射後に得られた光学素子の照射部における屈折率差Δｎ、改質厚Ｌ、Ｑ値、回折効率と波長６３２．８ｎｍの可視光線透過率を示す。
(Comparative Example 6)
In Example 2, instead of the cyclic polyolefin ZEONEX model 330R, a cyclic polyolefin ZEONEX model 480 having a density of 1.01 g / cm 3 (made by Nippon Zeon Co., Ltd., expressed as COP1 in Table 2) was used. An optical polymer structure was formed in the same manner as in Example 2, and an optical element was produced by irradiating a femtosecond laser in the same manner as in Example 2. Table 2 shows the density, refractive index, linear expansion coefficient of the optical polymer structure, refractive index difference Δn, modified thickness L, Q value, diffraction efficiency and wavelength 632. The visible light transmittance of 8 nm is shown.
表２の結果から明らかなとおり、実施例２においては比較例６の場合よりも、照射部における屈折率差Δｎが大きく７．２×１０-4であった。これら２つの材料は組成が同じであるので、密度の違いによりΔｎが変化し、低密度であるＺＥＯＮＥＸ型式３３０Ｒの方が高いΔｎを誘起できることが確認できる。 As apparent from the results in Table 2, in Example 2, the refractive index difference Δn in the irradiated portion was larger than that in Comparative Example 6 and was 7.2 × 10 −4 . Since these two materials have the same composition, Δn changes depending on the density, and it can be confirmed that the low density ZEONEX model 330R can induce higher Δn.
今回開示された実施の形態および実施例はすべての点で例示であって制限的なものではないと考えられるべきである。本発明の範囲は上記した説明ではなくて特許請求の範囲によって示され、特許請求の範囲と均等の意味および範囲内でのすべての変更が含まれることが意図される。 It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.
回折効率が高い光学素子または例えば曲率半径が小さい時の伝播損失が小さい光導波路を有する光学素子を提供することができる。 An optical element having a high diffraction efficiency or an optical waveguide having a small propagation loss when the radius of curvature is small can be provided.
Claims (7)
フェムト秒レーザ照射前の前記光学高分子構造体は、密度が１ｇ／ｃｍ3以下である、光学素子の製造方法。 A method of manufacturing an optical element that changes the refractive index of an irradiated portion by irradiating a femtosecond laser with a pulse width of 10 −15 seconds to 10 −11 seconds inside an optical polymer structure,
The said optical polymer structure before femtosecond laser irradiation is a manufacturing method of an optical element whose density is 1 g / cm < 3 > or less.
フェムト秒レーザ照射前の前記光学高分子構造体は、屈折率が１．４７以下である、光学素子の製造方法。 A method of manufacturing an optical element that changes the refractive index of an irradiated portion by irradiating a femtosecond laser with a pulse width of 10 −15 seconds to 10 −11 seconds inside an optical polymer structure,
The said optical polymer structure before femtosecond laser irradiation is a manufacturing method of the optical element whose refractive index is 1.47 or less.
フェムト秒レーザ照射前の前記光学高分子構造体は、線膨張係数が１×１０-4ｃｍ／ｃｍ℃以上である、光学素子の製造方法。 A method of manufacturing an optical element that changes the refractive index of an irradiated portion by irradiating a femtosecond laser with a pulse width of 10 −15 seconds to 10 −11 seconds inside an optical polymer structure,
The method for producing an optical element, wherein the optical polymer structure before the femtosecond laser irradiation has a linear expansion coefficient of 1 × 10 −4 cm / cm ° C. or more.
フェムト秒レーザ照射部と非照射部の屈折率の差が０．０００４以上である光学素子。 An optical element manufactured by the method for manufacturing an optical element according to claim 1,
An optical element in which the difference in refractive index between the femtosecond laser irradiation part and the non-irradiation part is 0.0004 or more.
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| R250 | Receipt of annual fees |
Free format text: JAPANESE INTERMEDIATE CODE: R250 |
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| LAPS | Cancellation because of no payment of annual fees |