發展三維有限差分時域數值模型研究數種感測應用的奈米金屬結構

本篇論文中，我們使用 C 程式語言發展了三維有限差分時域電磁計算數值模型，並且透過訊息傳遞介面協定，發展具有平行化功能的模型以減少運算時間。我們的研究主要在使用所發展的數值模型進行模擬，分析數種奈米電漿子結構應用在感測環境光折射率變化的特性。在第一部分，對開口環形共振腔做透射頻譜的計算，得到了共振波長，因此可以計算其對環境變化的感測度。然後我們可以發現平躺的開口環形共振腔比直立的效率低，因為有電磁場進入了基板內部，降低了感測的能力。但在製程上來說，直立的結構會比平躺的製造困難。因此我們嘗試改變平躺的開口環形共振腔形狀，做了許多不同結構，最後得到的平躺結構可以得到高達 950 奈米/單位折射率的感測度，比原本直立的開口環形共振腔高。在第二部分，我們研究領結天線與多段轉折奈米天線結構，這幾種結構常被拿來用作為增強電場強度的天線。我們對它們做透射頻譜分析，可以得到共振波長和對環境的光感測度，在大約 1200 奈米的共振波長範圍，發現它們也有不錯的效率，雖然較上一部份的開口環形共振腔低。然而有些天線在超過 2000 奈米的波長範圍有其他模態的共振，可以得到超過 1000 奈米/單位折射率的感測度。

關鍵字

有限差分時域法；電漿子；開口環形共振腔；感測器；奈米天線

並列摘要

In this thesis, a parallelized three-dimensional (3-D) finite-difference time-domain (FDTD) method numerical simulator is developed by using the message passing interface (MPI) library code in C language. The main topic of this research is to analyze the sensitivities of several nano-plasmonic structures when applied to sense substances of different refractive indices using the FDTD simulators. In the first part, the transmittance spectra of the split-ring-resonators (SRRs) are simulated and the resonance wavelength with corresponding sensitivities obtained. Then we can obtain their resonance wavelength and calculate the sensitivity. Planar split-ring resonators (PSRRs) may be less efficient than their vertical counterparts because plasmon fields of the former may spread into the substrate and reduce the sensing ability. With the view that PSRRs are less difficult in fabrication, they are varied in structure geometry numerically to find higher sensitivity. High sensitivity up to 950 nm/RIU is obtained, which can be better than that of the vertical SRRs. In the second part, the bowtie and multi-bend-section nano-antenna (MBSNA) structures which are used in field enhancement application are studied. Over the same resonance wavelength range (around 1200 nm), their sensitivities are found to be worse than the SRRs. But some of them possess another mode with larger resonance wavelength exceeding 2000 nm and can give larger sensitivity up to 1000 nm/RIU.

並列關鍵字

Finite-diﬀerence time-domain method ； surface plasmons ； split-ring-resonators ； sensors ； nano-antennas

參考文獻

Albani, M., and P. Bernardi, "A numerical method based on the discretization of Maxwell equations in integral form," IEEE Trans. Microwave Theory Tech., vol. 22, pp. 446-450, 1974.

Atwater, H. A., and A. Polman, "Plasmonics for improved photovoltaic devices," Nat. Mater., vol. 9, pp. 205-213, 2010.

Berenger, J. P., "A perfectly matched layer for the absorption of electromagnetic waves," J. Comput. Phys., vol. 114, pp. 185-200, 1994.

Courant, R., K. Friedrichs, and H. Lewy, "Uber die partiellen differenzengleichungen der mathematischen physik," Math. Ann., vol. 100, pp. 32-74, 1928.

Dmitriev, A., C. Hagglund, Si Chen, H. Fredriksson, T. Pakizeh, M. Kall, and D. S. Sutherland, "Enhanced nanoplasmonic optical sensors with reduced substrate effect," Nano Lett., vol. 8, pp. 3893-3898, 2008.

國際替代計量

發展三維有限差分時域數值模型研究數種感測應用的奈米金屬結構

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