Phase-sensitive time-domain terahertz reflection spectroscopy

An approach to time-domain terahertz reflection spectroscopy is proposed and demonstrated. It allows one to obtain very accurately the relative phase of a reflected THz wave form, and consequently the complex dielectric function can be precisely extracted. The relevant setup was demonstrated to allow measurements of a variety of samples: we present results for doped silicon and for ferroelectric ${\mathrm{SrBi}}_2{\mathrm{Ta}}_2{\mathrm{O}}_9$ (bulk ceramics as well as thin film on sapphire substrates).