金屬-介質-金屬波導結構的表面電漿分光器之研究

Abstract

本篇論文提出一新型的表面電漿能量分光器，並且使用二維有限時域差分法來分析元件之效能。首先，探討一矩形環狀波導結構之長度和寬度與輸出波導之間的間距對於輸出功率、反射率和分光比的影響。以一三個輸出波導結構為例，我們發現在固定輸出波導間距下，其輸出波導間分光比並不因矩形環狀波導之邊長改變而有所影響。但是，輸入波導端之反射率值會隨著矩形環狀波導之邊長改變而有所改變。在固定間距下，我們並無法透過更改矩型結構之邊長來獲得零反射率，因此我們在輸入波導及矩型結構間嵌入一抗反射層結構，以期降低反射率至零。根據這些觀察，我們發展出此能量分光器之設計流程，並且提出一分二、一分三和一分四能量分光器這三例子來驗證。其模擬結果顯示著這些元件之反射率皆可降至小於0.1%，且其作用波長範圍可以涵蓋整個S+C+L頻區。

In this thesis, we propose novel power splitters based on MIM plasmonic waveguides, and use the two-dimensional finite difference time domain method to analyze this structure. First, we investigate the influences of the length and width of a rectangular ring resonator structure and the distances between output waveguides on the output powers、the power ratios between output ports and the reflection. Take an example of a ring resonator with three output ports. We find that the power ratios between output ports are approximately unvaried as the length and width of the resonator structure change. However, the reflection varies with the variation of the dimension of the resonator structure but could not always be reduced to zero as the distances between the output ports are fixed. Hence, an antireflection resonator structure is essential to be embedded in-between the input waveguide and the resonator structure. Based on these observations, we develop a design flow to determine the design parameters of our proposed device and take three design examples of 1×2, 1×3 and 1×4 power splitters to illustrate the design concepts. The simulation results show that these components have the reflection of less than 0.1% and can be operated at the wavelength ranging of the S+C+L bands. These devices possess the advantages of compact sizes, low insertion loss and wide operation wavelength.