Measurement of dielectric constant and loss tangent of several common dielectrics by terahertz time domain spectroscopy

Conventional coherent and non-coherent techniques such as quasi-optical vector network analyze (VNA) and Fourier transform spectroscopy (FTS) can be employed to measure the exhaustive properties of dielectrics in the terahertz band. However, the VNA can only cover a narrow frequency range, and the FTS takes a relatively long period of time for measurement. By contrast, the terahertz time domain spectroscopy (TDS) allows the measurement of material properties such as dielectric constant and loss tangent in a wide frequency range and in a short period of time. Using a terahertz TDS, we characterize the complex properties of some materials commonly used in terahertz superconducting receivers, including high density polyethylene (HDPE), single crystal magnesium oxide (MgO), single crystal quartz, single crystal sapphire, single crystal silicon (S.C. silicon), high resistance silicon (H.R. silicon), and ultra-high molecular weight polyethylene (UHMWPE). The measurements at room temperature have finished yet. The measurements at cryostat temperature are in progress and will be published later.