週期性U形及H形金屬孔洞之異常穿透特性研究

The Extraordinary Transmission through Periodic U- and H-shaped Hole Arrays

黃浩菔(Hao-Fu Huang)

指導教授 ： 李嗣涔

國立臺灣大學/電機資訊學院/電子工程學研究所/碩士(2010年)

https://doi.org/10.6342/NTU.2010.02296

摘要

本文在實驗上觀察周期性U與H形狀金屬孔洞的異常穿透特性。本文第一個主題利用U形狀孔洞研究當孔洞之共振長度超過孔洞周期時的穿透頻譜。藉由將矩形孔洞彎曲為U形,吾人可以而在固定的孔洞周期長度中放入較長的矩形洞。本文也觀察孔洞的形狀與大小的效應。對於孔洞形狀為矩形或是U形的樣品而言，穿透頻譜不會總是由表面電漿模態所控制。侷域性的形狀共振模態出現並且影響穿透機制。吾人藉由改變U形孔洞的共振長度來探討表面電漿模態與侷域形狀共振模態之間的轉換。當侷域形狀共振模態波長接近表面電漿模態波長時，表面電漿模態會被激發。當共振長度不斷增加時，二階侷域形狀共振模態會出現在穿透頻譜。當孔洞不斷增大，二階侷域形狀共振模態波長接近表面電漿模態波長時，表面電漿模態會被激發。侷域形狀共振模態與表面電漿模態會共存於穿透頻譜之上。第二個主題則探討H形以及由多個U形組成的孔洞形狀之穿透頻譜研究，實驗顯示侷域形狀共振模態的共振腔長度是由孔洞的U形部分展開後的總長度決定。與較小之孔洞U形部分有關的侷域形狀共振模態不會總是出現在穿透頻譜。而擁有最大之孔洞U形部分的侷域形狀共振模態會在所有實驗上都觀察到。非U形共振路徑的侷域形狀共振模態在穿透上皆未被觀察到。此外，不同方向的極化光可以激發不同模態的侷域形狀共振模態。

關鍵字

表面電漿 ； 形狀共振

並列摘要

The extraordinary transmission through a metal film perforated with periodic U and H shape hole array in far-infrared region are demonstrated. In first part of this thesis, U-shaped hole is used to studied the transmission when the resonance length of the hole exceed the hole period. The longer rectangular hole can be design in the fixed period by ‘bending’ the rectangle into U shape. The influence of hole shape and hole size are demonstrated. For the sample with rectangular or U-shaped hole, the transmission mechanism is not always dominated by surface plasmon (SP).The localized shape resonance (LSR) appears and affects the transmission mechanism. The U shape hole array is used to investigate the transition between SP and LSR by changing total resonant length of U shape hole. 2nd LSR appears as the resonant length continuously increase. When resonant wavelength of 2st LSR is close to the SP , SP mode can be excited. The SP and LSR coexist in transmission spectra when the hole is enlarged. In second part of this thesis, the transmission spectra through samples with periodic H-shaped hole and more complicated hole which is a combination of multiple U shape are investigated. The observations indicate that the resonant length of localized shape resonance is the length of unfolded U-shaped part of the hole. LSR modes with smaller resonant U-shaped length don't always appear. The transmission spectra reveal that the LSR mode with largest resonant U-shaped part of the hole could always be observed. In addition, LSR mode with non-U-shaped resonant path cannot be seen in our sample. In addition,The transmission spectra with different polarization reveal that LSR with different order and resonant path can be excited by different polarized light.

並列關鍵字

surface plasmon ； shape resonance

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