| 研究課題/領域番号 |
26289013
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| 研究機関 | 東京大学 |
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研究代表者 |
J・J Delaunay 東京大学, 工学(系)研究科(研究院), 准教授 (80376516)
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| 研究分担者 |
三田 吉郎 東京大学, 工学(系)研究科(研究院), 准教授 (40323472)
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| 研究期間 (年度) |
2014-04-01 – 2017-03-31
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| キーワード | ナノマイクロ加工 / メタマテリアル・表面プラズモン |
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| 研究実績の概要 |
The main goal of this research project is to design and fabricate a miniaturized infrared spectrometric image-array-sensor using a new plasmonic nanostructure. The new plasmonic nanostructure consists of periodic high-aspect-ratio semiconducting walls sandwiched between metallic layers forming a U-cavity. In the first year of the project, we have designed the plasmonic structure consisting of semiconducting channel sandwiched between metal layers. This hybrid cavity-channel structure achieves absorption resonance with a bandwidth of as narrow as 1.5 nm. Furthermore, the absorption resonance of the designed structure is tunable in the near-infrared and infrared regions. Therefore, the proposed hybrid structure can be made to absorb light selectively in the infrared region and a spectrometric image array sensor should be possible to fabricate. Finally, the mechanism of the spectrally selective light absorption in the hybrid structure was clarified. The absorption resonance originates in the coupling of horizontal surface plasmon mode of the U-cavity with channel mode. The channel mode sustains stationary-surface-plasmons in the channel with antinodes at the channel entrances enabling light concentration and nodes at the channel exits enabling light confinement. As a result of the coupling, a sharp and strong absorption resonance is readily adjustable by varying the geometrical parameters of the U-cavity. The hybrid structure sustains sharp, strong and controllable resonances that realize both dispersion and detection of infrared light, thus is amenable to miniaturization.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
We have reported a very sharp and tunable absorption peak and provided details for the design and mechanism of these absorption peaks. Our results have already been published: “Plasmonic Hybrid Cavity-Channel Structure for Tunable Narrow-Band Optical Absorption,” Photonics Technology Letters, 26, 1979, 2014. We have also attempted to fabricate a sample and have obtained encouraging results, although the fabrication technique still needs to be improved and is different from the initial research plan. We are currently building the setup for the evaluation of the properties (optical and electrical) of our fabricated samples. The optical characterization has been started in the first year so that we should be able to complete it in the second year of the project. However the electrical characterization has not yet been started.
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| 今後の研究の推進方策 |
In the second year, effort will be made to establish a reliable fabrication technique of our structure and also evaluate the physical properties of the structure. Particularly, we need to modify the original proposed fabrication technique to be able to obtain a silicon channel embedded in gold layers and demonstrate the reliability of the new fabrication technique. The optical and electrical properties will be measured. As for the optical properties, the current setup based on a fast-Fourier reflectance spectrometer needs additional improvements such as a more sensitive detector and a larger range of measurement. Using the improved optical setup, the absorption peaks of the fabricated structure will be characterized. Our goal is to achieve a full width at half maximum below 10 nm (top data) and also to demonstrate the tunability of the structure over a large range of wavelengths. For the electrical properties of the samples, a setup will be built so that the impedance of our samples can be measured. Our goal is to demonstrate that the fabricated sample shows the correct impedance behavior.
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| 次年度使用額が生じた理由 |
One of the steps of the fabrication technique involving ion milling required a vacuum chamber and sample stage for which we have employed used parts and therefore could save money to purchase needed equipment for the sample optical and electrical characterizations.
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| 次年度使用額の使用計画 |
In the second year of the project, the fund will be used to cover the sample fabrication cost at the Takeda center, to maintain our simulation tools, to improve the optical setup and to build an electrical setup. Particularly, we need to improve our optical setup (change the detector of the spectrometer, add a polarizer) and also build an electrical setup to measure the impedance of our device (impedance meter is needed).
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