研究期間：10108~10207;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.
