| 研究実績の概要 |
In this research, a three-dimensional suspended nanofin-cavity structure consisting of metal-coated nanofins was designed and fabricated. Due to the coupling of plasmonic hot spots to the nanofin-cavities, strong optical flows turning light in a loop are sustained in the nanofin cavities and the optical properties of the nanofin-cavity structure change from being highly transparent to highly reflective at the resonance wavelength. Therefore, strong and tunable reflected resonances are realized in a very wide range from the NIR to IR region. A strong reflectance band can be tuned by varying the period of the nanofin cavities, and this presents a promising way to manipulate the nanofin cavities through the use of microsystems taking advantage of the suspended nanofin-cavity structure. In summary, a strong and narrow-band reflectance resonance due to the stringent condition of SPR arises with a bandwidth having a full width at half-maximum of 92 nm and a quality factor as large as 60 from the NIR to IR region using different order modes and also tunability by varying the period of the nanofins. Although this study concentrated on the filtering and switching properties in the IR and NIR region, which are of major interest for studying the fingerprint region and biosensing, the nanofin-cavity structure can be designed to suit the requirements of many other applications in the visible to the terahertz regions. The characteristics of the nanofin-cavity structure provide a new way to design band-pass filters, optical switches, sensor, and applications in the fingerprint region.
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