Optical properties of MoSe2 nanosheets: characterization, simulation and application for Q-switching

We fabricated few layer MoSe2 nanosheets via the simple and low-cost ultrasonic-assisted liquid phase exfoliation (UALPE) method. Both the Raman spectrum and the TEM topography confirmed the few-layer structure of the fabricated MoSe2 nanosheets. The modulation depth of the MoSe2 nanosheets was 10.8% and the saturation intensity was 51 kW/cm2. Using the density functional theory (DFT), we investigated the electronics and optical properties, especially the absorption spectrum. As an application, a passively Q-switched laser was realized based on the MoSe2 nanosheets as the saturable absorber. The stable pulse train was produced with an output power of 175 mW. The minimum pulse width we obtained was 217 ns while the pulse energy was 0.36 µJ.