Nonlinear Ultrafast Excitation and Two-Dimensional Terahertz Spectroscopy of Solids

• Main Author: Knighton, Brittany E.
• Format: Others
• Published: BYU ScholarsArchive 2021
• Subjects: ultrafast spectroscopy; nonlinear phononics; trilinear coupling; terahertz; ultrafast; 2D terahertz spectroscopy; Physical Sciences and Mathematics
• Online Access: https://scholarsarchive.byu.edu/etd/9190; https://scholarsarchive.byu.edu/cgi/viewcontent.cgi?article=10199&context=etd

Ultrafast spectroscopy allows us to probe and understand material properties. With it, we can measure phonon-polaritons (optical phonons coupled with light) and the resulting dispersion curve in lithium niobate. Customizing the excitation source in ultrafast measurements can excite phonon modes to large amplitudes, allowing the experimental exploration of the Potential Energy Surface in solids. However, stronger pump fluences and bigger signal isn't always the answer in ultrafast spectroscopy. When sample signals and their nonlinear and mechanisms cannot be distinguished with 1D measurements, simple 2D THz measurements are a great place to start searching for distinct factors as was the case in cadmium tungstate. 2D measurements when paired with modeling and first principles calculations can reveal cutting edge information about exciting materials.