Initial Nonlinear Optical Characterization of 2D Layered Materials: Second Harmonic Generation of Monolayer Dichalcogenides

Author(s):

Frank C. De Lucia Jr. and Nhan C. Dang

Abstract:

We have measured the nonlinear optical (NLO) responses of 2D layered materials, focusing on second harmonic generation (SHG). Femtosecond laser pulses produced SHG from monolayers of molybdenum disulfide (MoS2) and tungsten disulfide (WS₂). Both monolayers exhibited strong SHG signals at all four excitation wavelengths tested: 800, 1200, 1300, and 1400 nm. We also observed the expected quadratic relationship between SHG spectrum intensity and laser power. WS2 produced a stronger SHG signal from 800-nm excitation, whereas SHG from MoS2 was stronger among 1200, 1300, and 1400 nm. This initial work provides the foundation for further NLO studies including third harmonic generation, polarization/lattice orientation, and optical susceptibility calculations.