[PAST EVENT] Physics Colloquium - Guangxin Ni
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Guangxin Ni, Columbia University, Title of talk: Nano-light in van der Waals heterostructures
Abstract: Near-field nano-optics as a new and vibrant area of research has enabled the control and manipulation of electromagnetic radiations at the nano-meter length scales. In this talk, Dr. Ni will discuss recent nano-optical experiments on two-dimensional graphene/hexagonal boron nitride (G/hBN) van der Waals heterostructures. By harnessing infrared nano-optics one can directly image surface plasmon polaritonic standing waves and uncover its fundamental limits of graphene plasmonics [Nature (2018)]. The presence of periodic moir? patterns enables further fine tuning of the host materials and yielding rich insights into the electronic phenomenons. This has been manifested in both G/hBN moir? patterns [Nature Materials (2015)] and twisted bilayer graphene moir? structures [Science (2018)]. Furthermore, by examining the sub picosecond dynamics of plasmons in a unique set of pump-probe spectroscopy apparatus we were able to switch on plasmon on demand [Nature Photonics (2016)].