First-Principles Investigation of Nonlinear Optical Properties of 2D Materials

Understanding the interaction between 2D materials and strong electromagnetic field is important for the development of novel devices for optical spectroscopy and imaging, sensors and information technology. Here we present our recent studies of nolinear optical responses in 2D materials using our in-house developed nonlinear optical response codes based on first-principles density-functional theory. We will show that nanomaterials especially 2D materials exhibit large second and third order nonlinear optical responses, including second harmonic generation, shift current, circular photogalvanic current, and third harmonic generation. Their physical origin is closely related to topological quantity of intraband and interband Berry connection as well as electron/hole group velocity. The present results demonstrate the great potential of low-dimensional materials for nonlinear optical device and sensing applications. References: 1. Giant Optical Second Harmonic Generation in Two-Dimensional Multiferroics. Nano Letters 17, 5027-5034 (2017). 2. Two-dimensional multiferroics in monolayer group IV monochalcogenides. 2D Materials 4, 015042 (2017). 3. Third Harmonic Generation in 2D Materials. in preparation (2017).