JP2014240957A - Plasmon waveguide element and manufacturing method thereof - Google Patents
Plasmon waveguide element and manufacturing method thereof Download PDFInfo
- Publication number
- JP2014240957A JP2014240957A JP2014099172A JP2014099172A JP2014240957A JP 2014240957 A JP2014240957 A JP 2014240957A JP 2014099172 A JP2014099172 A JP 2014099172A JP 2014099172 A JP2014099172 A JP 2014099172A JP 2014240957 A JP2014240957 A JP 2014240957A
- Authority
- JP
- Japan
- Prior art keywords
- metal
- metal walls
- pair
- walls
- light
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Landscapes
- Mechanical Light Control Or Optical Switches (AREA)
- Optical Integrated Circuits (AREA)
- Micromachines (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
Description
本発明は、プラズモン導波路素子、およびその作製方法に関する。さらに詳しくは、金属中の自由電子の集団的振動であるプラズモンを利用した光導波路を有するプラズモン導波路素子、およびその作製方法に関する。 The present invention relates to a plasmon waveguide element and a manufacturing method thereof. More specifically, the present invention relates to a plasmon waveguide element having an optical waveguide using plasmons that are collective vibrations of free electrons in a metal, and a method for manufacturing the plasmon waveguide element.
情報の大容量化に伴って光学システムの集積化が進み、ナノスケールの光デバイスの開発が進められている。従来、光の回折限界によりその空間分解能は光の波長程度に制限されるため、ナノスケールの光デバイスの実現は困難とされていた。しかし、近年、ナノオーダーの金属微細構造物に生じる伝搬型表面プラズモンを利用することにより、光の回折限界以下の領域で光の伝搬を可能にしたプラズモン導波路が提案されている。 With the increase in information capacity, integration of optical systems has progressed, and nanoscale optical devices have been developed. Conventionally, since the spatial resolution is limited to the wavelength of light due to the diffraction limit of light, it has been difficult to realize a nanoscale optical device. However, in recent years, a plasmon waveguide has been proposed in which propagation of surface plasmons generated in a nano-order metal microstructure can be used to transmit light in a region below the light diffraction limit.
特許文献１には、光が入射する入射側プラズモン導波路と、光が出射する出射側プラズモン導波路と、入射側プラズモン導波路と出射側プラズモン導波路とを結ぶ接続部と、接続部から入射側プラズモン導波路または出射側プラズモン導波路と交差する方向に延出し、光が反射する終端部を有するプラズモン干渉構造とを備えるプラズモン導波路が開示されている。プラズモン干渉構造を所定の大きさや形状に形成することにより、出射側プラズモン導波路から出射する光の透過率および強度を所望のものとすることができる。 In Patent Document 1, an incident-side plasmon waveguide into which light is incident, an exit-side plasmon waveguide from which light is emitted, a connecting portion connecting the incident-side plasmon waveguide and the emitting-side plasmon waveguide, and incident from the connecting portion A plasmon waveguide is disclosed that includes a plasmon interference structure that extends in a direction crossing the side plasmon waveguide or the emission side plasmon waveguide and has a terminal portion that reflects light. By forming the plasmon interference structure in a predetermined size and shape, the transmittance and intensity of light emitted from the emission-side plasmon waveguide can be made desired.
しかし、特許文献１に記載のプラズモン導波路をはじめ、従来のプラズモン導波路素子はその金属微細構造が固定されており、１つの素子は特定のプラズモン共鳴波長しか有しないものであった。すなわち、１つの素子が伝搬する光の波長は固定されていた。また、光の伝搬距離はプラズモン導波路の形状や構造に依存することから、従来のプラズモン導波路素子は光の伝搬距離が固定されていた。そのため、プラズモン導波路を伝搬させる光の波長や伝搬距離を変更するためには、素子を交換する必要があった。 However, the metal fine structure of the conventional plasmon waveguide element including the plasmon waveguide described in Patent Document 1 is fixed, and one element has only a specific plasmon resonance wavelength. That is, the wavelength of light propagating through one element is fixed. In addition, since the light propagation distance depends on the shape and structure of the plasmon waveguide, the light propagation distance is fixed in the conventional plasmon waveguide element. Therefore, in order to change the wavelength or propagation distance of light propagating through the plasmon waveguide, it is necessary to replace the element.
なお、非特許文献１には以下の記載がある。金属膜のギャップを伝搬するギャッププラズモンが存在する。ギャップの四隅に電界が集中し、対向する隅の電磁界同士が結合して伝搬する基本モードギャッププラズモンとギャップの中を通常の導波モードのように伝搬する第二モードギャッププラズモンが存在する。計算によると、第二モードギャッププラズモンは取り扱いが容易であり、簡単に励起できることから、プラズモン導波路として有望である。また、導波路は表面プラズモンを広範囲で使う際に不可欠なデバイスである。
非特許文献２には、ストライプ型や細線型、溝型、楔型、ギャップ型、配列金微粒子型など多くの型の導波路が開発されていることが記載されている。金属材料としては、なるべく光損失の小さいものが有利であり、銀の研究が多いが、安定性の高い金の導波路研究も活発である。
Non-Patent Document 1 has the following description. There are gap plasmons that propagate through the gap of the metal film. There are fundamental mode gap plasmons in which electric fields are concentrated at the four corners of the gap and electromagnetic fields in opposite corners are coupled and propagated, and there are second mode gap plasmons that propagate in the gap like normal waveguide modes. According to the calculation, the second mode gap plasmon is promising as a plasmon waveguide because it is easy to handle and can be easily excited. A waveguide is an indispensable device when using surface plasmons in a wide range.
Non-Patent Document 2 describes that many types of waveguides such as a stripe type, a fine wire type, a groove type, a wedge type, a gap type, and an arrayed gold fine particle type have been developed. As a metal material, a material with as little light loss as possible is advantageous, and silver has a lot of research, but research on a highly stable gold waveguide is also active.
本発明は上記事情に鑑み、１つの素子で伝搬させる光の波長および伝搬距離を変更できるプラズモン導波路素子、およびその作製方法を提供することを目的とする。 In view of the above circumstances, an object of the present invention is to provide a plasmon waveguide element that can change the wavelength and propagation distance of light propagated by one element, and a method for manufacturing the plasmon waveguide element.
第１発明のプラズモン導波路素子は、所定間隔を開けて対向するように配置された一対の金属壁からなる導波路と、前記金属壁同士を接近または離間させるアクチュエータと、を備えることを特徴とする。
第２発明のプラズモン導波路素子は、第１発明において、前記アクチュエータは、前記一対の金属壁にそれぞれ逆符号または同符号の電荷を帯電させ、該金属壁の間に働く静電引力または静電斥力により、該金属壁同士を接近または離間させるものであることを特徴とする。
第３発明のプラズモン導波路素子は、第２発明において、前記アクチュエータは、一対の電極を備えており、前記一対の金属壁の一方は、前記一対の電極の一方に接続されており、前記一対の金属壁の他方は、前記一対の電極の他方に接続されていることを特徴とする。
第４発明のプラズモン導波路素子は、第３発明において、前記電極と、該電極に接続された前記金属壁とは、所定間隔を開けて対向するように配置されていることを特徴とする。
第５発明のプラズモン導波路素子は、第１、第２、第３または第４発明において、前記一対の金属壁は、光の入射側または出射側の一方の端部が固定されており、他方の端部が可動となっていることを特徴とする。
第６発明のプラズモン導波路素子の作製方法は、基板上に金属薄膜を成膜してチップを得る工程と、前記チップの基板側からエッチングして、導波路を構成する一対の金属壁の間の金属薄膜および基板を除去する工程と、前記チップの金属薄膜側からエッチングして、金属壁と電極との間の金属薄膜を、接続部を残すように除去する工程と、を備えることを特徴とする。
A plasmon waveguide element according to a first aspect of the present invention includes a waveguide composed of a pair of metal walls arranged so as to face each other with a predetermined gap therebetween, and an actuator that approaches or separates the metal walls. To do.
The plasmon waveguide element according to a second aspect is the plasmon waveguide element according to the first aspect, wherein the actuator charges the pair of metal walls with electric charges of opposite signs or the same sign, and acts between the metal walls. The metal walls are made to approach or separate from each other by repulsion.
In a plasmon waveguide element according to a third aspect of the present invention, in the second aspect, the actuator includes a pair of electrodes, and one of the pair of metal walls is connected to one of the pair of electrodes. The other of the metal walls is connected to the other of the pair of electrodes.
A plasmon waveguide element according to a fourth invention is characterized in that, in the third invention, the electrode and the metal wall connected to the electrode are arranged to face each other with a predetermined gap.
The plasmon waveguide element according to a fifth aspect of the present invention is the first, second, third or fourth aspect of the present invention, wherein the pair of metal walls have one end on the light incident side or the light emission side fixed to the other. It is characterized in that the end of the is movable.
According to a sixth aspect of the present invention, there is provided a method for producing a plasmon waveguide element comprising: a step of forming a metal thin film on a substrate to obtain a chip; and a step of etching from the substrate side of the chip between a pair of metal walls constituting the waveguide. Removing the metal thin film and the substrate, and etching from the metal thin film side of the chip to remove the metal thin film between the metal wall and the electrode so as to leave a connection portion. And
第１発明によれば、アクチュエータにより金属壁同士を接近または離間させるので、金属壁同士の間隔を変化させて導波路のプラズモン共鳴波長を変更でき、１つの素子で伝搬させる光の波長を変更できる。また、導波路の構造を変更でき、１つの素子で伝搬させる光の伝搬距離を変更できる。
第２発明によれば、金属壁の間に働く静電引力または静電斥力により、金属壁同士を接近または離間させるので、アクチュエータを簡易な構造とすることができる。
第３発明によれば、一対の電極間に電圧を印加すれば、一対の金属壁にそれぞれ逆符号または同符号の電荷を帯電させることができるので、金属壁の間に働く静電引力または静電斥力により、金属壁同士を接近または離間させることができる。
第４発明によれば、電極に電圧を印加すれば、電極と金属壁とにそれぞれ同符号の電荷を帯電させることができるので、電極と金属壁との間に働く静電斥力により、金属壁を電極から離間させ、金属壁同士を接近させることができる。
第５発明によれば、一対の金属壁は、光の入射側または出射側の一方の端部同士の間隔が変化せず、他方の端部同士の間隔が変化する。そのため、導波路を光の伝搬方向に先細りに変形でき、光を集光することで導波路の出射側端部の局所的な電場強度を入射光よりも増強できる。
第６発明によれば、金属壁の間のエッチングを基板側から行うことで、金属薄膜側からのエッチングが１回で済み、金属壁をなめらかな形状に形成することができる。
According to the first aspect of the invention, the metal walls are moved closer to or away from each other by the actuator, so that the plasmon resonance wavelength of the waveguide can be changed by changing the interval between the metal walls, and the wavelength of light propagated by one element can be changed. . Further, the structure of the waveguide can be changed, and the propagation distance of light propagated by one element can be changed.
According to the second aspect of the invention, the metal walls are brought closer to or separated from each other by the electrostatic attractive force or electrostatic repulsive force acting between the metal walls, so that the actuator can have a simple structure.
According to the third aspect of the invention, if a voltage is applied between the pair of electrodes, the pair of metal walls can be charged with the opposite sign or the same sign, respectively. The metal walls can be moved closer to or away from each other by the electric force.
According to the fourth aspect of the present invention, if a voltage is applied to the electrode, the electrode and the metal wall can be charged with the same sign, so the electrostatic repulsive force acting between the electrode and the metal wall causes the metal wall to be charged. Can be separated from the electrodes and the metal walls can be brought close to each other.
According to the fifth aspect of the present invention, in the pair of metal walls, the interval between the one end portions on the light incident side or the emission side does not change, and the interval between the other end portions changes. Therefore, the waveguide can be deformed in a tapered manner in the light propagation direction, and by condensing the light, the local electric field strength at the output side end of the waveguide can be enhanced compared to the incident light.
According to the sixth aspect of the invention, by performing the etching between the metal walls from the substrate side, the etching from the metal thin film side is only required once, and the metal wall can be formed into a smooth shape.
つぎに、本発明の実施形態を図面に基づき説明する。
（第１実施形態）
本発明の第１実施形態に係るプラズモン導波路素子１は、厚さ100nm〜1mmの基板Ｂ上に、厚さ数百nm〜数十μmの金属薄膜Ｍを成膜したチップを、集束イオンビームなどにより図１および図２に示す構造に形成した、いわゆるNEMS（Nano Electro Mechanical System）である。ここで、基板Ｂとしては、絶縁体であり透光性を有する素材、例えば石英ガラス（SiO2）、窒化珪素（Si3N4）、炭化珪素（SiC）、酸化アルミニウム（Al2O3）などが用いられる。金属薄膜Ｍとしては、金、銀、アルミニウム、白金、銅、ナトリウム、酸化インジウムスズなどが用いられる。
Next, an embodiment of the present invention will be described with reference to the drawings.
(First embodiment)
The plasmon waveguide device 1 according to the first embodiment of the present invention is a focused ion beam in which a chip in which a metal thin film M having a thickness of several hundred nm to several tens of μm is formed on a substrate B having a thickness of 100 nm to 1 mm. This is a so-called NEMS (Nano Electro Mechanical System) formed in the structure shown in FIGS. Here, as the substrate B, a transparent material such as quartz glass (SiO 2 ), silicon nitride (Si 3 N 4 ), silicon carbide (SiC), aluminum oxide (Al 2 O 3 ) is used. Etc. are used. As the metal thin film M, gold, silver, aluminum, platinum, copper, sodium, indium tin oxide, or the like is used.
図１および図２に示すように、プラズモン導波路素子１は、所定間隔を開けて平行に対向するように配置された一対の金属壁１１、１２からなる導波路１０と、一対の電極２１、２２と、一方の金属壁１１と一方の電極２１とを電気的に接続する接続部２３と、他方の金属壁１２と他方の電極２２とを電気的に接続する接続部２４とから構成されている。なお、金属壁１１、１２、電極２１、２２、および接続部２３、２４が特許請求の範囲に記載のアクチュエータに相当する。 As shown in FIGS. 1 and 2, the plasmon waveguide element 1 includes a waveguide 10 composed of a pair of metal walls 11 and 12 arranged so as to face each other at a predetermined interval, and a pair of electrodes 21, 22, a connection portion 23 that electrically connects one metal wall 11 and one electrode 21, and a connection portion 24 that electrically connects the other metal wall 12 and the other electrode 22. Yes. The metal walls 11 and 12, the electrodes 21 and 22, and the connection portions 23 and 24 correspond to the actuators described in the claims.
金属壁１１、１２は、金属薄膜Ｍで基板Ｂに立設する壁状に形成された微細金属壁である。金属壁１１、１２の厚さ（図２における左右方向の寸法）は数百nmであり、後述のごとく金属壁１１、１２は撓むことができる。金属壁１１、１２の高さ寸法（図２における上下方向の寸法）は金属薄膜Ｍの厚さと同じ数百nm〜数十μmであり、長さ寸法（図２における紙面に対して垂直な方向の寸法）は数百nm〜数十μmである。また、金属壁１１と金属壁１２との間は金属薄膜Ｍが削られており絶縁されている。なお、金属壁１１と金属壁１２との間の金属薄膜Ｍに加えて、その下部の基板Ｂを削ってもよい。金属壁１１、１２同士の間隔は数百nmであり、光の波長程度またはそれ以下（以下、サブ波長という。）である。金属壁１１と金属壁１２との間の空間が、光を伝搬する導波路１０となっている。 The metal walls 11 and 12 are fine metal walls formed in a wall shape standing on the substrate B with the metal thin film M. The thickness of the metal walls 11 and 12 (dimension in the left-right direction in FIG. 2) is several hundred nm, and the metal walls 11 and 12 can be bent as will be described later. The height dimension (the vertical dimension in FIG. 2) of the metal walls 11 and 12 is several hundred nm to several tens of μm, which is the same as the thickness of the metal thin film M, and the length dimension (direction perpendicular to the paper surface in FIG. 2). ) Is several hundred nm to several tens of μm. Further, the metal thin film M is cut and insulated between the metal wall 11 and the metal wall 12. In addition to the metal thin film M between the metal wall 11 and the metal wall 12, the lower substrate B may be shaved. The interval between the metal walls 11 and 12 is several hundred nm, which is about the wavelength of light or less (hereinafter referred to as sub-wavelength). A space between the metal wall 11 and the metal wall 12 is a waveguide 10 that propagates light.
電極２１、２２は、金属壁１１、１２を挟んで対向した位置に配置されており、それぞれ数十μm〜数百μm四方の矩形である。もちろん、電極２１と電極２２との間は金属薄膜Ｍが削られており絶縁されている。この電極２１、２２には、図示しない電源が接続され、電極２１、２２間に電圧を印加できるようになっている。 The electrodes 21 and 22 are arranged at positions facing each other with the metal walls 11 and 12 in between, and each has a rectangular shape of several tens μm to several hundreds μm square. Of course, the metal thin film M is shaved and insulated between the electrode 21 and the electrode 22. A power source (not shown) is connected to the electrodes 21 and 22 so that a voltage can be applied between the electrodes 21 and 22.
電極２１の金属壁１１側の側壁と金属壁１１とは所定間隔を開けて平行に対向するように配置されており、電極２２の金属壁１２側の側壁と金属壁１２とは所定間隔を開けて平行に対向するように配置されている。電極２１と金属壁１１との間には接続部２３が設けられており、電極２２と金属壁１２との間には接続部２４が設けられている。 The side wall of the electrode 21 on the metal wall 11 side and the metal wall 11 are arranged to face each other in parallel with a predetermined distance, and the side wall of the electrode 22 on the metal wall 12 side and the metal wall 12 are spaced with a predetermined distance. Are arranged to face each other in parallel. A connecting portion 23 is provided between the electrode 21 and the metal wall 11, and a connecting portion 24 is provided between the electrode 22 and the metal wall 12.
接続部２３、２４の厚さ（図２における上下方向の寸法）は、電極２１、２２の厚さ、および金属壁１１、１２の高さ寸法よりも薄く形成されている。また、接続部２３、２４の幅寸法（図２における左右方向の寸法）は数百nm〜数μmである。すなわち、電極２１と金属壁１１との間隔、および電極２２と金属壁１２との間隔はそれぞれ数百nm〜数μmである。 The thickness of the connecting portions 23 and 24 (the vertical dimension in FIG. 2) is formed thinner than the thickness of the electrodes 21 and 22 and the height of the metal walls 11 and 12. Moreover, the width dimension (the dimension of the left-right direction in FIG. 2) of the connection parts 23 and 24 is several hundred nm-several micrometers. That is, the distance between the electrode 21 and the metal wall 11 and the distance between the electrode 22 and the metal wall 12 are several hundred nm to several μm, respectively.
金属壁１１、１２は、下端部（基板Ｂ側の端部）が基板Ｂに固定されており接続部２３、２４とも固定されている。一方、金属壁１１、１２の上端部（金属薄膜Ｍ側の端部）は、金属壁１１、１２自体が撓むことで可動となっている。 The metal walls 11 and 12 are fixed to the substrate B at the lower ends (ends on the substrate B side) and are also fixed to the connection portions 23 and 24. On the other hand, the upper end portions (end portions on the metal thin film M side) of the metal walls 11 and 12 are movable by bending the metal walls 11 and 12 themselves.
以上のような構成のプラズモン導波路素子１は以下の手順で作製できる。
まず、基板Ｂ上に金属薄膜Ｍを成膜してチップを得る。つぎに、集束イオンビームなどを用いて、金属壁１１と金属壁１２との間の金属薄膜Ｍをエッチングにより除去するとともに、金属壁１１と電極２１との間、および金属壁１２と電極２２との間の金属薄膜Ｍを、接続部２３、２４を残すようにエッチングにより除去する。
The plasmon waveguide device 1 having the above configuration can be manufactured by the following procedure.
First, a metal thin film M is formed on the substrate B to obtain a chip. Next, the metal thin film M between the metal wall 11 and the metal wall 12 is removed by etching using a focused ion beam or the like, and between the metal wall 11 and the electrode 21 and between the metal wall 12 and the electrode 22. The metal thin film M between them is removed by etching so that the connecting portions 23 and 24 remain.
また、以下の手順で作製してもよい。
まず、基板Ｂ上に金属薄膜Ｍを成膜してチップを得る。つぎに、集束イオンビームなどを用いて、チップの基板側からエッチングして、金属壁１１と金属壁１２との間の金属薄膜Ｍおよび基板Ｂを除去する。つぎに、チップの金属薄膜側からエッチングして、金属壁１１と電極２１との間、および金属壁１２と電極２２との間の金属薄膜Ｍを、接続部２３、２４を残すように除去する。このような手順とすれば、金属壁１１、１２の間のエッチングを基板側から行うことで、金属薄膜側からのエッチングが１回で済み、金属壁１１、１２をなめらかな形状に形成することができる。
Moreover, you may produce in the following procedures.
First, a metal thin film M is formed on the substrate B to obtain a chip. Next, the metal thin film M and the substrate B between the metal wall 11 and the metal wall 12 are removed by etching from the substrate side of the chip using a focused ion beam or the like. Next, etching is performed from the metal thin film side of the chip to remove the metal thin film M between the metal wall 11 and the electrode 21 and between the metal wall 12 and the electrode 22 so as to leave the connection portions 23 and 24. . According to such a procedure, the etching between the metal walls 11 and 12 is performed from the substrate side, so that the etching from the metal thin film side is performed once, and the metal walls 11 and 12 are formed into a smooth shape. Can do.
図２に示すように、導波路１０には、プラズモン導波路素子１の裏面側（基板Ｂ側）から光Ｌｉが入射され、プラズモン導波路素子１の表面側（金属薄膜Ｍ側）から光Ｌｏが出射する。逆に、プラズモン導波路素子１の表面側（金属薄膜Ｍ側）から光が入射され、プラズモン導波路素子１の裏面側（基板Ｂ側）から光が出射するようにしてもよい。すなわち、本実施形態のプラズモン導波路素子１の導波路１０は、光の伝搬方向が基板Ｂに対して垂直方向である。 As shown in FIG. 2, light Li is incident on the waveguide 10 from the back surface side (substrate B side) of the plasmon waveguide element 1, and light Lo is transmitted from the surface side of the plasmon waveguide element 1 (metal thin film M side). Is emitted. Conversely, light may be incident from the front surface side (metal thin film M side) of the plasmon waveguide element 1 and light may be emitted from the rear surface side (substrate B side) of the plasmon waveguide element 1. That is, in the waveguide 10 of the plasmon waveguide element 1 of the present embodiment, the light propagation direction is perpendicular to the substrate B.
図３（ａ）に示すように、各電極２１、２２を逆符号（電極２１を正極、電極２２を負極）として、電極２１、２２間に電圧を印加すると、正極２１に接続された金属壁１１には正電荷が帯電し、負極２２に接続された金属壁１２には負電荷が帯電する。そうすると、一対の金属壁１１、１２にそれぞれ逆符号の電荷を帯電させることができ、金属壁１１、１２の間に働く静電引力により金属壁１１、１２が撓み、金属壁１１、１２同士を接近させることができる。 As shown in FIG. 3A, when the electrodes 21 and 22 are reversed (the electrode 21 is a positive electrode and the electrode 22 is a negative electrode) and a voltage is applied between the electrodes 21 and 22, a metal wall connected to the positive electrode 21 11 is charged with a positive charge, and the metal wall 12 connected to the negative electrode 22 is charged with a negative charge. Then, the pair of metal walls 11 and 12 can be charged with oppositely charged charges, and the metal walls 11 and 12 are bent by the electrostatic attractive force acting between the metal walls 11 and 12, so that the metal walls 11 and 12 are Can be approached.
また、電極２１と金属壁１１には正電荷が帯電し、電極２２と金属壁１２には負電荷が帯電する。そうすると、電極２１と金属壁１１、および電極２２と金属壁１２にそれぞれ同符号の電荷を帯電させることができ、電極２１、２２と金属壁１１、１２との間に働く静電斥力によっても金属壁１１、１２が撓み、金属壁１１、１２を電極２１、２２から離間させ、金属壁１１、１２同士を接近させることができる。電極２１、２２と金属壁１１、１２との間隔を狭くすれば、それらの間に働く静電斥力が強くなり、より低い印加電圧で金属壁１１、１２同士を接近させることができる。 Further, the electrode 21 and the metal wall 11 are positively charged, and the electrode 22 and the metal wall 12 are negatively charged. Then, the electrode 21 and the metal wall 11 and the electrode 22 and the metal wall 12 can be charged with the same sign, respectively, and the metal is also affected by the electrostatic repulsive force acting between the electrodes 21 and 22 and the metal walls 11 and 12. The walls 11 and 12 are bent, the metal walls 11 and 12 can be separated from the electrodes 21 and 22, and the metal walls 11 and 12 can be brought close to each other. If the space | interval of the electrodes 21 and 22 and the metal walls 11 and 12 is narrowed, the electrostatic repulsive force which acts between them will become strong, and the metal walls 11 and 12 can be made to approach each other with a lower applied voltage.
一方、図３（ｂ）に示すように、各電極２１、２２を同符号（電極２１および電極２２を正極または負極）として電圧を印加すると、一対の金属壁１１、１２にそれぞれ同符号の電荷を帯電させることができる。そうすると、金属壁１１、１２の間に働く静電斥力により金属壁１１、１２が撓み、金属壁１１、１２同士を離間させることができる。 On the other hand, as shown in FIG. 3B, when a voltage is applied with the electrodes 21 and 22 having the same sign (the electrodes 21 and 22 are positive or negative), the pair of metal walls 11 and 12 are charged with the same sign. Can be charged. If it does so, the metal walls 11 and 12 will bend by the electrostatic repulsive force which acts between the metal walls 11 and 12, and the metal walls 11 and 12 can be spaced apart.
なお、電極２１、２２と金属壁１１、１２との間には静電斥力が働くため、金属壁１１、１２同士を接近させる力も働く。しかし、金属壁１１、１２同士の間隔に比べて電極２１、２２と金属壁１１、１２との間隔を広くするなどして、金属壁１１、１２の間に働く静電斥力に比べて電極２１、２２と金属壁１１、１２との間に働く静電斥力を弱くすることで、金属壁１１、１２同士を離間させることができる。 In addition, since an electrostatic repulsive force acts between the electrodes 21 and 22 and the metal walls 11 and 12, the force which brings the metal walls 11 and 12 closer also acts. However, compared to the electrostatic repulsive force acting between the metal walls 11 and 12, for example, the distance between the electrodes 21 and 22 and the metal walls 11 and 12 is increased compared to the distance between the metal walls 11 and 12. , 22 and the metal walls 11, 12 can be weakened by separating the electrostatic repulsive force between the metal walls 11, 12.
金属壁１１、１２は弾性を有するので、金属壁１１、１２の間に働く静電引力や静電斥力、および電極２１、２２と金属壁１１、１２との間に働く静電斥力の大きさを変化させることで金属壁１１、１２同士の間隔を調整できる。すなわち、印加する電圧を調整することにより、金属壁１１、１２同士の間隔を調整できる。そして、印加電圧を０にすれば、金属壁１１、１２同士の間隔を元に戻すことができる。 Since the metal walls 11 and 12 have elasticity, the magnitude of the electrostatic attractive force and electrostatic repulsive force acting between the metal walls 11 and 12 and the electrostatic repulsive force acting between the electrodes 21 and 22 and the metal walls 11 and 12 are large. The distance between the metal walls 11 and 12 can be adjusted by changing. That is, the interval between the metal walls 11 and 12 can be adjusted by adjusting the voltage to be applied. If the applied voltage is set to 0, the interval between the metal walls 11 and 12 can be restored.
以上のように、プラズモン導波路素子１は、金属壁１１、１２同士の間隔を自在に変化させて導波路１０の構造を変化させることができるので、導波路１０のプラズモン共鳴波長を変更でき、１つの素子で伝搬させる光の波長を自在に変更できる。また、金属壁１１、１２同士の間隔と導波路１０のプラズモン共鳴波長が変化することにより、導波路１０を構成する金属への光の吸収量が変化するので、１つの素子で光の伝搬距離を自在に変更できる。 As described above, since the plasmon waveguide element 1 can change the structure of the waveguide 10 by freely changing the interval between the metal walls 11 and 12, the plasmon resonance wavelength of the waveguide 10 can be changed. The wavelength of light propagated by one element can be freely changed. In addition, since the amount of light absorbed by the metal constituting the waveguide 10 changes as the distance between the metal walls 11 and 12 and the plasmon resonance wavelength of the waveguide 10 change, the propagation distance of light by one element. Can be changed freely.
金属壁１１、１２は下端部が固定されており上端部が可動となっている。そのため、一対の金属壁１１、１２は、下端部同士の間隔が変化せず、上端部同士の間隔が変化する。 The metal walls 11 and 12 have a lower end fixed and an upper end movable. Therefore, as for a pair of metal walls 11 and 12, the space | interval of lower end parts does not change, but the space | interval of upper end parts changes.
図３（ａ）に示すように、各電極２１、２２を逆符号として電極２１、２２間に電圧を印加すると、一対の金属壁１１、１２は、下端部同士の間隔が変化せず、上端部同士が接近する。この場合、プラズモン導波路素子１の裏面側（基板Ｂ側）から光を入射すると、一対の金属壁１１、１２は、光の入射側端部（下端部）同士の間隔が変化せず、出射側端部（上端部）同士が接近しているので、導波路１０が光の伝搬方向に先細りとなる。そうすると、入射された光が集光されるので、導波路１０の出射側端部の局所的な電場強度を入射光よりも増強できる。 As shown in FIG. 3A, when a voltage is applied between the electrodes 21 and 22 with the electrodes 21 and 22 being reversed, the pair of metal walls 11 and 12 does not change the distance between the lower ends, and the upper ends The parts approach each other. In this case, when light is incident from the back surface side (substrate B side) of the plasmon waveguide element 1, the distance between the light incident side end portions (lower end portions) of the pair of metal walls 11 and 12 is not changed. Since the side end portions (upper end portions) are close to each other, the waveguide 10 is tapered in the light propagation direction. Then, since the incident light is collected, the local electric field strength at the output side end of the waveguide 10 can be enhanced more than the incident light.
図３（ｂ）に示すように、各電極２１、２２を同符号として電圧を印加すると、一対の金属壁１１、１２は、下端部同士の間隔が変化せず、上端部同士が離間する。この場合、プラズモン導波路素子１の表面側（金属薄膜Ｍ側）から光を入射すると、一対の金属壁１１、１２は、光の出射側端部（下端部）同士の間隔が変化せず、入射側端部（上端部）同士が離間しているので、導波路１０が光の伝搬方向に先細りとなる。そうすると、入射された光が集光されるので、導波路１０の出射側端部の局所的な電場強度を入射光よりも増強できる。 As shown in FIG. 3B, when a voltage is applied with the electrodes 21 and 22 having the same sign, the pair of metal walls 11 and 12 do not change the distance between the lower ends, and the upper ends are separated from each other. In this case, when light is incident from the surface side (metal thin film M side) of the plasmon waveguide element 1, the distance between the light emission side end portions (lower end portions) of the pair of metal walls 11 and 12 does not change. Since the incident-side end portions (upper end portions) are separated from each other, the waveguide 10 is tapered in the light propagation direction. Then, since the incident light is collected, the local electric field strength at the output side end of the waveguide 10 can be enhanced more than the incident light.
以上のように、一対の金属壁１１、１２は、光の入射側または出射側の一方の端部が固定されており、他方の端部が可動となっているので、導波路１０を光の伝搬方向に先細りに変形でき、光を集光することで導波路１０の出射側端部の局所的な電場強度を入射光よりも増強できる。 As described above, one end of the light incident side or the light exit side of the pair of metal walls 11 and 12 is fixed and the other end is movable. The local electric field intensity at the output side end of the waveguide 10 can be increased more than that of the incident light by condensing the light so as to be tapered in the propagation direction.
プラズモン導波路素子１は、金属壁１１、１２の間に働く静電引力または静電斥力により、金属壁１１、１２同士を接近または離間させるので、アクチュエータを簡易な構造とすることができる。
しかも、アクチュエータを含めたチップ全体をNEMSとして形成しているので、スケーリングメリットを活かした低電圧駆動や高速応答、高いフィルファクタが実現可能である。
Since the plasmon waveguide element 1 brings the metal walls 11 and 12 closer to or away from each other by electrostatic attraction or electrostatic repulsion acting between the metal walls 11 and 12, the actuator can have a simple structure.
Moreover, since the entire chip including the actuator is formed as a NEMS, low voltage driving, high-speed response and high fill factor can be realized by taking advantage of scaling.
（第２実施形態）
上記第１実施形態に係るプラズモン導波路素子１は、導波路１０の光の伝搬方向が基板Ｂに対して垂直方向であるが、これを基板Ｂに対して水平方向となる構造としてもよい。
図４および図５に示すように、本発明の第２実施形態に係るプラズモン導波路素子２は、所定間隔を開けて平行に対向するように配置された一対の金属壁１１、１２からなる導波路１０と、一対の電極２１、２２と、一方の金属壁１１と一方の電極２１とを接続する接続部２３と、他方の金属壁１２と他方の電極２２とを接続する接続部２４とから構成されている。金属壁１１、１２は、その周囲の金属薄膜Ｍおよび基板Ｂが除去されており、接続部２３、２４で電極２１、２２と接続されることにより、片持ち状態で空中に支持されている。
(Second Embodiment)
In the plasmon waveguide element 1 according to the first embodiment, the light propagation direction of the waveguide 10 is perpendicular to the substrate B. However, the plasmon waveguide element 1 may be configured to be horizontal to the substrate B.
As shown in FIGS. 4 and 5, the plasmon waveguide device 2 according to the second embodiment of the present invention is a conductive material composed of a pair of metal walls 11 and 12 arranged to face each other at a predetermined interval in parallel. From the waveguide 10, the pair of electrodes 21, 22, the connection part 23 that connects the one metal wall 11 and the one electrode 21, and the connection part 24 that connects the other metal wall 12 and the other electrode 22. It is configured. The metal walls 11 and 12 have the metal thin film M and the substrate B around them removed, and are connected to the electrodes 21 and 22 at the connection portions 23 and 24, so that they are supported in the air in a cantilever state.
図４に示すように、導波路１０には、プラズモン導波路素子１の一方の側面（図４における下側の側面）から光Ｌｉが入射され、プラズモン導波路素子１の他方の側面図４における上側の側面）から光Ｌｏが出射する。すなわち、本実施形態のプラズモン導波路素子２の導波路１０は、光の伝搬方向が基板Ｂに対して水平方向である。なお、本実施形態のプラズモン導波路素子２を、導波路１０の光の伝搬方向を基板Ｂに対して垂直方向となるように用いてもよい。 As shown in FIG. 4, light Li is incident on the waveguide 10 from one side surface (the lower side surface in FIG. 4) of the plasmon waveguide element 1, and the other side view of the plasmon waveguide element 1 in FIG. 4. Light Lo is emitted from the upper side surface. That is, in the waveguide 10 of the plasmon waveguide element 2 of the present embodiment, the light propagation direction is horizontal with respect to the substrate B. Note that the plasmon waveguide element 2 of the present embodiment may be used so that the light propagation direction of the waveguide 10 is perpendicular to the substrate B.
図６（ａ）に示すように、各電極２１、２２を逆符号（電極２１を正極、電極２２を負極）として、電極２１、２２間に電圧を印加すると、正極２１に接続された金属壁１１には正電荷が帯電し、負極２２に接続された金属壁１２には負電荷が帯電する。そうすると、一対の金属壁１１、１２にそれぞれ逆符号の電荷を帯電させることができ、金属壁１１、１２の間に働く静電引力により金属壁１１、１２が撓み、金属壁１１、１２同士を接近させることができる。 As shown in FIG. 6A, when the electrodes 21 and 22 are reversed (the electrode 21 is a positive electrode and the electrode 22 is a negative electrode) and a voltage is applied between the electrodes 21 and 22, the metal wall connected to the positive electrode 21 11 is charged with a positive charge, and the metal wall 12 connected to the negative electrode 22 is charged with a negative charge. Then, the pair of metal walls 11 and 12 can be charged with oppositely charged charges, and the metal walls 11 and 12 are bent by the electrostatic attractive force acting between the metal walls 11 and 12, so that the metal walls 11 and 12 are Can be approached.
また、図６（ｂ）に示すように、各電極２１、２２を同符号（電極２１および電極２２を正極または負極）として電圧を印加すると、一対の金属壁１１、１２にそれぞれ同符号の電荷を帯電させることができる。そうすると、金属壁１１、１２の間に働く静電斥力により金属壁１１、１２が撓み、金属壁１１、１２同士を離間させることができる。 In addition, as shown in FIG. 6B, when a voltage is applied with the electrodes 21 and 22 having the same sign (the electrodes 21 and 22 are positive or negative), the pair of metal walls 11 and 12 have the same charge. Can be charged. If it does so, the metal walls 11 and 12 will bend by the electrostatic repulsive force which acts between the metal walls 11 and 12, and the metal walls 11 and 12 can be spaced apart.
このように、本実施形態のプラズモン導波路素子２においても、金属壁１１、１２同士の間隔を自在に変化させて導波路１０の構造を変化させることができるので、導波路１０のプラズモン共鳴波長を変更でき、１つの素子で伝搬させる光の波長を自在に変更できる。また、金属壁１１、１２同士の間隔と導波路１０のプラズモン共鳴波長が変化することにより、導波路１０を構成する金属への光の吸収量が変化するので、１つの素子で光の伝搬距離を自在に変更できる。さらに、一対の金属壁１１、１２は、光の入射側または出射側の一方の端部が固定されており、他方の端部が可動となっているので、導波路１０を光の伝搬方向に先細りに変形でき、光を集光することで導波路１０の出射側端部の局所的な電場強度を入射光よりも増強できる。 As described above, also in the plasmon waveguide element 2 of the present embodiment, the structure of the waveguide 10 can be changed by freely changing the interval between the metal walls 11 and 12, so that the plasmon resonance wavelength of the waveguide 10 can be changed. The wavelength of light propagated by one element can be freely changed. In addition, since the amount of light absorbed by the metal constituting the waveguide 10 changes as the distance between the metal walls 11 and 12 and the plasmon resonance wavelength of the waveguide 10 change, the propagation distance of light by one element. Can be changed freely. Furthermore, the pair of metal walls 11 and 12 has one end on the light incident side or light exit side fixed, and the other end is movable, so that the waveguide 10 can be moved in the light propagation direction. The local electric field strength at the output side end of the waveguide 10 can be increased more than the incident light by condensing the light.
（その他の実施形態）
金属壁１１、１２同士を接近または離間させるアクチュエータとしては、金属壁１１、１２の間に働く静電引力または静電斥力を利用したもの以外にも、金属壁１１、１２に外力を働かせ、金属壁１１、１２同士を接近または離間させるアクチュエータを採用してもよい。
(Other embodiments)
As an actuator for bringing the metal walls 11 and 12 closer to or away from each other, an external force is applied to the metal walls 11 and 12 in addition to an actuator that uses electrostatic attraction or electrostatic repulsion acting between the metal walls 11 and 12. You may employ | adopt the actuator which makes the walls 11 and 12 approach or space apart.
つぎに、実施例について説明する。
（試料試験１）
まず、上記第１実施形態に係るプラズモン導波路素子１に相当する試料を作製した。
はじめに、真空蒸着装置を用いて、10-5Paの真空条件下で、厚さ1mmの石英ガラス基板（SiO2）上に厚さ3μmの金薄膜を成膜した。つぎに、集束イオンビームを用いて、表面側（金属薄膜側）からのみエッチングして、金属壁１１と金属壁１２との間の金属薄膜Ｍを除去するとともに、金属壁１１と電極２１との間、および金属壁１２と電極２２との間の金属薄膜Ｍを、接続部２３、２４を残すように除去することで、図１および図２に示すプラズモン導波路素子１の構造を作製した。ここで、金属壁１１、１２の厚さを200nm、高さ寸法を3μm、長さ寸法を10μm、金属壁１１と金属壁１２の間隔を300nmとした。接続部２３、２４の厚さを1.43μm、幅寸法を1μm、長さ寸法を10μmとした。また、電極２１、２２を100μm四方の矩形に形成した。
Next, examples will be described.
(Sample test 1)
First, a sample corresponding to the plasmon waveguide device 1 according to the first embodiment was manufactured.
First, a gold thin film having a thickness of 3 μm was formed on a quartz glass substrate (SiO 2 ) having a thickness of 1 mm under a vacuum condition of 10 −5 Pa using a vacuum deposition apparatus. Next, using a focused ion beam, etching is performed only from the surface side (metal thin film side) to remove the metal thin film M between the metal wall 11 and the metal wall 12, and between the metal wall 11 and the electrode 21. The metal thin film M between the metal wall 12 and the electrode 22 was removed so as to leave the connection portions 23 and 24, whereby the structure of the plasmon waveguide element 1 shown in FIGS. Here, the thickness of the metal walls 11 and 12 was 200 nm, the height dimension was 3 μm, the length dimension was 10 μm, and the distance between the metal wall 11 and the metal wall 12 was 300 nm. The thickness of the connection parts 23 and 24 was 1.43 μm, the width dimension was 1 μm, and the length dimension was 10 μm. Electrodes 21 and 22 were formed in a 100 μm square.
図７に、作製した試料を走査型電子顕微鏡で確認した結果を示す。
図７に示すように、所望の構造、寸法を有するプラズモン導波路素子を得ることができた。
FIG. 7 shows the result of confirming the produced sample with a scanning electron microscope.
As shown in FIG. 7, a plasmon waveguide element having a desired structure and dimensions could be obtained.
つぎに、図８に示す透過型顕微分光光学系を用いて、作製した試料に基板側から光を入射し、金属薄膜側から透過光を観側した。
より詳細には、顕微鏡下に試料を配置し、TM偏光保持した白色光を明視野系において照射した。
Next, using the transmission type microspectroscopic optical system shown in FIG. 8, light was incident on the manufactured sample from the substrate side, and the transmitted light was viewed from the metal thin film side.
More specifically, the sample was placed under a microscope and irradiated with white light with TM polarization maintained in a bright field system.
図９（ａ）に示すように、入射光の偏光方向を金属壁１１、１２が対向する方向とした場合、導波路１０から透過光が観測された。一方、図９（ｂ）に示すように、入射光の偏光方向を金属壁１１、１２に沿う方向とした場合、導波路１０から透過光が観測されなかった。以上にみられる偏光特性より、導波路１０において表面プラズモンが励起されることを確認した。 As shown in FIG. 9A, transmitted light was observed from the waveguide 10 when the polarization direction of the incident light was the direction in which the metal walls 11 and 12 face each other. On the other hand, as shown in FIG. 9B, when the polarization direction of the incident light is the direction along the metal walls 11 and 12, no transmitted light was observed from the waveguide 10. From the polarization characteristics seen above, it was confirmed that surface plasmons were excited in the waveguide 10.
つぎに、導波路１０からの透過光を紫外可視マルチチャンネル分光器により観測した。ここで、試料の電極２１、２２間には、ファンクションジェネレータを用いて1V刻みで0V〜10Vの電圧Vbを印加した。 Next, the transmitted light from the waveguide 10 was observed with an ultraviolet-visible multichannel spectrometer. Here, a voltage Vb of 0V to 10V was applied between the sample electrodes 21 and 22 in 1V increments using a function generator.
図１０に、上記透過型顕微分光光学系を用いて観測した印加電圧Vbを0、3、5、6、10Vとした場合おける透過光スペクトルを示す。また、図１１に、印加電圧Vbに対する透過光共鳴ピーク波長の関係を示す。
図１０および図１１に示すように、透過光共鳴ピーク波長は、印加電圧Vbが大きくなる（金属壁１１、１２同士の隙間が小さくなる）に従い長波長側へシフトすることが分かった。また、印加電圧が0Vの場合の短波長側に現れた第１ピークの波長は659.7nmであり、印加電圧が5Vの場合の第１ピークの波長は688.74nmであることから、5Vの電圧を印加すると透過光共鳴ピーク波長は約29nm（図１０における第１ピークの矢印に相当する。）シフトすることが分かった。また、その他のピーク波長も同様なレッドシフトの特性を示すとともに、第２、第３および第４ピークの波長はおおよそ周期的に表れていることが分かった。
Figure 10 shows the transmitted light spectrum definitive when the applied voltage V b was observed using the transmission type microscopic spectrometer optics and 0,3,5,6,10V. FIG. 11 shows the relationship between the transmitted light resonance peak wavelength and the applied voltage Vb .
As shown in FIGS. 10 and 11, it was found that the transmitted light resonance peak wavelength shifts to the longer wavelength side as the applied voltage Vb increases (the gap between the metal walls 11 and 12 decreases). The wavelength of the first peak that appears on the short wavelength side when the applied voltage is 0 V is 659.7 nm, and the wavelength of the first peak when the applied voltage is 5 V is 688.74 nm. When applied, it was found that the transmitted light resonance peak wavelength shifted by about 29 nm (corresponding to the first peak arrow in FIG. 10). It was also found that the other peak wavelengths showed similar red shift characteristics, and the wavelengths of the second, third and fourth peaks appeared approximately periodically.
（数値計算１）
つぎに、２次元有限差分時間領域法を用いた数値計算によりプラズモン導波路素子の光学特性を評価した。
図１２に示すように、数値計算におけるプラズモン導波路素子の構造を、SiO2基板上に金薄膜が形成された構造とした。ここで、金属壁１１、１２の厚さMWを300nm、高さ寸法Taを3.0μm、接続部２３、２４の厚さTbを1.0μmとした。また、作製した試料の金属壁１１、１２の先端形状は作製過程の影響から曲率を帯びていたことから（図７参照）、本数値計算においても金属壁１１、１２の角部の曲率半径Crを100nmとした。金属壁１１、１２の固定された端部（下端部）同士の間隔を固定端部間隔Gb、可動である端部（上端部）同士の間隔を可動端部間隔Gtとした。また、SiO2基板の屈折率を1.45とした。金の誘電率として、A.D.Rakicらの実験データ（Rakic, A. D., Djurisic, A. B., Elazar, J. M. & Majewski, M. L. Optical Properties of Metallic Films for Vertical-Cavity Optoelectronic Devices. Appl. Opt. 37, 5271-5283 (1998)）をドルーデ・ローレンツモデルで表現したものを用いた。
(Numerical calculation 1)
Next, the optical characteristics of the plasmon waveguide element were evaluated by numerical calculation using a two-dimensional finite difference time domain method.
As shown in FIG. 12, the structure of the plasmon waveguide element in the numerical calculation is a structure in which a gold thin film is formed on a SiO 2 substrate. Here, 300 nm thickness M W of the metal walls 11, 12, 3.0 [mu] m the height T a, was 1.0μm thickness T b of the connecting portions 23 and 24. In addition, since the tip shapes of the metal walls 11 and 12 of the prepared sample have a curvature due to the influence of the manufacturing process (see FIG. 7), the curvature radius C of the corners of the metal walls 11 and 12 also in this numerical calculation. r was set to 100 nm. The interval between the fixed end portions (lower end portions) of the metal walls 11 and 12 was defined as a fixed end portion interval G b , and the interval between movable end portions (upper end portions) was defined as a movable end portion interval G t . The refractive index of the SiO 2 substrate was 1.45. Experimental data of ADRakic et al. (Rakic, AD, Djurisic, AB, Elazar, JM & Majewski, ML Optical Properties of Metallic Films for Vertical-Cavity Optoelectronic Devices. Appl. Opt. 37, 5271-5283 (1998 )) Was expressed in the Drude Lorenz model.
プラズモン導波路素子の基板側からTM偏光させた光を入射した。入射光の偏光方向は金属壁１１、１２が対向する方向（x方向）とした。この入射光のスポット径（半値半幅）は、金属壁１１、１２が対向する方向（x方向）に1160nm、金属壁１１、１２に沿う方向（y方向）に無限とした。
そして、固定端部間隔Gbを300nmとし、可動端部間隔Gtを300nm〜2nmの間で変化させ、それぞれの条件における導波路からの透過光スペクトルを遠方解により算出した。
なお、２次元有限差分時間領域法におけるメッシュ間隔は、Gtが300、200、100、50nmのときは金属壁１１、１２が対向する方向（x方向）および金属壁１１、１２の高さ方向（z方向）にそれぞれ5nmとした。Gtが10、2nmのときは金属壁１１、１２間におけるメッシュ間隔を、x方向に1.0〜5.0nm、z方向に0.2〜5.0nmの不均一メッシュとした。
TM-polarized light was incident from the substrate side of the plasmon waveguide element. The polarization direction of the incident light was set to a direction (x direction) in which the metal walls 11 and 12 face each other. The spot diameter (half width at half maximum) of this incident light was 1160 nm in the direction (x direction) in which the metal walls 11 and 12 face each other and infinite in the direction along the metal walls 11 and 12 (y direction).
Then, the fixed end gap G b and 300 nm, the movable end gap G t varied between 300Nm～2nm, was calculated by far-field transmitted light spectrum from the waveguide in each of the conditions.
Note that the mesh interval in the two-dimensional finite difference time domain method is such that when G t is 300, 200, 100, or 50 nm, the metal walls 11 and 12 face each other (x direction) and the height direction of the metal walls 11 and 12. Each (z direction) was 5 nm. G t is the mesh spacing between the metal walls 11 and 12 when the 10,2Nm, was nonuniform mesh 0.2~5.0nm the x direction 1.0～5.0Nm, in the z-direction.
図１３に、数値計算により算出したプラズモン導波路素子の透過光スペクトルを示す。
図１３に示すように、短波長側に現れた第１ピークの波長は628.35nmであり、続いて第２、第３および第４ピークの波長がそれぞれ705.41nm、814.70nm、991.25nmであった。可動端部間隔Gtを300nm、10nm、2nmと変化させる（印加電圧が大きくなることに相当する）に従い、Gt=10nmおよび2nmの場合の第１ピークの波長は、それぞれ650.36nm、703.18nmと長波長側へシフトすることが分かった。また、その他のピーク波長も同様な特性を示した。さらに、第２、第３および第４ピークの波長はおおよそ周期的に表れており、また、電界強度分布からも反射部（固定及び可動端部）によるファブリー・ペロー共振であることを確認した。
以上のように、試料試験と数値計算の双方において、共鳴ピーク波長のレッドシフトとファブリー・ペロー共振が確認された。
FIG. 13 shows a transmitted light spectrum of the plasmon waveguide element calculated by numerical calculation.
As shown in FIG. 13, the wavelength of the first peak that appeared on the short wavelength side was 628.35 nm, and the wavelengths of the second, third, and fourth peaks were 705.41 nm, 814.70 nm, and 991.25 nm, respectively. . As the movable end interval G t is changed to 300 nm, 10 nm, and 2 nm (corresponding to an increase in applied voltage), the wavelengths of the first peak when G t = 10 nm and 2 nm are 650.36 nm and 703.18 nm, respectively. It turned out to shift to the long wavelength side. The other peak wavelengths showed similar characteristics. Further, the wavelengths of the second, third, and fourth peaks appear approximately periodically, and it was confirmed from the electric field intensity distribution that the Fabry-Perot resonance was caused by the reflecting portion (fixed and movable end portions).
As described above, the resonance peak wavelength red shift and Fabry-Perot resonance were confirmed in both the sample test and the numerical calculation.
以上より、本発明に係るプラズモン導波路素子が導波路のプラズモン共鳴波長を変更でき、１つの素子で伝搬させる光の波長を変更できることが明らかとなった。
なお、試料試験と数値計算において、透過光スペクトルに若干の違いが見られるが、これは、試料における金属壁の角の削れや、金属壁の厚み、高さ、ギャップなどの若干のばらつきに起因すると考えられる。
From the above, it has been clarified that the plasmon waveguide element according to the present invention can change the plasmon resonance wavelength of the waveguide and can change the wavelength of light propagated by one element.
Note that there is a slight difference in the transmitted light spectrum between the sample test and the numerical calculation. This is due to slight shaving of the metal wall corners in the sample and slight variations in the thickness, height, gap, etc. of the metal wall. I think that.
（数値計算２）
上記２次元有限差分時間領域法を用いた数値計算１において、固定端部間隔Gbを300nmとし、可動端部間隔Gtを300nm〜2nmの間で変化させ、電場強度の観測点における入射光の電場強度|Ei|に対する出射光の電場強度|Eo|を算出した。その余の条件は、数値計算１と同様である。
(Numerical calculation 2)
In numerical 1 using the two-dimensional finite-difference time-domain method, the fixed end gap G b and 300 nm, by varying the movable end gap G t between 300Nm～2nm, the incident light at the observation point of the electric field intensity The electric field intensity | E o | of the emitted light with respect to the electric field intensity | E i | The other conditions are the same as those in the numerical calculation 1.
その結果、図１４に示すように、特に可動端部間隔Gtが2nmの場合において、波長692.72nmにおける電場増強度（=|Eo|/|Ei|）は33となり、大きいことが確認された。光強度は電場強度の２乗に比例することから、入射光に対して出射光の強度が増強されることが確認された。なお、Crを0nm（金属壁１１、１２の先端形状に曲率を持たない）とした場合、電場増強度（=|Eo|/|Ei|）は〜60となり、非常に大きいことが確認された。
以上より、本発明に係るプラズモン導波路素子は、導波路１０の出射側端部の局所的な電場強度を入射光よりも増強できることを明らかにした。
As a result, as shown in FIG. 14, the electric field enhancement (= | E o | / | E i |) at a wavelength of 692.72 nm is 33, particularly when the movable end gap G t is 2 nm. It was done. Since the light intensity is proportional to the square of the electric field intensity, it was confirmed that the intensity of the emitted light is enhanced with respect to the incident light. Incidentally, when the C r and 0 nm (no curvature on the tip shape of the metal wall 11 and 12), the electric field enhancement (= | E o | / | E i |) is 60, and the is very large confirmed.
From the above, it has been clarified that the plasmon waveguide element according to the present invention can enhance the local electric field strength at the output side end of the waveguide 10 more than the incident light.
（試料試験２）
つぎに、上記試料試験１におけるプラズモン導波路素子の作製方法を改良して、試料を作製した。
はじめに、真空蒸着装置を用いて、10-5Paの真空条件下で、厚さ100nmの窒化珪素基板（Si3N4）上に厚さ1.46μmの金薄膜を成膜した。つぎに、集束イオンビームを用いて、裏面側（基板側）からエッチングして、金属壁１１と金属壁１２との間の金属薄膜Ｍおよび基板Ｂを除去した後、表面側（金属薄膜側）からエッチングして、金属壁１１と電極２１との間、および金属壁１２と電極２２との間の金属薄膜Ｍを、接続部２３、２４を残すように除去することで、プラズモン導波路素子の構造を作製した。ここで、金属壁１１、１２の厚さを200nm、高さ寸法を1.46μm、長さ寸法を10μm、金属壁１１と金属壁１２の間隔を300nmとした。接続部２３、２４の厚さを400nm、幅寸法を200nm、長さ寸法を10μmとした。また、電極２１、２２を100μm四方の矩形に形成した。
(Sample test 2)
Next, the method for producing the plasmon waveguide element in the sample test 1 was improved, and a sample was produced.
First, a 1.46 μm thick gold thin film was formed on a 100 nm thick silicon nitride substrate (Si 3 N 4 ) using a vacuum deposition apparatus under a vacuum condition of 10 −5 Pa. Next, etching is performed from the back side (substrate side) using a focused ion beam to remove the metal thin film M and the substrate B between the metal wall 11 and the metal wall 12, and then the surface side (metal thin film side). And the metal thin film M between the metal wall 11 and the electrode 21 and between the metal wall 12 and the electrode 22 is removed so as to leave the connection portions 23 and 24, so that the plasmon waveguide element is removed. A structure was made. Here, the thickness of the metal walls 11 and 12 was 200 nm, the height dimension was 1.46 μm, the length dimension was 10 μm, and the distance between the metal walls 11 and 12 was 300 nm. The thickness of the connection parts 23 and 24 was 400 nm, the width dimension was 200 nm, and the length dimension was 10 μm. Electrodes 21 and 22 were formed in a 100 μm square.
図１５に、作製した試料を走査型電子顕微鏡で確認した結果を示す。
図１５に示すように、所望の構造、寸法を有するプラズモン導波路素子を得ることができた。また、試料試験１の場合（図７参照）に比べて、金属壁１１、１２をなめらかな形状に形成することができた。具体的には、試料試験１の場合には金属壁１１、１２の頂部に凹凸が確認されたが、試料試験２の場合には金属壁１１、１２の頂部が真っ直ぐになっている。これは、金属壁１１、１２の間のエッチングを裏面側（基板側）から行うことで、表面側（金属薄膜側）からのエッチングが１回で済み、金属壁１１、１２の頂部へのビームの影響を少なくできたためと考えられる。
FIG. 15 shows the result of confirming the produced sample with a scanning electron microscope.
As shown in FIG. 15, a plasmon waveguide element having a desired structure and dimensions could be obtained. Moreover, compared with the case of the sample test 1 (refer FIG. 7), the metal walls 11 and 12 were able to be formed in the smooth shape. Specifically, in the case of the sample test 1, unevenness was confirmed on the tops of the metal walls 11 and 12, but in the case of the sample test 2, the tops of the metal walls 11 and 12 were straight. This is because etching between the metal walls 11 and 12 is performed from the back surface side (substrate side), and etching from the front surface side (metal thin film side) is completed once, and the beam to the top of the metal walls 11 and 12 is obtained. This is thought to be due to the fact that the effects of
つぎに、図８に示す透過型顕微分光光学系を用いて、作製した試料に基板側から光を入射し、導波路１０からの透過光を紫外可視マルチチャンネル分光器により観測した。
ここで、試料の電極２１、２２間には、ファンクションジェネレータを用いて1V刻みで0V〜10Vの電圧Vbを印加した。
Next, using the transmission type microspectroscopic optical system shown in FIG. 8, light was incident on the fabricated sample from the substrate side, and the transmitted light from the waveguide 10 was observed with an ultraviolet-visible multichannel spectrometer.
Here, a voltage Vb of 0V to 10V was applied between the sample electrodes 21 and 22 in 1V increments using a function generator.
図１６に、上記透過型顕微分光光学系を用いて観測した印加電圧Vbを0、2、4、6、8、10Vとした場合おける透過光スペクトルを示す。
図１６に示すように、透過光共鳴ピーク波長は、試料試験１の場合と同様に、印加電圧Vbが大きくなる（金属壁１１、１２同士の隙間が小さくなる）に従い長波長側へシフトすることが分かった。また、試料試験１の場合（図１０参照）に比べて、ピークの半値幅が狭くなり、ピークの数が少なくなる（波長400〜1,000nmの範囲で１つまたは２つのピーク）ことが分かった。ピークの波長は、金属壁１１、１２の高さにも依存する。試料試験２では金属壁１１、１２の頂部が滑らかであるため、高さ寸法が均一となっている。そのため、複数のピークが混在することなく、ピークの半値幅が狭くなり、ピークの数が少なくなると考えられる。このようにピークが鋭くなることで、透過光の波長の選択性が向上し、素子として扱いやすくなる。
Figure 16 shows the transmitted light spectrum definitive when the applied voltage V b was observed using the transmission type microscopic spectrometer optics and 0,2,4,6,8,10V.
As shown in FIG. 16, the transmitted light resonance peak wavelength shifts to the longer wavelength side as the applied voltage V b increases (the gap between the metal walls 11, 12 decreases), as in the case of the sample test 1. I understood that. In addition, it was found that the half width of the peak is narrower and the number of peaks is smaller (one or two peaks in the wavelength range of 400 to 1,000 nm) than in the case of the sample test 1 (see FIG. 10). . The peak wavelength also depends on the height of the metal walls 11 and 12. In the sample test 2, since the tops of the metal walls 11 and 12 are smooth, the height dimension is uniform. Therefore, it is considered that the half-width of the peak is narrowed and the number of peaks is reduced without mixing a plurality of peaks. By sharpening the peak in this way, the selectivity of the wavelength of transmitted light is improved and the device can be easily handled.
本発明に係るプラズモン導波路素子は、例えば、ナノ光集積回路を構成する素子として利用できる。ナノ光集積回路に用いた場合、エレクトロニクスと同等またはそれ以上の高速周波数応答が予想される。なお、表面プラズモンは、光の回折限界以下の領域に光エネルギーを閉じ込めることから、光デバイスをCMOS回路と同サイズに小型化する要素技術として利用でき、また単一試料での共鳴ピーク波長および伝搬距離の可変が可能であることから更なる高集積・高性能化が可能となる。具体的な応用としては、導波路、フィルタ、検出器、集光器などが挙げられる。さらに、入射光に対する出射側端部の局所的な電場増強を利用した局所センサとしても利用が可能である。また、一対の金属壁からなる導波路を電圧駆動のピンセットとして利用することで、任意の領域にある細胞や粒子、分子を高感度に検出など、次世代材料とデバイスへのアプローチすることが可能となる。 The plasmon waveguide element according to the present invention can be used, for example, as an element constituting a nano-optical integrated circuit. When used in a nano-optical integrated circuit, a high-speed frequency response equivalent to or higher than that of electronics is expected. Since surface plasmons confine optical energy in a region below the diffraction limit of light, it can be used as an elemental technology for downsizing optical devices to the same size as CMOS circuits, and the resonance peak wavelength and propagation in a single sample. Since the distance can be changed, higher integration and higher performance can be achieved. Specific applications include waveguides, filters, detectors, condensers, and the like. Furthermore, it can also be used as a local sensor using local electric field enhancement at the exit side end with respect to incident light. In addition, by using a waveguide consisting of a pair of metal walls as voltage-driven tweezers, it is possible to approach next-generation materials and devices, such as highly sensitive detection of cells, particles, and molecules in any region. It becomes.
１、２ プラズモン導波路素子
１０ 導波路
１１、１２ 金属壁
２１、２２ 電極
２３、２４ 接続部
DESCRIPTION OF SYMBOLS 1, 2 Plasmon waveguide element 10 Waveguide 11, 12 Metal wall 21, 22 Electrode 23, 24 Connection part
Claims (6)
前記金属壁同士を接近または離間させるアクチュエータと、を備える
ことを特徴とするプラズモン導波路素子。 A waveguide composed of a pair of metal walls disposed so as to face each other with a predetermined interval;
An plasmon waveguide element comprising: an actuator for bringing the metal walls closer to or away from each other.
ことを特徴とする請求項１記載のプラズモン導波路素子。 The actuator charges the pair of metal walls with opposite signs or the same sign, and moves the metal walls toward or away from each other by electrostatic attraction or electrostatic repulsion acting between the metal walls. The plasmon waveguide element according to claim 1, wherein
前記一対の金属壁の一方は、前記一対の電極の一方に接続されており、
前記一対の金属壁の他方は、前記一対の電極の他方に接続されている
ことを特徴とする請求項２記載のプラズモン導波路素子。 The actuator includes a pair of electrodes,
One of the pair of metal walls is connected to one of the pair of electrodes,
The plasmon waveguide element according to claim 2, wherein the other of the pair of metal walls is connected to the other of the pair of electrodes.
ことを特徴とする請求項３記載のプラズモン導波路素子。 4. The plasmon waveguide element according to claim 3, wherein the electrode and the metal wall connected to the electrode are arranged to face each other with a predetermined gap therebetween.
ことを特徴とする請求項１、２、３または４記載のプラズモン導波路素子。 5. The pair of metal walls, wherein one end portion on the light incident side or the light exit side is fixed, and the other end portion is movable. Plasmon waveguide element.
前記チップの基板側からエッチングして、導波路を構成する一対の金属壁の間の金属薄膜および基板を除去する工程と、
前記チップの金属薄膜側からエッチングして、金属壁と電極との間の金属薄膜を、接続部を残すように除去する工程と、を備える
ことを特徴とするプラズモン導波路素子の作製方法。 Forming a metal thin film on a substrate to obtain a chip;
Etching from the substrate side of the chip to remove the metal thin film and the substrate between the pair of metal walls constituting the waveguide;
Etching from the metal thin film side of the chip to remove the metal thin film between the metal wall and the electrode so as to leave a connection portion, and a method for producing a plasmon waveguide element.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2014099172A JP6376830B2 (en) | 2013-05-15 | 2014-05-13 | Plasmon waveguide device and manufacturing method thereof |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP2013102667 | 2013-05-15 | ||
| JP2013102667 | 2013-05-15 | ||
| JP2014099172A JP6376830B2 (en) | 2013-05-15 | 2014-05-13 | Plasmon waveguide device and manufacturing method thereof |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JP2014240957A true JP2014240957A (en) | 2014-12-25 |
| JP6376830B2 JP6376830B2 (en) | 2018-08-22 |
Family
ID=52140217
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP2014099172A Expired - Fee Related JP6376830B2 (en) | 2013-05-15 | 2014-05-13 | Plasmon waveguide device and manufacturing method thereof |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP6376830B2 (en) |
Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20030173647A1 (en) * | 2002-03-12 | 2003-09-18 | Montelius Lars G. | MEMS devices on a nanometer scale |
| JP2005221917A (en) * | 2004-02-09 | 2005-08-18 | Fuji Photo Film Co Ltd | Electromechanical type optical shutter element and optical shutter array |
| JP2006088202A (en) * | 2004-09-24 | 2006-04-06 | Nippon Telegr & Teleph Corp <Ntt> | Functional device, probe and scanning probe microscopy having probe, and manufacturing method of functional device and probe |
| JP2006330105A (en) * | 2005-05-23 | 2006-12-07 | Ricoh Co Ltd | Polarization control element and polarization control method of polarization control element |
| JP2008176127A (en) * | 2007-01-19 | 2008-07-31 | Toshiba Corp | Diffraction grating, light modulator, and display |
| JP2011099936A (en) * | 2009-11-04 | 2011-05-19 | Toyohashi Univ Of Technology | Subwavelength grating and display device |
| JP2012061528A (en) * | 2010-09-14 | 2012-03-29 | Yamaha Corp | Nanosheet transducer |
| JP2013178498A (en) * | 2012-02-08 | 2013-09-09 | Kagawa Univ | Plasmon chip |
-
2014
- 2014-05-13 JP JP2014099172A patent/JP6376830B2/en not_active Expired - Fee Related
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US20030173647A1 (en) * | 2002-03-12 | 2003-09-18 | Montelius Lars G. | MEMS devices on a nanometer scale |
| JP2005221917A (en) * | 2004-02-09 | 2005-08-18 | Fuji Photo Film Co Ltd | Electromechanical type optical shutter element and optical shutter array |
| JP2006088202A (en) * | 2004-09-24 | 2006-04-06 | Nippon Telegr & Teleph Corp <Ntt> | Functional device, probe and scanning probe microscopy having probe, and manufacturing method of functional device and probe |
| JP2006330105A (en) * | 2005-05-23 | 2006-12-07 | Ricoh Co Ltd | Polarization control element and polarization control method of polarization control element |
| JP2008176127A (en) * | 2007-01-19 | 2008-07-31 | Toshiba Corp | Diffraction grating, light modulator, and display |
| JP2011099936A (en) * | 2009-11-04 | 2011-05-19 | Toyohashi Univ Of Technology | Subwavelength grating and display device |
| JP2012061528A (en) * | 2010-09-14 | 2012-03-29 | Yamaha Corp | Nanosheet transducer |
| JP2013178498A (en) * | 2012-02-08 | 2013-09-09 | Kagawa Univ | Plasmon chip |
Also Published As
| Publication number | Publication date |
|---|---|
| JP6376830B2 (en) | 2018-08-22 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| Markovich et al. | Optical manipulation along an optical axis with a polarization sensitive meta-lens | |
| Andersen et al. | Hybrid plasmonic bullseye antennas for efficient photon collection | |
| Chen et al. | Electromechanically reconfigurable optical nano-kirigami | |
| Conrad et al. | A small-gap electrostatic micro-actuator for large deflections | |
| Zhou et al. | High-efficiency shallow-etched grating on GaAs membranes for quantum photonic applications | |
| Perahia et al. | Electrostatically tunable optomechanical “zipper” cavity laser | |
| Akihama et al. | Single and multiple optical switches that use freestanding silicon nanowire waveguide couplers | |
| US9182541B2 (en) | Graphene photonic device | |
| US20180031872A1 (en) | On-chip optical polarization controller | |
| JP4278597B2 (en) | Light control element | |
| Cai et al. | A nanoelectromechanical systems optical switch driven by optical gradient force | |
| JP6094961B2 (en) | Plasmon chip | |
| Lu et al. | Lithium niobate photonic crystal wire cavity: Realization of a compact electro-optically tunable filter | |
| Messner et al. | Broadband metallic fiber-to-chip couplers and a low-complexity integrated plasmonic platform | |
| JP6598184B2 (en) | COLOR FILTER, AND LIGHT EMITTING DEVICE AND DISPLAY DEVICE USING THE SAME | |
| US7474810B2 (en) | Method and apparatus for controlling light flux with sub-micron plasmon waveguides | |
| Pan et al. | Metallic nanowires for subwavelength waveguiding and nanophotonic devices | |
| US20080192327A1 (en) | Method and system for speckle reduction using an active device | |
| US7609932B1 (en) | Slot waveguide structure | |
| Nonahal et al. | Engineering quantum nanophotonic components from hexagonal boron nitride | |
| US20140090118A1 (en) | Probes for multidimensional nanospectroscopic imaging and methods of fabrication thereof | |
| JP6376830B2 (en) | Plasmon waveguide device and manufacturing method thereof | |
| Valente | Fabrication of planar nanomechanical photonic metamaterials | |
| Honma et al. | Free‐standing aluminium nanowire arrays for high‐transmission plasmonic colour filters | |
| Ng et al. | Design and fabrication of suspended indium phosphide waveguides for MEMS-actuated optical buffering |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| A621 | Written request for application examination |
Free format text: JAPANESE INTERMEDIATE CODE: A621 Effective date: 20170403 |
|
| A977 | Report on retrieval |
Free format text: JAPANESE INTERMEDIATE CODE: A971007 Effective date: 20180117 |
|
| A131 | Notification of reasons for refusal |
Free format text: JAPANESE INTERMEDIATE CODE: A131 Effective date: 20180123 |
|
| A521 | Request for written amendment filed |
Free format text: JAPANESE INTERMEDIATE CODE: A523 Effective date: 20180320 |
|
| TRDD | Decision of grant or rejection written | ||
| A01 | Written decision to grant a patent or to grant a registration (utility model) |
Free format text: JAPANESE INTERMEDIATE CODE: A01 Effective date: 20180717 |
|
| A61 | First payment of annual fees (during grant procedure) |
Free format text: JAPANESE INTERMEDIATE CODE: A61 Effective date: 20180724 |
|
| R150 | Certificate of patent or registration of utility model |
Ref document number: 6376830 Country of ref document: JP Free format text: JAPANESE INTERMEDIATE CODE: R150 |
|
| LAPS | Cancellation because of no payment of annual fees |