Terahertz Reflection Spectroscopy*

The study of light-matter interactions is key in providing fundamental information about the physics of artificial materials. The spectroscopic response of a material encodes properties of the ground state as well as of its excitations. This has been critical in the understanding of novel quantum materials; the further improvement of spectroscopic techniques will continue to be key in the exploration of novel states of matter. We have developed a setup for time-domain Terahertz (THz) reflection spectroscopy to complement the more traditional transmission experiments. The advantages of reflection are that it expands the measurement capabilities to metallic samples, it can distinguish between electric and magnetic-dipole excitations, and it can help determine the full THz optical tensor.