遠紅外波段下二維金屬孔洞型微共振腔之研究

Abstract

本論文研究在遠紅外波段中，二維金屬孔洞陣列-絕緣體-金屬結構形成的微共振腔結構，其吸收特性與物理機制。藉由量測微共振腔反射率頻譜，我們觀察共振吸收強度與共振頻率譜隨孔洞形貌與孔洞大小的變化，發現兩種不同的共振吸收特性。隨正方形孔洞變大，我們發現共振吸收頻率發生藍移現象。而隨著長方形孔洞長寬比逐漸變高，共振吸收頻率則會紅移。我們將此現象歸因於共振異常穿透與異常穿透的共振機制與金屬-絕緣體-金屬結構形成的共振機制。此外，透過觀察共振腔內的電場場形，我們得以定性的分析特徵谷的強度會隨圖案的形貌與大小變化的趨勢；原因推測是階數的差異以及背金板增強電場所造成。

This thesis studies the absorption characteristics and physic of microcavities with two-dimensional metallic hole array in the far infrared regime. We find two different resonant absorption characteristics by observing the changes in absorption intensity and resonance frequency with the shape and size of the holes . For square holes, the resonance frequency exhibits a blueshift as dimension of the square holes increases. For rectangular holes, the resonance frequency has a redshift as the aspect ratio of the rectangle holes gradually increases. We attribute the mechanism underlying the frequency shift to the resonance due to extraordinary optical transmission and cavity-resonance within metal-insulator-metal microcavities. In addition, we analyze qualitatively the variation in the resonant absorption intensity with the hole patterns and sizes by observing the electric field pattern in the cavity, which is attribute the mode difference and presence of the backside metal.