Time-domain dielectric constant measurement of thin film in GHz–THz frequency range near the Brewster angle

We present a free-space time-domain method to measure the dielectric property of thin film on substrate in the GHz–THz frequency range. The concept is based on the phase flip of the field wave form for near-Brewster angle reflection. Realizing this concept, we demonstrate the determination of the dielectric constant of a thin polymer film at a few micrometer thickness on the silicon wafer.