JP2007255948A - Electric field sensor - Google Patents
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本発明は電界センサに関する。詳しくは電気光学効果を有する材料の電界による屈折率変化を表面プラズモンの共鳴状態又は導波路モード光波の励起状態の変化により検出する電界センサに関する。 The present invention relates to an electric field sensor. More specifically, the present invention relates to an electric field sensor that detects a change in refractive index due to an electric field of a material having an electro-optic effect by a change in a resonance state of surface plasmons or an excitation state of a waveguide mode light wave.
電界が印加された際に電気光学結晶（以下ＥＯ結晶という）中に生じる電気光学効果（以下ＥＯ効果という）を利用した電界センサは非接触による電界の検出が可能であり、広く研究が行われ、一部は実用化もされている。現在用いられている電界センサは、例えば、ＥＯ効果により生じる光の位相遅れを偏光状態の変化として検出している。ＥＯ効果を利用した電界センサには、（１）オシロスコープの信号計測用非接触プローブ、（２）Ｆｓ（Ｆｅｍｔｓｅｃｏｎｄ）パルスレーザーと組み合わせた集積回路の高速非接触サンプリング、（３）ＴＨｚ（Ｔｅｒａｈｅｒｔｚ）帯などの光波計測、のような応用分野がある。この中で、（１）は計測器メーカーを中心にオシロスコープなどのプローブとして実用化されている。また、アンテナ、給電などの分野でも応用が検討されている。（２）では、ＥＯ結晶を回路上に搭載してビームをスキャンすることにより空間的な情報を得るなどの手法が用いられている。そのため、プローブを任意の位置に自由に動かすことはできない。（３）は（２）とほぼ同じ使い方であるが、近年重要性を増している分野である。ＴＨｚイメージングなどの分野へ応用すれば、生体、安全など関連分野への波及効果は大きい。（非特許文献１参照） An electric field sensor using an electro-optic effect (hereinafter referred to as an EO effect) generated in an electro-optic crystal (hereinafter referred to as an EO crystal) when an electric field is applied can detect the electric field in a non-contact manner and has been extensively studied. Some have been put to practical use. Currently used electric field sensors detect, for example, a phase delay of light caused by the EO effect as a change in polarization state. The electric field sensor using the EO effect includes (1) a non-contact probe for signal measurement of an oscilloscope, (2) high-speed non-contact sampling of an integrated circuit combined with an Fs (Femsecond) pulse laser, and (3) a THz (Terahertz) band. There are application fields such as optical wave measurement. Among these, (1) is put into practical use as a probe such as an oscilloscope mainly by measuring instrument manufacturers. Applications are also being studied in the fields of antennas and power feeding. In (2), a method of obtaining spatial information by mounting an EO crystal on a circuit and scanning a beam is used. Therefore, the probe cannot be freely moved to an arbitrary position. (3) is almost the same usage as (2), but is an increasingly important field in recent years. If applied to fields such as THz imaging, the ripple effect on related fields such as living bodies and safety is great. (See Non-Patent Document 1)
他方、表面プラズモンを用いるセンサについては、全反射減衰法を用いた表面プラズモン共鳴測定を利用した手法が用いられているが、プローブ構造の制限が大きく、ＤＮＡのハイブリッド化を検出できるような高い感度を保ったまま、ミクロンサイズあるいはそれ以下のサイズへ微小化することは難しかった。発明者はナノメートルサイズの金属微粒子に励起される局在化プラズモン共鳴を用いて、高い感度を保ったまま、センシング部分のミクロンサイズへの微小化を実現した。（特許文献１参照） On the other hand, for sensors using surface plasmons, a technique using surface plasmon resonance measurement using the total reflection attenuation method is used, but the sensitivity of the probe structure is so high that DNA hybridization can be detected. It was difficult to reduce the size to a micron size or smaller while maintaining the above. The inventor has realized the miniaturization of the sensing portion to a micron size while maintaining high sensitivity using localized plasmon resonance excited by nanometer-sized metal fine particles. (See Patent Document 1)
しかしながら、ＥＯ効果を用いるセンサにおいて高い感度を得るためには、光路長を大きくする必要があるため、高品質の大きなＥＯ結晶を用いる必要がある。そのため、膜厚数１０μｍ〜数１００μｍの結晶が必要である。また、ＥＯ効果により生じる屈折率変化は僅かであるため、従来の電界センサでは、微小な屈折率変化を検出するために、ＥＯ効果を示す非線形光学結晶に対して入射した光の位相変化を利用したり、干渉計を利用したりして感度の向上をはかっている。また、走査光ビームをスキャンすることにより空間的な情報を得ることもできるが、位相差板や偏光板などの光学部品が必要であったり、光導波路を作製したりしなければならず、測定の手軽さやコストの点で満足できるものではなかった。また、プローブを自由に動かすことができない、光学系が単純ではない、などの問題があった。 However, in order to obtain high sensitivity in a sensor using the EO effect, it is necessary to increase the optical path length, and thus it is necessary to use a high quality large EO crystal. Therefore, a crystal having a film thickness of several tens of μm to several hundreds of μm is necessary. In addition, since the refractive index change caused by the EO effect is small, the conventional electric field sensor uses the phase change of the incident light to the nonlinear optical crystal exhibiting the EO effect in order to detect the minute refractive index change. Or using an interferometer to improve sensitivity. Spatial information can also be obtained by scanning a scanning light beam, but optical components such as a phase difference plate and a polarizing plate are required, and an optical waveguide must be produced. Was not satisfactory in terms of convenience and cost. In addition, there are problems that the probe cannot be moved freely and the optical system is not simple.
ところで、発明者達による表面プラズモン共鳴の研究から、表面プラズモン共鳴（局在化表面プラズモン共鳴を含む）の共鳴条件や全反射時のエバネッセント光で励起された導波路モード光波の励起条件が周辺媒質の屈折率変化に敏感であることがわかってきた。このことに着目すれば、ＥＯ効果を示す媒質の屈折率変化を単純な反射率変化として検出できる電界センサを実現できる可能性がある。 By the way, from the surface plasmon resonance research by the inventors, the resonance conditions of surface plasmon resonance (including localized surface plasmon resonance) and the excitation conditions of waveguide mode light waves excited by evanescent light during total reflection are It has been found to be sensitive to refractive index changes. If attention is paid to this, there is a possibility that an electric field sensor capable of detecting a change in the refractive index of a medium exhibiting the EO effect as a simple change in reflectivity may be realized.
ここでいう表面プラズモン共鳴とは、電子のプラズマ波が表面の境界条件の特殊性により光波と相互作用を起こす現象をいう。例えば全反射減衰法（ＡＴＲ法；Ａｔｔｅｎｕａｔｅｄ ｔｏｔａｌ ｒｅｆｌｅｃｔｉｏｎ法）における表面プラズモン共鳴や金属ナノ微粒子、ナノ構造、粗い金属表面、島状金属における局在化表面プラズモン共鳴などが生じる。共鳴条件は、表面付近の誘電率や誘電体の吸着・結合状態に敏感に反応するという特徴を持つ。他方、導波路モード光波とは、表面プラズモンと同様に全反射減衰法により生じるモードである。全反射減衰法に用いるプリズム底面に１０ｎｍから８０ｎｍの金属薄膜を堆積し、さらにその表面に堆積した誘電体薄膜（厚さは波長程度かそれ以上）中に生じるモードで、導波路モード光波が入射光と共鳴することにより反射率のディップ（鋭い減衰）を生じる。 Surface plasmon resonance as used herein refers to a phenomenon in which an electron plasma wave interacts with a light wave due to the special surface boundary conditions. For example, surface plasmon resonance in the total reflection attenuation method (ATR method: Attenuated total reflection method), localized surface plasmon resonance in a metal nanoparticle, nanostructure, rough metal surface, or island metal occurs. The resonance condition has a characteristic that it reacts sensitively to the dielectric constant near the surface and the adsorption / bonding state of the dielectric. On the other hand, the waveguide mode light wave is a mode generated by the total reflection attenuation method, like the surface plasmon. A metallic thin film with a thickness of 10 to 80 nm is deposited on the bottom of the prism used in the total reflection attenuation method, and a waveguide mode light wave is incident on the surface of the dielectric thin film (thickness is about the wavelength or more). Resonance with light causes a reflectivity dip.
全反射減衰法における表面プラズモン共鳴および導波路モード光波との共鳴は同じ光学配置で観測されるが、入射角が異なる。また、表面プラズモン共鳴を起こすのは、ｐ−偏光の入射光のみであるが、導波路モード光波との共鳴はｐ−偏光およびｓ−偏光の入射光で起こり、金属表面上の誘電体薄膜の膜厚により異なるが、厚い場合には複数の入射角で共鳴を起こす。 Surface plasmon resonance and resonance with waveguide mode light waves in the total reflection attenuation method are observed with the same optical arrangement, but with different incident angles. Further, surface plasmon resonance occurs only in p-polarized incident light, but resonance with waveguide mode light waves occurs in p-polarized light and s-polarized incident light. Depending on the film thickness, resonance occurs at a plurality of incident angles when the film is thick.
本発明は、電気光学効果を用いる電界センサに表面プラズモン共鳴（局在化表面プラズモン共鳴を含む）や導波路モード光波の励起を応用することにより、高感度、小型、低コストの電界センサを提供することを目的とする。 The present invention provides a high-sensitivity, small-sized, and low-cost electric field sensor by applying surface plasmon resonance (including localized surface plasmon resonance) and waveguide mode light wave excitation to an electric field sensor using an electro-optic effect. The purpose is to do.
上記課題を解決するために、請求項１に記載の電界センサＥＳ１は、例えば図１に示すように、プリズム１の面に、金属層２を形成し、金属層２の表面に電気光学効果を有する高分子などの電気光学薄膜３を形成し、プリズム１の面で全反射される全反射減衰法を用いて、電界印加による電気光学薄膜３の屈折率の変化による金属層２表面に励起される表面プラズモンの共鳴状態の変化又は電気光学薄膜３内に励起される導波路モード光波の励起状態の変化から電界を検出する。 In order to solve the above-mentioned problem, an electric field sensor ES1 according to claim 1 has a metal layer 2 formed on the surface of the prism 1, for example, as shown in FIG. An electro-optic thin film 3 made of polymer or the like is formed, and is excited on the surface of the metal layer 2 by a change in the refractive index of the electro-optic thin film 3 by applying an electric field, using a total reflection attenuation method that is totally reflected by the surface of the prism 1 The electric field is detected from the change in the resonance state of the surface plasmon or the change in the excitation state of the waveguide mode light wave excited in the electro-optic thin film 3.
ここにおいて、金属層には、金属膜、金属粒子層等が含まれる。また、必ずしも純金属である必要はなく。不純物や結晶欠陥があっても良い。また、金属層には合金層が含まれるものとする。また、電気光学薄膜にはポッケルス効果、カー効果等を示す薄膜が含まれるが、その他屈折率が変わる薄膜であれば良い。また、電界の検出には、電界有無、電位高低の検出だけでなく、定量的な電位測定も含まれる。このように構成すると、ＥＯ効果を用いる電界センサに表面プラズモン共鳴や導波路モード光波の励起を応用することにより、高感度、小型、低コストの電界センサを提供できる。特に、導波路モード光波を用いると、高感度で実用的な電界センサの提供に好適である。 Here, the metal layer includes a metal film, a metal particle layer, and the like. Moreover, it is not necessarily required to be a pure metal. There may be impurities and crystal defects. The metal layer includes an alloy layer. In addition, the electro-optic thin film includes a thin film exhibiting the Pockels effect, the Kerr effect, and the like, but any other thin film having a different refractive index may be used. In addition, the detection of an electric field includes not only the presence / absence of an electric field and the detection of electric potential level, but also quantitative electric potential measurement. With this configuration, an electric field sensor with high sensitivity, small size, and low cost can be provided by applying surface plasmon resonance or waveguide mode light wave excitation to an electric field sensor using the EO effect. In particular, the use of a waveguide mode light wave is suitable for providing a highly sensitive and practical electric field sensor.
また、請求項２に記載の発明は、請求項１に記載の電界センサにおいて、表面プラズモンの共鳴状態の変化又は導波路モード光波の励起状態の変化を、全反射減衰法における反射光５の強度、位相又は共鳴波長の変化により検出する。このように構成すると、電界の変化を高感度に検出でき好適である。 According to a second aspect of the present invention, in the electric field sensor according to the first aspect, the change in the resonance state of the surface plasmon or the change in the excitation state of the waveguide mode light wave is caused by the intensity of the reflected light 5 in the total reflection attenuation method. Detect by phase or resonance wavelength change. If comprised in this way, the change of an electric field can be detected with high sensitivity, and it is suitable.
また、請求項３に記載の電界センサは、例えば図９（ｂ）に示すように、光ファイバ１１端面又は光透過性基板表面に、局在化表面プラズモンが励起される寸法の金属微粒子層１４ａ又は金属グレーティング層を形成し、金属微粒子層１４ａ又は金属グレーティング層の表面に電気光学効果を有する電気光学薄膜１５を形成し、金属微粒子層１４ａ又は金属グレーティング層からの反射光１７、透過光又は散乱光を用いて、電界印加による電気光学薄膜１５の屈折率の変化による局在化表面プラズモンの共鳴状態の変化から電界を検出する。 Further, as shown in FIG. 9B, for example, the electric field sensor according to claim 3 has a metal fine particle layer 14a having a dimension that allows localized surface plasmons to be excited on the end face of the optical fiber 11 or the surface of the light transmitting substrate. Alternatively, a metal grating layer is formed, an electro-optic thin film 15 having an electro-optic effect is formed on the surface of the metal fine particle layer 14a or the metal grating layer, and reflected light 17, transmitted light or scattered from the metal fine particle layer 14a or the metal grating layer. Using light, the electric field is detected from the change in the resonance state of the localized surface plasmon caused by the change in the refractive index of the electro-optic thin film 15 due to the application of the electric field.
ここにおいて、局在化表面プラズモンが励起される寸法の金属微粒子層１４ａとは直径１５ｎｍから１５０ｎｍの金属の微粒子を表面に単層、あるいは数層に固定化したものをいい、局在化表面プラズモンが励起される寸法の金属グレーティング層とは金属の表面に光の波長程度（１００ｎｍから１５００ｎｍ）の周期的な凹凸構造の持つものをいう。このように構成すると、ＥＯ効果を用いる電界センサに局在化表面プラズモン共鳴を応用することにより、高感度、小型、低コストの電界センサを提供できる。特に、光ファイバ端面に形成したセンサは、微小領域の電界の検出に好適である。 Here, the metal fine particle layer 14a having such a size that the localized surface plasmon is excited means a metal fine particle having a diameter of 15 nm to 150 nm fixed to a single layer or several layers on the surface, and the localized surface plasmon. The metal grating layer having a size that excites is a layer having a periodic concavo-convex structure of about the wavelength of light (100 nm to 1500 nm) on the metal surface. If comprised in this way, a highly sensitive, small size, and low-cost electric field sensor can be provided by applying localized surface plasmon resonance to the electric field sensor using the EO effect. In particular, the sensor formed on the end face of the optical fiber is suitable for detecting an electric field in a minute region.
また、請求項４に記載の電界センサは、例えば図９（ａ）に示すように、光ファイバ１１端面又は光透過性基板表面に、局在化表面プラズモンが励起される寸法の金属微粒子１４を分散した電気光学効果を有する電気光学薄膜１５を形成し、金属微粒子１４からの反射光１７、透過光又は散乱光を用いて、電界印加による電気光学薄膜１５の屈折率の変化による局在化表面プラズモンの共鳴状態の変化から電界を検出する。 Further, in the electric field sensor according to claim 4, for example, as shown in FIG. 9 (a), metal fine particles 14 having a size capable of exciting localized surface plasmons are provided on the end face of the optical fiber 11 or the surface of the light transmitting substrate. A localized surface is formed by changing the refractive index of the electro-optic thin film 15 by applying an electric field using the reflected light 17, transmitted light or scattered light from the metal fine particles 14 by forming the electro-optic thin film 15 having a dispersed electro-optic effect. The electric field is detected from the change in the resonance state of the plasmon.
ここにおいて、局在化表面プラズモンが励起される寸法の金属微粒子１４とは直径１５ｎｍから１５０ｎｍの金属の微粒子をいう。また、金属微粒子の分散は、典型的には電気光学効果を有する電気光学薄膜中で一様に分散しているが、これに限られず、例えば光ファイバ端面側に偏って分散していても良い。このように構成すると、ＥＯ効果を用いる電界センサに局在化表面プラズモン共鳴を応用することにより、高感度、小型、低コストの電界センサを提供できる。特に、光ファイバ端面に形成したセンサは、微小領域の電界の検出に好適である。 Here, the metal fine particle 14 having such a size that the localized surface plasmon is excited means a metal fine particle having a diameter of 15 nm to 150 nm. Further, the dispersion of the metal fine particles is typically uniformly dispersed in the electro-optic thin film having the electro-optic effect, but is not limited thereto, and may be, for example, biased toward the end face of the optical fiber. . If comprised in this way, a highly sensitive, small size, and low-cost electric field sensor can be provided by applying localized surface plasmon resonance to the electric field sensor using the EO effect. In particular, the sensor formed on the end face of the optical fiber is suitable for detecting an electric field in a minute region.
また、請求項５に記載の発明は、請求項３又は請求項４に記載の電界センサにおいて、前記局在化表面プラズモンの共鳴状態の変化を、反射光、透過光又は散乱光の強度、位相又は共鳴波長の変化により検出する。このように構成すると、電界の変化を高感度に検出でき好適である。 Further, the invention according to claim 5 is the electric field sensor according to claim 3 or claim 4, wherein the change in the resonance state of the localized surface plasmon is represented by the intensity, phase of reflected light, transmitted light or scattered light. Or it detects by the change of resonance wavelength. If comprised in this way, the change of an electric field can be detected with high sensitivity, and it is suitable.
また、請求項６に記載の電界センシング装置は、請求項１乃至請求項５のいずれか１項に記載の電界センサＥＳ１と、表面プラズモン、導波路モード光波又は局在化表面プラズモンを励起する光を発光する光源と、電界を検出する光検出器６と、光検出器６で検出された電界の状態を記憶し、表示する処理装置とを備える。ここにおいて、処理装置とはコンピュータをいい、ここでは記憶手段、表示手段を有する。このように構成すると、ＥＯ効果を用いる電界センサに表面プラズモン共鳴等を応用することにより、高感度、小型、低コストの電界センシング装置を提供できる。 Further, the electric field sensing device according to claim 6 is a light that excites the electric field sensor ES1 according to any one of claims 1 to 5 and a surface plasmon, a waveguide mode light wave, or a localized surface plasmon. , A light detector 6 for detecting an electric field, and a processing device for storing and displaying the state of the electric field detected by the light detector 6. Here, the processing device refers to a computer, and here has storage means and display means. With this configuration, it is possible to provide an electric field sensing device with high sensitivity, small size, and low cost by applying surface plasmon resonance or the like to an electric field sensor using the EO effect.
また、請求項７に記載の発明は、請求項６に記載の電界センシング装置において、例えば図７に示すように、プリズム１の面を平行に移動可能である。このように構成すると、集積回路などの平面に構成された回路における電界の検出に好適である。 Further, according to a seventh aspect of the present invention, in the electric field sensing device according to the sixth aspect, as shown in FIG. 7, for example, the surface of the prism 1 can be moved in parallel. Such a configuration is suitable for detection of an electric field in a circuit configured on a plane such as an integrated circuit.
また、請求項８に記載の電界センシング方法は、例えば図４に示すように、請求項１に記載の電界センサを準備する（Ｓ００１）工程と、電界センサＥＳ１の金属層２内に表面プラズモンを又は電気光学薄膜３内に導波路モード光波を励起して（Ｓ００２）、全反射減衰法を用いて反射光を検出する（Ｓ００３）工程と、電界センサＥＳ１に電界を印加する（Ｓ００４）工程と、電界センサＥＳ１の金属層２内に表面プラズモンを又は電気光学薄膜３内に導波路モード光波を励起して（Ｓ００５）、全反射減衰法を用いて反射光の変化を検出する（Ｓ００６）工程と、反射光５の変化から電界を検出する（Ｓ００７）工程とを備える。 In addition, in the electric field sensing method according to claim 8, for example, as shown in FIG. 4, the step of preparing the electric field sensor according to claim 1 (S001), and surface plasmon in the metal layer 2 of the electric field sensor ES1 Alternatively, a step of exciting a waveguide mode light wave in the electro-optic thin film 3 (S002) and detecting reflected light using the total reflection attenuation method (S003), and a step of applying an electric field to the electric field sensor ES1 (S004) The step of exciting the surface plasmon in the metal layer 2 of the electric field sensor ES1 or the waveguide mode light wave in the electro-optic thin film 3 (S005), and detecting the change of the reflected light using the total reflection attenuation method (S006). And a step of detecting an electric field from the change of the reflected light 5 (S007).
ここにおいて、反射光の変化とは典型的には工程Ｓ００３と工程Ｓ００６との間での反射光の変化をいうが、工程Ｓ００３で一度電界の無い状態での反射光を検出しておけば、工程Ｓ００４における電界や位置を変化させて工程Ｓ００４〜工程Ｓ００７を繰り返し行ない、その間での反射光の変化を追跡すれば、電圧値を追跡できるので、電界や位置を変化させた場合の反射光の変化を含めても良い。また、電界の検出とは、典型的には電界の有無の検出をいうが、電圧値の検出も含む。電界の有無の検出は反射光の変化の検出をもって行っても良い。また、電圧値の検出は反射光の変化から演算により行っても良く、キャリブレーション値と比較して行っても良い。また、工程Ｓ００２における、表面プラズモン又は導波路モード光波の励起を工程Ｓ００５まで持続した状態で、工程Ｓ００４で電界センサＥＳ１を電界内に出し入れしても良い。このように構成すると、ＥＯ効果を用いる電界センサに表面プラズモン共鳴や導波路モード光波の励起を応用することにより、高感度、小領域、低コストの電界センシング方法を提供できる。 Here, the change in reflected light typically refers to a change in reflected light between steps S003 and S006, but once the reflected light in the absence of an electric field is detected in step S003, If the electric field and position in step S004 are changed and steps S004 to S007 are repeated, and the change in reflected light between them is tracked, the voltage value can be traced. Therefore, the reflected light when the electric field and position are changed Changes may be included. The detection of an electric field typically means detection of the presence or absence of an electric field, but also includes detection of a voltage value. The presence or absence of an electric field may be detected by detecting a change in reflected light. Further, the voltage value may be detected by calculation from a change in reflected light, or may be compared with a calibration value. Further, the electric field sensor ES1 may be taken into and out of the electric field in step S004 while the surface plasmon or waveguide mode light wave excitation in step S002 is continued until step S005. With this configuration, a high-sensitivity, small-area, and low-cost electric field sensing method can be provided by applying surface plasmon resonance and waveguide mode light wave excitation to an electric field sensor using the EO effect.
また、請求項９に記載の電界センシング方法は、例えば図１１に示すように、請求項３に記載の電界センサＥＳ３を準備する工程（Ｓ１０１）と、電界センサＥＳ３の金属微粒子層１４ａ又は金属グレーティング層の表面に局在化表面プラズモンを励起して（Ｓ１０２）、金属微粒子層１４ａ又は金属グレーティング層からの反射光１７、透過光又は散乱光を検出する（Ｓ１０３）工程と、電界センサＥＳ３に電界を印加する（Ｓ１０４）工程と、電界センサＥＳ３の金属微粒子層１４ａ又は金属グレーティング層の表面に局在化表面プラズモンを励起して（Ｓ１０５）、金属微粒子層１４ａ又は金属グレーティング層からの反射光５、透過光又は散乱光の変化を検出する（Ｓ１０５）工程と、反射光５、透過光又は散乱光の変化から電界を検出する（Ｓ１０７）工程とを備える。 Further, the electric field sensing method according to claim 9 includes a step (S101) of preparing the electric field sensor ES3 according to claim 3, and a metal fine particle layer 14a or a metal grating of the electric field sensor ES3, as shown in FIG. A step of exciting localized surface plasmons on the surface of the layer (S102), detecting reflected light 17, transmitted light or scattered light from the metal fine particle layer 14a or the metal grating layer (S103), and applying an electric field to the electric field sensor ES3. Is applied (S104), and localized surface plasmons are excited on the surface of the metal fine particle layer 14a or the metal grating layer of the electric field sensor ES3 (S105), and the reflected light 5 from the metal fine particle layer 14a or the metal grating layer 5 is excited. , Detecting a change in transmitted light or scattered light (S105), and an electric field from the change in reflected light 5, transmitted light or scattered light. And a output for (S107) process.
ここにおいて、工程Ｓ１０２における、局在化表面プラズモンの励起を工程Ｓ１０５まで持続した状態で、工程Ｓ１０４で電界センサＥＳ３を電界内に出し入れしても良い。このように構成すると、ＥＯ効果を用いる電界センサに局在化表面プラズモン共鳴を応用することにより、高感度、小領域、低コストの電界センシング方法を提供できる。 Here, the electric field sensor ES3 may be taken into and out of the electric field in step S104 while the localized surface plasmon excitation in step S102 is continued until step S105. If comprised in this way, a highly sensitive, small area | region, and low-cost electric field sensing method can be provided by applying localized surface plasmon resonance to the electric field sensor using EO effect.
また、請求項１０に記載の電界センシング方法は、例えば図１１に示すように、請求項４に記載の電界センサＥＳ２を準備する工程（Ｓ１０１）と、電界センサＥＳ２の金属微粒子１４の表面に局在化表面プラズモンを励起して（Ｓ１０２）、金属微粒子１４からの反射光１７、透過光又は散乱光を検出する（Ｓ１０３）工程と、電界センサＥＳ２に電界を印加する（Ｓ１０４）工程と電界センサＥＳ２の金属微粒子１４の表面に局在化表面プラズモンを励起して（Ｓ１０５）、金属微粒子１４からの反射光１７、透過光又は散乱光の変化を検出する（Ｓ１０６）工程と、反射光１７、透過光又は散乱光の変化から電界を検出する（Ｓ１０７）工程とを備える。 In addition, the electric field sensing method according to claim 10 includes a step (S101) of preparing the electric field sensor ES2 according to claim 4 and a surface of the metal fine particle 14 of the electric field sensor ES2, as shown in FIG. Exciting the localized surface plasmon (S102), detecting the reflected light 17, transmitted light or scattered light from the metal fine particles 14 (S103), applying an electric field to the electric field sensor ES2 (S104) and the electric field sensor A step of exciting localized surface plasmons on the surface of the metal fine particle 14 of ES2 (S105), detecting a change in reflected light 17, transmitted light or scattered light from the metal fine particle 14 (S106); A step of detecting an electric field from a change in transmitted light or scattered light (S107).
ここにおいて、工程Ｓ１０２における、局在化表面プラズモンの励起を工程Ｓ１０５まで持続した状態で、工程Ｓ１０４で電界センサＥＳ１を電界内に出し入れしても良い。このように構成すると、ＥＯ効果を用いる電界センサに局在化表面プラズモン共鳴を応用することにより、高感度、小領域、低コストの電界センシング方法を提供できる。 Here, the electric field sensor ES1 may be taken into and out of the electric field in step S104 while the excitation of the localized surface plasmon in step S102 is continued until step S105. If comprised in this way, a highly sensitive, small area | region, and low-cost electric field sensing method can be provided by applying localized surface plasmon resonance to the electric field sensor using EO effect.
本発明によれば、電気光学効果を用いる電界センサに表面プラズモン共鳴や導波路モード光波の励起を応用することにより、高感度、小型、低コストの電界センサを提供できる。 According to the present invention, an electric field sensor with high sensitivity, small size, and low cost can be provided by applying surface plasmon resonance or waveguide mode light wave excitation to an electric field sensor using an electro-optic effect.
以下に図面に基づき本発明の実施の形態について説明する。 Embodiments of the present invention will be described below with reference to the drawings.
〔第１の実施の形態〕
第１の実施の形態は、全反射減衰（ＡＴＲ）法を用い、表面プラズモンの共鳴状態の変化から電界を検出する例を説明する。
[First Embodiment]
In the first embodiment, an example in which an electric field is detected from a change in the resonance state of surface plasmon using the total reflection attenuation (ATR) method will be described.
図１に、第１の実施の形態における電界センサＥＳ１の構成例を示す。図１において、プリズム１の底面に金（Ａｕ）等の金属薄膜２を形成し、その上にＥＯ効果を有する高分子（以後、ＥＯポリマーという）等の電気光学薄膜３を塗布等により形成する。金属薄膜２の厚さは例えば３０〜８０ｎｍである。ＥＯポリマーなどの電気光学薄膜３の厚さは１００ｎｍ〜数１０μｍ程度と従来のＥＯセンサに用いられる電気光学結晶より薄い。電界センサＥＳ１は、これらプリズム１、金属薄膜２、電気光学薄膜３により構成される。測定はＡＴＲ法で行う。入射光４をプリズム１を介して金属薄膜２に入射し、金属薄膜２からの全反射による反射光５を光検出器６により検出する。また、電界センサＥＳ１のプリズム１の底面に平行に基板７が配置され、電界センサＥＳ１と基板７の間隔は例えば２０μｍである。基板７に搭載された２つの平行な信号線８ａ、８ｂ間に電圧が印加されると、電気光学薄膜３が電界内に置かれる。 FIG. 1 shows a configuration example of the electric field sensor ES1 in the first embodiment. In FIG. 1, a metal thin film 2 such as gold (Au) is formed on the bottom surface of a prism 1, and an electro-optic thin film 3 such as a polymer having an EO effect (hereinafter referred to as EO polymer) is formed thereon by coating or the like. . The thickness of the metal thin film 2 is, for example, 30 to 80 nm. The thickness of the electro-optic thin film 3 such as EO polymer is about 100 nm to several tens of μm, which is thinner than the electro-optic crystal used in the conventional EO sensor. The electric field sensor ES1 includes the prism 1, the metal thin film 2, and the electro-optic thin film 3. Measurement is performed by the ATR method. Incident light 4 is incident on the metal thin film 2 through the prism 1, and reflected light 5 due to total reflection from the metal thin film 2 is detected by the photodetector 6. Further, the substrate 7 is arranged in parallel to the bottom surface of the prism 1 of the electric field sensor ES1, and the distance between the electric field sensor ES1 and the substrate 7 is, for example, 20 μm. When a voltage is applied between two parallel signal lines 8a and 8b mounted on the substrate 7, the electro-optic thin film 3 is placed in an electric field.
図２は表面プラズモンによる共鳴吸収を説明するための図である。横軸に光入射角θ（ｄｅｇ）、縦軸に反射率を示す。全反射条件で単色光４を入射（入射角θ）するとある共鳴角θＲで金属薄膜２中に電子波の一種である表面プラズモンが励起される。金属薄膜２に表面プラズモンが励起されると、エバネッセント波が放射され、特定の周波数の光がプラズモンに吸収されて共鳴吸収が生じる。金属薄膜２の表面にＥＯポリマー３が存在する場合は、ＥＯポリマー３の屈折率の影響を受けて共鳴角がシフトする。この状態で、例えば、基板７に搭載された信号線８ａ、８ｂ間に電位差が生じて、ＥＯポリマー３中に電界が印加されると、ＥＯポリマー３中の屈折率が僅かに変化し、これが、共鳴状態の変化となって現れ、その結果、共鳴波長、反射光５の位相、反射率や偏光状態が変化する。 FIG. 2 is a diagram for explaining resonance absorption by surface plasmons. The horizontal axis represents the light incident angle θ (deg), and the vertical axis represents the reflectance. Surface plasmon is a kind of electron waves in the metal thin film 2 of monochromatic light 4 incident at (incident angle theta) Then there resonance angle theta R is excited by the total reflection condition. When surface plasmon is excited in the metal thin film 2, an evanescent wave is emitted, and light of a specific frequency is absorbed by the plasmon, thereby causing resonance absorption. When the EO polymer 3 is present on the surface of the metal thin film 2, the resonance angle is shifted under the influence of the refractive index of the EO polymer 3. In this state, for example, when a potential difference is generated between the signal lines 8a and 8b mounted on the substrate 7 and an electric field is applied to the EO polymer 3, the refractive index in the EO polymer 3 slightly changes. As a result, the resonance state, the phase of the reflected light 5, the reflectivity, and the polarization state change.
図３に本実施の形態における検出器６から検出された検出信号（以下、ＥＯ信号という）の例を示す。図３において、上欄に信号線８ａ、８ｂ間の電界（Ｖ／μｍ）、下欄にＥＯ信号（ｍＶ）を示す。横軸は時間（ｍｓ）である。実験では、金属薄膜２は膜厚５０ｎｍ±５ｎｍの金薄膜、ＥＯポリマー３は膜厚１．１μｍの高分子薄膜（ＰＭＭＡ−ＤＲ１）で、波長６３５ｎｍの単色光を使用し、基板７はＥＯセンサ面から２０μｍ離して平行に保持し、１ｍｍ間隔の２本の信号線８ａ、８ｂ間にＴＴＬレベル（０〜５Ｖ）の電圧を印加し、約０〜１０ｍＶのＥＯ信号が得られた。 FIG. 3 shows an example of a detection signal (hereinafter referred to as an EO signal) detected from the detector 6 in the present embodiment. In FIG. 3, the upper column shows the electric field (V / μm) between the signal lines 8a and 8b, and the lower column shows the EO signal (mV). The horizontal axis is time (ms). In the experiment, the metal thin film 2 is a gold thin film with a film thickness of 50 nm ± 5 nm, the EO polymer 3 is a polymer thin film (PMMA-DR1) with a film thickness of 1.1 μm, and monochromatic light with a wavelength of 635 nm is used, and the substrate 7 is an EO sensor. An EO signal of about 0 to 10 mV was obtained by applying a voltage of TTL level (0 to 5 V) between the two signal lines 8 a and 8 b spaced at a distance of 20 μm from the surface and held in parallel.
図４に本実施の形態におけるセンシング方法の処理フロー例を示す。まず、電界センサＥＳ１を準備する（Ｓ００１）。次に、電界センサＥＳ１の金属層２内に表面プラズモンを又は電気光学薄膜３内に導波路モード光波を励起して（Ｓ００２）、全反射減衰法を用いて反射光を検出する（Ｓ００３）。次に、電界センサＥＳ１に電界を印加する（Ｓ００４）。次に、電界センサＥＳ１の金属層２内に表面プラズモンを又は電気光学薄膜３内に導波路モード光波を励起して（Ｓ００５）、全反射減衰法を用いて反射光５の変化を検出する（Ｓ００６）。次に、工程Ｓ００３と工程Ｓ００６における反射光５の変化から電界を検出する（Ｓ００７）。なお、工程Ｓ００２における、表面プラズモンを又は導波路モード光波の励起を工程Ｓ００５まで持続した状態で、工程Ｓ００４で電界センサＥＳ１を電界内に出し入れしても良い。 FIG. 4 shows an example of a processing flow of the sensing method in the present embodiment. First, the electric field sensor ES1 is prepared (S001). Next, surface plasmons are excited in the metal layer 2 of the electric field sensor ES1 or waveguide mode light waves are excited in the electro-optic thin film 3 (S002), and the reflected light is detected using the total reflection attenuation method (S003). Next, an electric field is applied to the electric field sensor ES1 (S004). Next, a surface plasmon is excited in the metal layer 2 of the electric field sensor ES1 or a waveguide mode light wave is excited in the electro-optic thin film 3 (S005), and a change in the reflected light 5 is detected using a total reflection attenuation method ( S006). Next, an electric field is detected from the change of the reflected light 5 in steps S003 and S006 (S007). Note that the electric field sensor ES1 may be taken in and out of the electric field in step S004 in a state where the excitation of the surface plasmon or the waveguide mode light wave in step S002 is continued until step S005.
ここでは、表面プラズモン共鳴について、反射光５の強度の変化を検出する例について説明したが、位相の変化、共鳴波長の変化を検出することも可能である。 Here, an example of detecting the change in the intensity of the reflected light 5 with respect to the surface plasmon resonance has been described, but it is also possible to detect a change in phase and a change in resonance wavelength.
〔第２の実施の形態〕
第２の実施の形態は、全反射減衰（ＡＴＲ）法を用い、導波路モード光波の励起状態の変化から電界を検出する例を説明する。
[Second Embodiment]
In the second embodiment, an example in which an electric field is detected from a change in the excited state of a waveguide mode light wave using the total reflection attenuation (ATR) method will be described.
図５は導波路モード光波における吸収を説明するための図である。図５（ａ）に波長６３５ｎｍにおけるＡＴＲ配置における反射率の入射角依存性の例を示す。縦軸に反射率、横軸に入射光の入射角θを示す。プリズムは屈折率１．５の直角プリズムを仮定し、ＥＯポリマー３の屈折率は１．５とした。ＥＯポリマー３が薄い場合（約８０ｎｍ以下）では、金属薄膜２に表面プラズモンのみが励起される。ＥＯポリマー３が厚い場合（約０．５μｍ以上）には、金属薄膜２に表面プラズモンが励起される他に、ＥＯポリマー３内に導波路モード光波が励起される。表面プラズモン共鳴の共鳴条件に対応して全反射時のエバネッセント光により導波路モード光波が励起される。図５（ｂ）にＥＯポリマー３内の導波路モード光波を概念的に示す。ＥＯポリマー３内に境界面を反射鏡とする共振波が励起され、反射光５に吸収が表れる。まず、表面プラズモンの共鳴角θＲが現れる。そして、導波路モード光波における基本波（入射角θ１）による吸収が表面プラズモンによる吸収の低入射角側に現れ、ＥＯポリマー３の膜厚が厚くなるにつれて、順次、２次（入射角θ２）、３次（入射角θ３、図示しない）の導波路モードがさらに低入射角側に観測される。 FIG. 5 is a diagram for explaining absorption in a waveguide mode light wave. FIG. 5A shows an example of the incident angle dependence of the reflectance in the ATR arrangement at a wavelength of 635 nm. The vertical axis represents the reflectance, and the horizontal axis represents the incident angle θ of the incident light. The prism is assumed to be a right-angle prism having a refractive index of 1.5, and the refractive index of the EO polymer 3 is 1.5. When the EO polymer 3 is thin (about 80 nm or less), only surface plasmons are excited in the metal thin film 2. When the EO polymer 3 is thick (about 0.5 μm or more), in addition to surface plasmons being excited in the metal thin film 2, waveguide mode light waves are excited in the EO polymer 3. A waveguide mode light wave is excited by the evanescent light at the time of total reflection corresponding to the resonance condition of the surface plasmon resonance. FIG. 5B conceptually shows a waveguide mode light wave in the EO polymer 3. A resonant wave having a boundary surface as a reflecting mirror is excited in the EO polymer 3, and absorption appears in the reflected light 5. First, the surface plasmon resonance angle θ R appears. Then, the absorption by the fundamental wave (incident angle θ1) in the waveguide mode light wave appears on the low incident angle side of the absorption by the surface plasmon, and the secondary (incident angle θ2) sequentially as the film thickness of the EO polymer 3 increases. A third-order (incident angle θ3, not shown) waveguide mode is further observed on the low incident angle side.
図６に本実施の形態における、種々の波形の電界によるＥＯ信号の例を示す。下欄に信号線８ａ，８ｂ間の電界（Ｖ／μｍ）、上欄にＥＯ信号（ｍＶ）を示す。横軸は時間（ｍｓ）である。図６（ａ）に正弦波、図６（ｂ）に鋸波、図６（ｃ）に矩形波の電界信号の例を示す。いずれもＴＴＬレベル（０〜５Ｖ）の電界信号で、約０〜２０ｍＶのＥＯ信号が得られた。 FIG. 6 shows an example of an EO signal by various electric fields in this embodiment. The lower column shows the electric field (V / μm) between the signal lines 8a and 8b, and the upper column shows the EO signal (mV). The horizontal axis is time (ms). FIG. 6A shows an example of a sine wave, FIG. 6B shows an example of a sawtooth wave, and FIG. 6C shows an example of a rectangular wave electric field signal. In both cases, an EO signal of about 0 to 20 mV was obtained with an electric field signal of a TTL level (0 to 5 V).
図７は電界センサを基板７上で走査する様子を示す。ＥＳ１は電界センサで、金属薄膜２、ＥＯポリマー３はプリズム１の底面に形成されているが、図面では省略されている。９ａ、９ｂは基板７上に搭載された電極である。導波路モード光波が入射光と共鳴する条件において最も感度が高い入射角θ１で、ｐ−偏光の入射光を照射した際の反射光強度を位置に対して検出する。入射光すなわち電界センサを走査することにより、あるいは、電極すなわち被測定試料を走査することにより、１次元あるいは２次元的な電界の検出を行うことができる。走査方向は基板７表面に平行であり、その方向を図中矢印で示している。 FIG. 7 shows how the electric field sensor is scanned on the substrate 7. ES1 is an electric field sensor, and the metal thin film 2 and the EO polymer 3 are formed on the bottom surface of the prism 1, but are omitted in the drawing. Reference numerals 9 a and 9 b denote electrodes mounted on the substrate 7. The reflected light intensity is detected with respect to the position when the p-polarized incident light is irradiated at the incident angle θ1 having the highest sensitivity under the condition that the waveguide mode light wave resonates with the incident light. One-dimensional or two-dimensional electric field can be detected by scanning incident light, that is, an electric field sensor, or by scanning electrodes, that is, a sample to be measured. The scanning direction is parallel to the surface of the substrate 7, and the direction is indicated by an arrow in the figure.
図８に走査時の位置Ｘ（ｍｍ）とＥＯ信号のシフト量ΔＲ（ｍＶ）との関係を示す。この例では、入射光を走査した。電界センサＥＳ１が電極９ａ，９ｂの上にあるときは約０．７ｍＶの高レベルのＥＯ信号が得られ、電界センサＥＳ１が電極９ａ，９ｂ上にないときは約０．１ｍＶの低レベルのＥＯ信号が得られ、ＥＯ信号が電界の位置により変化していることがわかる。なお、第１の実施の形態においても、電界センサを基板上で走査可能である。 FIG. 8 shows the relationship between the position X (mm) during scanning and the shift amount ΔR (mV) of the EO signal. In this example, incident light was scanned. A high level EO signal of about 0.7 mV is obtained when the electric field sensor ES1 is on the electrodes 9a, 9b, and a low level EO signal of about 0.1 mV is obtained when the electric field sensor ES1 is not on the electrodes 9a, 9b. A signal is obtained, and it can be seen that the EO signal changes depending on the position of the electric field. In the first embodiment, the electric field sensor can be scanned on the substrate.
本実施の形態におけるセンシング方法の処理フロー例については、図４における第１の実施の形態における処理フロー例と同じである。
また、ここでは、導波路モード光波を用いて、反射波の強度の変化を検出する例について説明したが、位相の変化、共鳴波長の変化を検出することも可能である。
The processing flow example of the sensing method in the present embodiment is the same as the processing flow example in the first embodiment in FIG.
Although an example in which the change in the intensity of the reflected wave is detected using a waveguide mode light wave has been described here, it is also possible to detect a change in phase and a change in resonance wavelength.
〔第３の実施の形態〕
第３の実施の形態は、局在化表面プラズモンの共鳴状態の変化から電界を検出する例を説明する。
[Third Embodiment]
In the third embodiment, an example in which an electric field is detected from a change in the resonance state of localized surface plasmons will be described.
図９に局在化表面プラズモンを利用した電界センサの構成例を示す。図９（ａ）、（ｂ）で構成が異なる。図９（ａ）の電界センサＥＳ２は、光ファイバ１１（コア１２、クラッド１３）の端面に金（Ａｕ），銀（Ａｇ）等の金属ナノ微粒子１４を分散した電気光学効果を有する電気光学材料（以下、ＥＯ材料という）１５を塗布した構成であり、図９（ｂ）の電界センサＥＳ３は、光ファイバ１１（コア１２、クラッド１３）の端面に金Ａｕ，銀Ａｇ等の金属微粒子１４を堆積して、金属微粒子層１４ａを形成し、金属微粒子層１４ａ上にＥＯ材料１５を塗布した構成である。コア１２を通して入射光１６を金属ナノ微粒子１４に照射すると、金属ナノ微粒子１４表面に局在化表面プラズモンが励起される。金属ナノ微粒子１４への入射の際には、特に球状の場合には常に局在化表面プラズモンの共鳴が生じるので、反射光１７に変化が反映される。 FIG. 9 shows a configuration example of an electric field sensor using localized surface plasmons. 9A and 9B are different in configuration. The electric field sensor ES2 of FIG. 9A is an electro-optic material having an electro-optic effect in which metal nanoparticles 14 such as gold (Au) and silver (Ag) are dispersed on the end face of the optical fiber 11 (core 12 and clad 13). (Hereinafter referred to as EO material) 15 is applied, and the electric field sensor ES3 of FIG. 9B has metal fine particles 14 such as gold Au and silver Ag on the end face of the optical fiber 11 (core 12 and clad 13). In this configuration, the metal fine particle layer 14a is deposited, and the EO material 15 is applied onto the metal fine particle layer 14a. When incident light 16 is irradiated to the metal nanoparticles 14 through the core 12, localized surface plasmons are excited on the surface of the metal nanoparticles 14. When incident on the metal nanoparticle 14, especially in the case of a spherical shape, resonance of localized surface plasmon always occurs, so that a change is reflected in the reflected light 17.
金属ナノ微粒子１４表面に励起される局在化表面プラズモンの共鳴状態（反射光の強度、位相、共鳴波長に反映される）は周囲の材料の屈折率により変化するので、ＥＯポリマーのようなＥＯ材料を周囲に配置すれば、電界を検出可能である。局在化表面プラズモンを利用した電界センサＥＳ２，ＥＳ３は光ファイバ１１の先端に構成できるので、微小領域の電界や、隙間部分の電界を検出する場合等に便利である。 Since the resonance state of the localized surface plasmon excited on the surface of the metal nanoparticle 14 (reflected by the intensity, phase, and resonance wavelength of reflected light) changes depending on the refractive index of the surrounding material, EO such as EO polymer is used. If the material is placed around, the electric field can be detected. Since the electric field sensors ES2 and ES3 using localized surface plasmons can be configured at the tip of the optical fiber 11, it is convenient for detecting an electric field in a minute region or an electric field in a gap portion.
図１０に局在化表面プラズモンを利用した電界センサＥＳ２，ＥＳ３を用いる電界検出例を示す。図１０（ａ）は横電界を、図１０（ｂ）は縦電界を検出する例である。基板１８上に搭載した信号線１９ａ，１９ｂ間に電位差を設け、その電界中に電界センサＥＳ２又はＥＳ３の金属ナノ微粒子１４とＥＯ材料１５を含む先端部分を入れると、ＥＯ材料１５の屈折率が変化し、局在化表面プラズモンの共鳴状態が変化するので、電界を検出可能である。 FIG. 10 shows an example of electric field detection using electric field sensors ES2 and ES3 using localized surface plasmons. FIG. 10A shows an example of detecting a horizontal electric field, and FIG. 10B shows an example of detecting a vertical electric field. When a potential difference is provided between the signal lines 19a and 19b mounted on the substrate 18, and the tip portion including the metal nanoparticles 14 of the electric field sensor ES2 or ES3 and the EO material 15 is placed in the electric field, the refractive index of the EO material 15 is increased. Change, and the resonance state of the localized surface plasmon changes, so that the electric field can be detected.
図１１に本実施の形態におけるセンシング方法の処理フロー例を示す。図４における第１の実施の形態における処理フロー例において、工程Ｓ００２における表面プラズモン励起又は導波路モード光波励起が局在化表面プラズモン励起に代わり、電界センサの構成が異なる他は同様なので、説明を省略する。なお、第１の実施の形態における工程Ｓ００１〜Ｓ００７が本実施の形態におけるＳ１０１〜Ｓ１０７に対応する。 FIG. 11 shows a processing flow example of the sensing method in the present embodiment. In the example of the processing flow in the first embodiment in FIG. 4, the surface plasmon excitation or waveguide mode light wave excitation in step S002 is the same except that the configuration of the electric field sensor is different from the localized surface plasmon excitation. Omitted. Note that steps S001 to S007 in the first embodiment correspond to S101 to S107 in the present embodiment.
ここでは、局在化表面プラズモン共鳴について、反射波の強度の変化を検出する例について説明したが、位相の変化、共鳴波長の変化を検出することも可能である。また、金属ナノ微粒子に代えて、金属の粗い構造やグレーティングを形成しても、局在化表面プラズモン共鳴が生じるので、電界を検出することが可能である。 Here, an example of detecting a change in the intensity of a reflected wave has been described for localized surface plasmon resonance, but a change in phase and a change in resonance wavelength can also be detected. Further, even when a rough metal structure or a grating is formed instead of the metal nanoparticle, localized surface plasmon resonance occurs, so that an electric field can be detected.
〔第４の実施の形態〕
第４の実施の形態は、局在化表面プラズモンの共鳴状態の変化から電界を検出する別の例を説明する。
[Fourth Embodiment]
The fourth embodiment describes another example in which an electric field is detected from a change in the resonance state of localized surface plasmons.
第３の実施の形態では光ファイバ端面に金ナノ微粒子等とＥＯ材料を形成したが、本実施の形態では、透明な基板上に金ナノ微粒子等とＥＯ材料を形成するものである。すなわち、透明な基板上に金属の粗い構造やグレーティングなどを構築する、あるいは、金ナノ微粒子を固定しておく。これらの構成でも局在化表面プラズモン共鳴が発生する。そこへ、ＥＯポリマーなどＥＯ効果を示す材料を塗布等により形成する。この局在化表面プラズモン共鳴はＥＯ材料の屈折率に敏感であるため、電界の状態は共鳴状態の変化となって検出可能である。 In the third embodiment, the gold nanoparticles and the EO material are formed on the end face of the optical fiber. In this embodiment, the gold nanoparticles and the EO material are formed on a transparent substrate. That is, a rough metal structure or a grating is constructed on a transparent substrate, or gold nanoparticles are fixed. Even in these configurations, localized surface plasmon resonance occurs. A material exhibiting an EO effect such as an EO polymer is formed there by coating or the like. Since this localized surface plasmon resonance is sensitive to the refractive index of the EO material, the state of the electric field can be detected as a change in the resonance state.
本実施の形態におけるセンシング方法の処理フロー例については、図１１に示す第３の実施の形態における処理フロー例において、電界センサの構成が異なる他は同様なので、説明を省略する。 The processing flow example of the sensing method in the present embodiment is the same as the processing flow example in the third embodiment shown in FIG. 11 except that the configuration of the electric field sensor is different.
以上、本発明の実施の形態について説明したが、本発明は上記の実施の形態に限定されるものではなく、本発明の趣旨を逸脱しない範囲で実施の形態に種々変更を加えられることは明白である。例えば、以上の実施の形態では、金属層として金を、電気光学薄膜として高分子ポリマーを用いる例を説明したが、これに限定されない。合金でも表面プラズモンの励起を期待でき、電気光学薄膜として誘電体結晶薄膜を用いても良い。また、局在化表面プラズモンの共鳴状態の変化を用いる電界センサの場合には、反射光の変化の検出に限られず、透過光や散乱光の変化を検出しても良い。また、電界センサと、表面プラズモン、導波路モード光波又は局在化表面プラズモンを励起する光を発光する光源と、電界を検出する光検出器と、光検出器で検出された電界の状態を記憶し、表示する処理装置とを備えて電界センシング装置を構成してもよく、また、ＣＣＤカメラを使用して、反射スペクトルを一括処理してもよく、エリプソメトリと組み合わせて反射波の位相を測定し、感度を向上しても良い。
また、電気光学効果を有する材料に代えて、磁気光学効果を有する材料を利用すれば、電界の代わりに磁界を検出できる可能性がある。
Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and various modifications can be made to the embodiments without departing from the spirit of the present invention. It is. For example, in the above embodiment, the example in which gold is used as the metal layer and the high molecular polymer is used as the electro-optic thin film has been described. However, the present invention is not limited to this. An alloy can be expected to excite surface plasmons, and a dielectric crystal thin film may be used as the electro-optic thin film. Further, in the case of an electric field sensor that uses a change in the resonance state of localized surface plasmons, it is not limited to detecting a change in reflected light, but a change in transmitted light or scattered light may be detected. It also stores an electric field sensor, a light source that emits light that excites surface plasmons, waveguide mode light waves, or localized surface plasmons, a photodetector that detects the electric field, and the state of the electric field detected by the photodetector. In addition, the electric field sensing device may be configured with a processing device for display, or the reflection spectrum may be collectively processed using a CCD camera, and the phase of the reflected wave is measured in combination with ellipsometry. In addition, the sensitivity may be improved.
If a material having a magneto-optic effect is used instead of a material having an electro-optic effect, there is a possibility that a magnetic field can be detected instead of an electric field.
本発明は、非接触の電界検出に利用される。 The present invention is used for non-contact electric field detection.
１ プリズム
２ 金属薄膜
３ 電気光学薄膜
４ 入射光
５ 反射光
６ 光検出器
７ 基板
８ａ、８ｂ 信号線
９ａ、９ｂ 電極
１１ 光ファイバ
１２ コア
１３ クラッド
１４ 金属ナノ微粒子
１４ａ 金属微粒子層
１５ 電気光学材料
１６ 入射光
１７ 反射光
１８ 基板
１９ａ、１９ｂ 信号線
ＥＳ１〜ＥＳ３ 電界センサ
Ｘ 走査位置
θＲ 共鳴角
θ１、θ２ 導波路モード光波の入射角
DESCRIPTION OF SYMBOLS 1 Prism 2 Metal thin film 3 Electro-optic thin film 4 Incident light 5 Reflected light 6 Photo detector 7 Substrate 8a, 8b Signal line 9a, 9b Electrode 11 Optical fiber 12 Core 13 Cladding 14 Metal nanoparticle 14a Metal particle layer 15 Electrooptic material 16 Incident light 17 Reflected light 18 Substrate 19a, 19b Signal line
ES1-ES3 Electric field sensor X Scanning position θ R Resonance angles θ1, θ2 Incident angle of waveguide mode light wave
Claims (10)
電界センサ。 A metal layer is formed on the surface of the prism, an electro-optic thin film having an electro-optic effect is formed on the surface of the metal layer, and the total reflection attenuation method that is totally reflected on the surface of the prism is used. Detecting an electric field from a change in resonance state of surface plasmon excited on the surface of the metal layer due to a change in refractive index of the electro-optic thin film or a change in excitation state of a waveguide mode light wave excited in the electro-optic thin film;
Electric field sensor.
請求項１に記載の電界センサ。 A change in resonance state of the surface plasmon or a change in excitation state of the waveguide mode light wave is detected by a change in intensity, phase or resonance wavelength of reflected light in the total reflection attenuation method;
The electric field sensor according to claim 1.
電界センサ。 A metal fine particle layer or a metal grating layer having a size capable of exciting localized surface plasmons is formed on an optical fiber end face or a light transmissive substrate surface, and has an electro-optic effect on the surface of the metal fine particle layer or the metal grating layer. An electro-optic thin film is formed, and the localized surface plasmon caused by a change in the refractive index of the electro-optic thin film by applying an electric field using reflected light, transmitted light, or scattered light from the metal fine particle layer or the metal grating layer. Detecting an electric field from a change in resonance state;
Electric field sensor.
電界センサ。 An electro-optic thin film having an electro-optic effect is formed on the end face of the optical fiber or the surface of the light-transmitting substrate, in which metal fine particles having a size that can excite localized surface plasmons are dispersed. Detecting the electric field from the change in the resonance state of the localized surface plasmon due to the change in the refractive index of the electro-optic thin film by applying the electric field using the scattered light;
Electric field sensor.
請求項３又は請求項４に記載の電界センサ。 A change in the resonance state of the localized surface plasmon is detected by a change in the intensity, phase or resonance wavelength of the reflected, transmitted or scattered light;
The electric field sensor according to claim 3 or 4.
電界センシング装置。 6. The electric field sensor according to claim 1, a light source that emits light that excites the surface plasmon, the waveguide mode light wave, or the localized surface plasmon, and the electric field is detected. A photodetector and a processing device for storing and displaying a state of an electric field detected by the photodetector;
Electric field sensing device.
請求項６に記載の電界センシング装置。 The plane of the prism is movable in parallel;
The electric field sensing device according to claim 6.
前記電界センサの前記金属層内に表面プラズモンを又は前記電気光学薄膜内に導波路モード光波を励起して、全反射減衰法を用いて反射光を検出する工程と、
前記電界センサに電界を印加する工程と、
前記電界センサの前記金属層内に表面プラズモンを又は前記電気光学薄膜内に導波路モード光波を励起して、全反射減衰法を用いて反射光の変化を検出する工程と、
前記反射光の変化から電界を検出する工程とを備える；
電界センシング方法。 Preparing the electric field sensor according to claim 1;
Exciting a surface plasmon in the metal layer of the electric field sensor or a waveguide mode light wave in the electro-optic thin film to detect reflected light using a total reflection attenuation method;
Applying an electric field to the electric field sensor;
Exciting a surface plasmon in the metal layer of the electric field sensor or a waveguide mode light wave in the electro-optic thin film, and detecting a change in reflected light using a total reflection attenuation method;
Detecting an electric field from a change in the reflected light;
Electric field sensing method.
前記電界センサの前記金属微粒子層又は前記金属グレーティング層の表面に局在化表面プラズモンを励起して、前記金属微粒子層又は前記金属グレーティング層からの反射光、透過光又は散乱光を検出する工程と、
前記電界センサに電界を印加する工程と、
前記電界センサの前記金属微粒子層又は前記金属グレーティング層の表面に局在化表面プラズモンを励起して、前記金属微粒子層又は前記金属グレーティング層からの反射光、透過光又は散乱光の変化を検出する工程と、
前記反射光、透過光又は散乱光の変化から電界を検出する工程とを備える；
電界センシング方法。 Preparing an electric field sensor according to claim 3;
Exciting a localized surface plasmon on the surface of the metal fine particle layer or the metal grating layer of the electric field sensor to detect reflected light, transmitted light or scattered light from the metal fine particle layer or the metal grating layer; ,
Applying an electric field to the electric field sensor;
A localized surface plasmon is excited on the surface of the metal fine particle layer or the metal grating layer of the electric field sensor to detect a change in reflected light, transmitted light or scattered light from the metal fine particle layer or the metal grating layer. Process,
Detecting an electric field from a change in the reflected light, transmitted light or scattered light;
Electric field sensing method.
前記電界センサの前記金属微粒子の表面に局在化表面プラズモンを励起して、前記金属微粒子からの反射光、透過光又は散乱光を検出する工程と、
前記電界センサに電界を印加する工程と、
前記電界センサの前記金属微粒子の表面に局在化表面プラズモンを励起して、前記金属微粒子からの反射光、透過光又は散乱光の変化を検出する工程と、
前記反射光、透過光又は散乱光の変化から電界を検出する工程とを備える；
電界センシング方法。
Preparing an electric field sensor according to claim 4;
Exciting a localized surface plasmon on the surface of the metal fine particle of the electric field sensor to detect reflected light, transmitted light or scattered light from the metal fine particle;
Applying an electric field to the electric field sensor;
Exciting a localized surface plasmon on the surface of the metal fine particle of the electric field sensor to detect a change in reflected light, transmitted light or scattered light from the metal fine particle;
Detecting an electric field from a change in the reflected light, transmitted light or scattered light;
Electric field sensing method.
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