以金為基礎的奈米尺度超常介質之光學性質探討

Abstract

超常介質是週期性金屬結構，具有電漿子共振、人工磁性以及左手特性等，分別對應到某特定波長的電磁波在金屬陣列中傳遞時，材料所呈現的負導電係數(ε)、負導磁係數(μ)，及由此而造成的負折射率現象。 本論文利用電子束微影和舉離技術，成功地在玻璃上製造了線寬120至360奈米等級的三種金基共振還陣列：單裂隙共振環(split ring resonator, SRR)、無裂隙共振環(closed ring resonator, CRR)以及雙裂隙共振環(2-cut split ring resonator, 2-cut SRR)，圖形陣列面積大約是90 90μm2。傅式光學轉換紅外線光譜儀(FTIR)被用於研究超常介質所產生的光學性質。圖形尺度與電性共振頻率的關係，以及裂隙相對於電場的方位對三種共振環反射光譜的影響在本論文中被探討和比較。

Meta-materials are periodic metal structures exhibiting plasmonic resonance, artificial magnetism, and/or left-handed behaviors, which correspond to negative values of permittivity (ε), permeability (μ), and consequent refraction index (n), when electromagnetic (EM) waves propagate in these patterned arrays at a certain range of wavelengths. By using e-beam lithography and lift-off technique, three types of gold ring resonators with line width 120-360 nm were fabricated on glass. The area of the patterned array was about 90 90μm2. Fourier transfer infrared spectroscopy (FTIR) measurements were engaged for the study of optical properties of these meta-material structures. The properties of the electric resonance, such as scaling, were observed. The influence of the orientation of the ring resonators with respect to the incident electric field on the reflection spectra were also compared among different ring resonator structures.