我們提出一個為期三年的研究計畫，擬以時間解析多光子發射電子顯微術直接觀測表面電漿子極化電荷分佈、動態場增強及能流漩渦誘發之異常穿透。由於表面電漿子是電磁波與表面集體震盪電荷相互耦合的一個特殊狀態，具有奈米級的空間尺度，現今大部分的主流研究是藉掃描式近場顯微術直接針對空間中的電磁場分佈進行量測。為瞭解表面電漿波傳輸性質的全貌，表面極化電荷的分佈將是一個重要的物理量。因此，毋須掃描、非侵入式、具高空間解析能力的光發射電子顯微術具有即時直接觀測電荷分佈的能力，可以補足掃描式近場顯微術無法直接量測到的物理量。透過表面電荷密度及能量密度的量測，我們可以決定波印亭向量的散度與旋度。根據亥姆赫茲定理，可以完整建構能量流的空間向量場。此外，結合激發-探測技術則可更進一步地作時間解析，建構能量流隨時間演進的動態行為。在為期三年的計畫中，我們將以實驗方式來驗證我們已有的數值模擬結果，其中包括量測馬克士威爾-加奈特(Maxwell-Garnett) 人造介質的光學非線性增強效應、電漿子環形共振腔轉角間共振誘發之簡併模分裂、以及光渦流誘發金屬次波長單狹縫之異常穿透現象。 We propose to directly visualize the polarization charge distribution, dynamical field enhancement, and power vortex induced extraordinary transmission based on time resolved multi-photon photoemission electron microscopy. Surface plasmon is a particular state consisting of the coupling between the incident electromagnetic wave and the collectively oscillated surface charges. Due to the capability of being confined within nano-sized dimension, most research so far heavily rely on the scanning near field optical microscopy (SNOM) to probe the electromagnetic energy distributions in spatial domain. However, to completely understand the transport property of surface plasmon waves, polarization charge distribution is no doubt an important physical quantity. Non-invasive scanning-free photoemission electron microscopy with extremely high spatial resolution enables the direct visualization of surface charge distributions in real time. This may effectively compensate the deficit of SNOM which can hardly measure the surface charges directly. With the charge density and the energy density measured, the divergence and curl of the Poynting vector can be determined. According to Helmholtz theory, the vector field of the power flow in spatial domain can be completely constructed. In addition, combining pump-probe technique, time evolution of the power flow can be established. In this three-year project, we plan to experimentally verify our existing simulation results which include the enhancement of optical nonlinear effect of manmade Maxwell-Garnett medium, degenerate modal splitting induced by intra-cavity corner-to-corner resonance in plasmonic ring resonators, and power vortex induced extraordinary transmission in subwavelength metallic single slit. 研究期間：10008 ~ 10107
