Phase Delay of Terahertz Fabry-Perot Resonator characterized by a Photonic Two-Tone Spectroscopy System with Self-Heterodyne Receiver

Terahertz phase delay of high-resistive Silicon based Fabry-Perot resonators (FPR) is experimentally investigated using a photonic two-tone THz spectroscopy system with a self-heterodyne receiver. The photonic spectroscopy system consists of two free-running lasers of which one is externally modulated and an InP-based photodiode for two-tone THz signal generation. A Schottky barrier diode (SBD) is employed as self-heterodyne THz receiver. This way, spectroscopic THz phase and amplitude characterization is enabled without bulky delay lines and the phase noise of the two free running lasers is canceled out. By employing the developed photonic spectroscopy system, phase delay and transmission of a THz FPR is experimentally characterized between 270 GHz and 305 GHz. It is furthermore shown, that the measured THz phase delay difference and FSR of 23 degrees and 13 GHz, respectively, as well as the measured THz transmission coefficient agree well with an analytic model for the phase delay of a Fabry-Perot resonator.