[NCTS-Phys seminar] Excitonic nonlinear optics
Title：Excitonic nonlinear optics
Speaker：Prof. Thomas Garm Pedersen (Aalborg University, Denmark)
Date：2024/1/10 (Wed.)
Time：14:00 start
Place：4F Lecture Hall, Cosmology Hall, NTU
Abstract：
Excitonic many-body effects are known to affect linear optical properties significantly. This is particularly obvious in low-dimensional semiconductors due to increased electron-hole overlap and reduced screening. Therefore, such effects are expected to be important in nonlinear optical response as well. However, excitonic nonlinear optics is somewhat more complicated due to competing intra- and interband contributions as well as gauge issues and computational demands. I this talk, I will present some of our recent work on nonlinear optical properties of two-dimensional materials. At the free-carrier level, we have identified promising 2D materials for second-order nonlinear optical applications including shift-current photovoltaics. I will then go on to our recent attempts at including excitonic effects. Gauge-invariance and selection rules will be discussed. Finally, examples covering transition-metal dichalcogenides and buckled monolayers will be presented.
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