| Project/Area Number |
17560313
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Electron device/Electronic equipment
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| Research Institution | Kumamoto University |
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Principal Investigator |
OKUNO Yoichi Kumamoto University, Graduate School of Science and Thchnology, Professor (50117082)
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| Co-Investigator(Kenkyū-buntansha) |
SUYAMA Taikei Kumamoto University, Graduate School of Science and Technology, Assistant Professor (70336204)
MATSUDA Teyonori Kumamoto National College of Technology, 情報通信工学科, Professor (00157322)
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| Project Period (FY) |
2005 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,340,000 (Direct Cost: ¥3,100,000、Indirect Cost: ¥240,000)
Fiscal Year 2007: ¥1,040,000 (Direct Cost: ¥800,000、Indirect Cost: ¥240,000)
Fiscal Year 2006: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2005: ¥1,100,000 (Direct Cost: ¥1,100,000)
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| Keywords | metal grating / plasmon resonance-absorption / Refractive Index Measurement / conical mount / concentration sensor / 屈折率測定 / コニカル配置 / TM-TEモード変換 |
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| Research Abstract |
We investigate numerically plasmon-resonance absorption in a metal grating in conical mounting, where the plane of incidence is not perpendicular to the grating grooves. Unlike in the case of planar mounting, in which the plane is perpendicular to the grooves, the absorption occurs for both TE- and TM- incidence. The angle at which the absorption occurs agrees with a resonance angle predicted by the phase-matching condition for the coupling of an evanescent mode with surface plasmons. In addition, strong enhancement of TE-TM (or TM-TE) mode conversion between the incident and the reflected light is observed at the resonance angle. Dependence of the conversion efficiency on the azimuth angle and the grating depth is studied in detail.
We carried out numerical calculations of diffraction by a metal grating placed in planar or conical mounting and examined excitation of surface plasmons in detail. We compared most of the numerical results with experimental data. In our experiment we used a
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commercial UV grating made of Al with a thin Au over-coating, whose parameters were employed in numerical simulation. In the planar mounting we observed typical plasmon-resonance absorption for TM-wave incidence in both numerical results and experimental data, which agreed well with each other.
In the conical mounting we found strong TM-TE mode conversion in addition to the absorption. For TM-wave incidence the TM-component of the diffracted wave almost vanished and the TE-component was dominant in close vicinity to the resonance angle. The reciprocal of the TM-wave efficiency having a sharp peak at the resonance angle, hence, could be a practical measure in finding the angle. Results of a preliminary experiment confirmed that we could find the angle to 0.1 degree accuracy. If we apply the resonance absorption to an index sensor, the accuracy means four digits determination of the refractive index of a material over the grating surface.
In addition, possibility of precise index measurement by the optimization of the azimuth angle in conical mounting was examined. If the accuracy in the indices of metals could be secured and if necessary precision in the experiment could be insured, determination of the index to more than four digits would be achieved without much trouble. Less
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