Rapid multiplex ultrafast nonlinear microscopy for material characterization

We demonstrate rapid imaging based on four-wave mixing (FWM) by assessing the quality of advanced materials through measurement of their nonlinear response, exciton dephasing, and exciton lifetimes. We use a WSe2 monolayer grown by chemical vapor deposition as a canonical example to demonstrate these capabilities. By comparison, we show that extracting material parameters such as FWM intensity, dephasing times, excited state lifetimes, and distribution of dark/localized states allows for a more accurate assessment of the quality of a sample than current prevalent techniques, including white light microscopy and linear micro-reflectance spectroscopy. We further discuss future improvements of the ultrafast FWM techniques by modeling the robustness of exponential decay fits to different spacing of the sampling points. Employing ultrafast nonlinear imaging in real-time at room temperature bears the potential for rapid in-situ sample characterization of advanced materials and beyond.(c) 2022 Optica Publishing Group under the terms of the Optica Open Access Publishing Agreement

Automated summary

In this study, rapid imaging based on four-wave mixing (FWM) is demonstrated for assessing the quality of advanced materials. The nonlinear response, exciton dephasing, and exciton lifetimes are measured to evaluate the material parameters. The results show that FWM technique provides a more accurate assessment of sample quality compared to current prevalent techniques. Future improvements of the ultrafast FWM techniques are discussed, including modeling the robustness of exponential decay fits. The use of ultrafast nonlinear imaging in real-time at room temperature has the potential for rapid in-situ sample characterization of advanced materials.