Calibration Technique for THz Time-Domain Spectrometers Enabling Vectorial Scattering Parameter Measurements

To date, the most proficient instrument type for rapid measurements of broadband terahertz (THz) spectra is the time-domain spectrometer, which acquires the RF signal either transmitted through or reflected by a sample without following a standardized method for calibration. Simultaneously, application-oriented research drives a strong need for fast and precise instrumentation capable of capturing well-established characteristics, such as scattering parameters. In this letter, a robust THz instrument capable of synchronously measuring transmission and reflection from 150 GHz to 3 THz is implemented and evaluated. The main sources of error in the system are characterized, and an adapted network analysis calibration scheme for magnitude- and phase-correct wideband scattering parameter measurements is proposed. Finally, the method is validated in a comparison of simulation and measurement of a known sample.

Automated summary

The most proficient instrument for rapid measurements of broadband terahertz spectra is the time-domain spectrometer, driven by a strong need for fast and precise instrumentation in application-oriented research. This study proposes an adapted network analysis calibration scheme for magnitude- and phase-correct wideband scattering parameter measurements, validated through a comparison of simulation and measurement results.