Free-space time domain THz spectroscopy accesses material electrodynamic responses in a frequency regime ideally matched to interacting condensed matter energy scales. THz spectroscopy, however, is challenging when samples are physically smaller than the diffraction limit of ~0.5 mm, as is typical, for example, in van der Waals materials and heterostructures. We examine engineering considerations at THz frequencies, present an on-chip, time-domain THz spectrometer with a bandwidth of 750 GHz, and extract the optical conductivity of a 7.5-um wide NbN film across the superconducting transition. Our spectrometer’s interchangeable sample architecture makes it ideal for probing superconductivity, magnetism, and charge order in strongly correlated van der Waals materials.
Engineering an on-chip THz time domain spectrometer for van der Waals materials
Host: Sergio de la Barrera