Rapid multiplex ultrafast nonlinear microscopy for material characterization

TL;DR

This paper introduces a rapid, nonlinear microscopy technique based on four-wave mixing for real-time, in-situ characterization of advanced materials, providing more detailed insights than traditional methods.

Contribution

The authors develop and demonstrate a fast, ultrafast nonlinear imaging method using four-wave mixing to assess material quality through nonlinear response measurements.

Findings

FWM-based imaging accurately measures exciton dephasing and lifetimes.

Compared to traditional techniques, FWM provides more detailed material quality assessment.

Ultrafast FWM imaging is feasible at room temperature for real-time analysis.

Abstract

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 WSe$_2$ 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.