具有多模態共振之電磁波複合超材料與其光學元件之應用

具有多模態共振之複合超材料(Composite metamaterials)豐富了材料本身的電磁特性，因此可以達到較複雜的光學功能以創造出具有實際光學應用價值的超材料。在這本論文中，第一個研究主題呈現了具有右手與左手電磁波特性的雙手超材料(Two-handed metamaterial)。在此，我們引進了兩種共振模態：磁偶極共振(Magnetic-dipole resonance)與類駐波腔體共振(Standing-wave-like cavity resonance)至單位結構上，用以產生右手與左手性質的電磁響應。延伸此一成果，在第二個研究主題中，我們組合了兩種不同類型的共振結構，藉此引入更多共振模態，用以組成複合超材料；並根據此複合超材料製造出兆赫波頻段的超寬頻帶通型濾波器(Ultra-broadband bandpass filter)，其頻寬可達0.5 THz，而厚度僅有38.4微米，因此可以整合在兆赫波光學微系統上；另外，我們也利用數值模擬方式證明，藉由調整其複合超材料的結構參數，使之搖身一變成為雙通道帶通型濾波器(Dualband bandpass filter)。在第三個研究主題中，我們也利用了另外兩種不同的共振結構來形成複合超材料，並整合其對於偏振光的轉換性與選擇性這兩種截然不同的電磁響應，設計出超薄型光偏振轉換器(Ultrathin polarization rotator)。此超材料光偏振轉換器之轉換效率高達97.7％，而其厚度僅有50.4微米，為相同功能之半波長石英波片的60分之一，大大縮小了元件的體積。這些以複合超材料製作之光學元件不僅擁有絕佳的性能，而在重量與體積上也更顯輕盈。這些優勢皆證明了具有多模態共振之複合超材料在光學元件與系統的應用上極具發展潛力！

關鍵字

超材料

並列摘要

Composite metamaterials (CMMs) with multiple resonant modes enrich their own electric and magnetic properties and hence can achieve complex optical functionalities. In this thesis, first, we realized a two-handed metamaterial that possesses right-handed and left-handed electromagnetic properties in the microwave region by introducing a magnetic-dipole resonance and a standing-wave-like cavity resonance into the unit structure of the metamaterial. Following this work, we combined two distinct resonant structures to form a CMM with multiple resonances for realizing a terahertz-wave ultra-broadband bandpass filter with a broad bandwidth of 0.5 THz and a papery thickness of 38.4 micrometers, so the filter is available for integration into terahertz-wave micro-optical systems. Besides, we also modulated the structure of the CMM to numerically demonstrate a high-profile dualband bandpass filter. In the third work, we further realized another CMM-based optical device: a 90-degree ultrathin polarization rotator (UTPR) with a nearly complete polarization conversion of 97.7 % for the terahertz-wave polarimetry, by integrating the polarization convertibility and the polarization selectivity from two distinct resonant structures. The thickness of the UTPR is only 50.4 micrometers, about 60 times thinner than a commercial half-wavelength quartz waveplates working at the same frequency. All of the CMM-based optical devices possess excellent performances and very compact structures. These substantial advantages demonstrate that CMMs with multiple resonant modes promise significant practical applications in optical devices.

並列關鍵字

Metamaterials

參考文獻

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[2]D. R. Smith, W. J. Padilla, D. C. Vier, S. C. Nemat-Nasser, and S. Schultz, “Composite medium with simultaneously negative permeability and permittivity,” Phys. Rev. Lett., vol. 84, pp. 4184-4187 (2000).

[3]R. A. Shelby, D. R. Smith, and S. Schultz, “Experimental verification of a negative index of refraction,” Science, vol. 292, pp. 77-79 (2001).

[4]D. R. Smith, J. B. Pendry, and M. C. K. Wiltshire, “Metamaterials and Negative Refractive Index,” Science, vol. 305, pp. 788-792 (2004).

[5]T. Koschny and M. Kafesaki, E. N. Economou, and C. M. Soukoulis, “Effective Medium Theory of Left-Handed Materials,” Phys. Rev. Lett., vol. 97. P. 103402 (2004).

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具有多模態共振之電磁波複合超材料與其光學元件之應用

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