本論文設計一方向耦合結構的電漿子開關，其光訊號在電漿子(Plasmonic)波導與矽(Si)光波導之間進行轉換，電漿子開關元件特性包括傳播長度(Propagation Length)、操作電壓(Operated Voltage)、透射率(Transmittance)、插入損耗(Insertion Loss)、隔離度(Isolation)、消光比(Extinction Ratio)，透過改變材料與設計最佳化結構尺寸來優化這些參數。
本論文以謝政宏學長於2015年在IEEE發表的方向耦合結構電漿子開關為基礎，提出材料變換，首先改變電漿子波導的介電質材料，將對甲苯磺酸鹽(DAST)改變為二氧化釩(VO2)，可以直接搭配矽光波導達到相位匹配的效果，藉由二氧化釩在外加電壓後會產生相變的物理機制，可以控制此元件的開與關。本文透過研究傳播長度與操作電壓的變化趨勢，分析出最佳化的二氧化釩與銀(Ag)厚度，接著透過相位匹配分析，找出對應的兩波導寬度，最後透過插入損耗與隔離度的變化趨勢，分析出最佳化的耦合長度，經過以上模擬結果，可以分析出最佳化的結構尺寸。
本論文透過改變材料與設計最佳化結構尺寸後，大幅度地提升電漿子開關的效能表現，關與開狀態的透射率分別維持在55 %與60 %，所佔面積從原本的29.4 µm大幅縮減到2.05 µm，操作電壓從22.5 V降低到9.65 V，隔離度從10 dB提升到14 dB，消光比從10 dB提升到41 dB，改善超過3個數量級。

This paper design and analyze a directional coupler structure based plasmonic switch. The optical signal is converted between the plasmonic waveguide and the silicon optical waveguide. The characteristics of the plasmonic switch including propagation length, operated voltage, transmittance, insertion loss, isolation and extinction ratio. Through changing material and designing optimized structural dimensions to optimize above characteristics.
On the basis of directional coupler structure based plasmonic switch of Cheng-Hung Hsieh’s IEEE paper . This paper attempts to change the material. First, change the dielectric material of the plasmonic waveguide, DAST to vanadium dioxide(VO2).After the voltage is applied on the vanadium dioxide, vanadium dioxide’s phase will change. This physical mechanism can control the on and off state. In this paper, through studying the variation trend of propagation length and operated voltage to analysis the optimized thickness of vanadium dioxide and silver. Then, through phase matching to find the corresponding two waveguide widths. Finally, through studying the variation trend of insertion loss and isolation to analysis the optimized parallel length. After the above simulation results, the optimized structural dimensions can be designed.
After changing the material and designing optimized structural dimensions, the paper greatly improved the performance of the plasmonic switch. The transmittances of the off and on states are maintained at 55 % and 60 %, respectively. The footprint was greatly reduced from the original 29.4 μm to 2.05 μm. The operated voltage is reduced from 22.5 V to 9.65 V. The isolation is increased from 10 dB to 14 dB, and the extinction ratio is increased from 10 dB to 41 dB, improving by more than 3 orders of magnitude.

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