Prof. Cheng Sun
Department of Mechanical Engineering,
Northwestern University, USA
时间：2015年6月25日 星期四 下午 3:30
地点：唐仲英楼 B501
报告简介：
"Exploring the Coupled Photonic and Phononic Phenomena Using Nanophotonic Metasurfaces"
Cheng Sun
Department of Mechanical Engineering, Northwestern University, Evanston IL 60208
The emerging field of metamaterials/metasurfaces has attracted considerable interest in the field of nanotechnology. Metamaterials or metasurfaces are the assemblies of rationally designed sub-wavelength-scale “Meta-atoms” that feature non-natural occurring properties, and their unique ability to manipulate electromagnetic waves have therefore inspired many fascinating applications, such as artificial magnetism for magnetic resonance imaging (MRI) and sub-diffraction limited imaging. It is worthwhile to note that their extraordinary properties are engineered through structure rather than through their constituting materials and thus, offers an extremely flexible platform for active control of materials properties such as switching and modulation of electromagnetic waves. I’ll present a few recent experiments that explore the unique properties of the nanophotonic metasurface exhibiting artificial magnetism at optical frequency.
This talk is focusing on exploring the strongly coupled photonic and phononic phenomena using the novel optomechanical metasurface. The mechanistic understanding of the coupled phenomena can then be broadly applied to broader electromagnetic spectrum. A monolayer metasurface comprising a large array of metallic U-shaped nanowire resonators (UNWRs) is first developed to achieve strongly confined photonic mode through the excitation of the magnetic resonance at the optical frequency. Controlling the coupling among the neighboring artificial magnetic moments, distinct arrangement of artificial “ferromagnetism” and “antiferromagnetism” at optical frequency can be further realized. Finally, the U-shaped structure with two free-standing also supports mechanical vibration at GHz that spatially overlap with the magnetic resonance. Based on the co-localized optical response and mechanical resonance in deep-subwavelength volume, this metasurface will be utilized as an optomechanical system to explore the coupled photonic and phononic modes at nanoscale.