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Research Highlights (研究亮点)

SNOM development (近场光学显微技术发展): Scanning near-field optical microscope (SNOM), the marriage between optical spectroscopy and scanning probe microscopes, has been progressively perfected as a powerful nano-imaging and nano-spectroscopy tool in the last decade. We aim to further expand the capabilites of SNOM by: (1) integrating SNOM with ultrafast optical spectroscopy to allow nanoscale spatial resolution and ultrafast (ps to fs) temporal resolution ; (2) interfacing SNOM with versatile nano-electrical and nano-mechanical mapping methods to achieve a  multifunctional scanning probe platform. 

Quantum plasmonics (量子等离体激元): Surface plasmons, collective electromagnetic excitations coupled to conduction electron oscillations, enable the manipulation of light-matter interactions at the nanoscale. Conventional plasmons suffer from the trade-off between extreme spatial confinement and low loss.  We explore the possibilities of alleviating this dilemma by means of quantum effects (quantum plasmonics) and topological effects (topological nanophotonics) in unconventional plasmonic systems, including carbon nanotubes and topological semimetals. 

Carbon nanotubes (碳纳米管): Single walled carbon nanotubes (SWNTs) are 1D rolled-up hollow cylinders composed of graphene sheets. Despite the intense established research in the last three decades,  SWNTs ——long touted as beyond-silicon alternatives —— have never ceased to surprise researchers with their emerging properties and potential applications. We leverage state-of-the-art surface characterization tools to probe the Luttinger liquid physics and excitonic effects in ultraclean metallic and semiconducting carbon nanotubes. 

van der Waals heterostructures (范德华异质结构): van der Waals heterostructures are composed of individual atomic layers bonded by the weak van der Waals force. The vast palette of low-dimensional single crystals and the powerful tuning knobs including twist offer unprecedented degrees of freedom to create on-demand material properties that cannot be attained by the constituents alone. Among a plethora of peculiar properties, we employ SNOM to image polaritonic waves —— collective hybrid light-matter modes ——including plasmon polaritons in graphene, phonon polaritons in h-BN thin layers and exciton polaritons in TMDC. 

Single defects in low-dimensional materials (低维材料单缺陷): Defects are ubiquitous in natural crystalline solids and can also be artifically created, which are known to greatly impact their electronic, optical and thermal properties. Many defects can severely impede the transport of electrons or phonons. Some other single defects harbor peculiar quantum properties that make them potentially useful for quantum technologies. We are particularly interested in characterizing and manipulating single defects in carbon nanotubes and h-BN thin layers and exploring their applications in quantum nanophotonics. 

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