表面聲波對電漿子波導特性之探討

Investigation of Surface Acoustic Wave induced Plasmonic Responses in the Waveguide

李亮昀(Liang-Yun Lee)

指導教授 ： 黃建璋

國立臺灣大學/電機資訊學院/光電工程學研究所/碩士(2023年)

https://doi.org/10.6342/NTU202303071

摘要

本研究提出了一種新穎的方法，透過將表面聲波（SAW）結合到混合電漿子波導的結構中，以增強元件上的表面電漿子信號。電漿子波導具有實現次波長限制和增強信號傳播的潛力，但在能量限制和傳播距離方面仍存在挑戰。為了解決這些問題，本研究提出使用表面聲波（SAW）作為外部機制來放大和調節傳播中的表面電漿子。
我們所提出的結構由半導體-金屬-絕緣體-半導體（SMIS）波導和交指叉狀轉換器（IDT）組成其可用於產生表面聲波（SAW）。並在鋰鈮酸鋰（LN）基板上利用金-二氧化矽（Au-SiO2）界面來激發表面電漿子並促使其傳播。通過對IDT施加外部交流電壓，表面聲波可以使得結構中的折射率發生改變，從而增強和控制電漿子信號的強度。
第一部分我們通過實驗結果證明，透過單一設備在特定交流訊號之峰對峰的電位下提供外部表面聲波的增益，可以顯著增強表面電漿子的強度。這種表面電漿子的放大類似於傳統通訊系統中中繼器的功能，能夠實現增強的信號傳輸和在更長距離上的傳播。
第二部分研究同向和反向傳播的表面聲波與表面電漿子-電磁極化子的相互作用，並討論表面聲波產生的聲子對表面電漿子強度的影響，本研究旨在闡明聲子、光子和表面電漿子之間的相互作用。這些研究結果對於設計和優化元件上表面電漿子設備具有重要的潛力，並在高靈敏度生物傳感和遠距離電漿子通訊等多個領域中提供了應用的可能性。

關鍵字

表面電漿子 ； 光子 ； 聲子 ； 表面電漿子-電磁極化子 ； 混合電漿子波導 ； 表面聲波 ； 交指叉狀轉換器

並列摘要

This study presents a novel approach to enhance on-chip plasmonic signals by integrating surface acoustic waves (SAWs) into a hybrid plasmonic waveguide structure. Plasmonic waveguides have shown promise for enabling subwavelength confinement and enhanced signal propagation, but they still face challenges in terms of limited energy confinement and short propagation length. To address these issues, this study proposes the use of SAWs as an external mechanism to amplify and modulate propagating plasmons.
The proposed structure consists of a semiconductor-metal-insulator-semiconductor (SMIS) waveguide and an interdigital transducer (IDT) for generating SAWs. The gold-silicon dioxide (Au-SiO2) interface on a Lithium Niobate (LN) substrate is utilized to excite surface plasmons and facilitate their propagation. By applying an external AC voltage to the IDT, the SAWs can modify the plasmonic confinement and intensity, providing a means to enhance and control the strength of the plasmonic signal.
Through experimental findings, it has been demonstrated that a single device providing an external SAW gain at a specific AC peak-to-peak potential can significantly increase the strength of surface plasmon. This amplification of surface plasmons is akin to the function of repeaters in conventional communication systems, enabling enhanced signal transmission and propagation over longer distances.
By investigating the interaction between SAWs and Surface Plasmon Polaritons (SPPs) under co-directional and counter-directional propagation, as well as the influence of phonons generated by SAWs on SPP intensity, this study aims to explain the dynamics and interplay between phonons, photons, and surface plasmons. The findings from this research can provide valuable insights into the design and optimization of on-chip plasmonic devices, opening up possibilities for applications in various fields, including high-sensitivity biosensing and long-distance plasmonic communication.

並列關鍵字

Surface plasmon ； Photons ； Phonons ； Surface plasmon polariton ； Hybrid plasmonic waveguide ； Surface acoustic wave ； Interdigital transducer

參考文獻

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