Characterization and control of signal distortion in chirped pulse single-shot terahertz detection

We analyze distortion in chirped-pulse-based single-shot THz measurements utilizing spectral encoding, which imposes a trade-off between the measurement window (Tc) and usable bandwidth (Δω). Capturing more THz data in the time domain limits spectral content in the frequency domain, acting as a virtual low-pass filter. We categorize distortion into temporal-Fraunhofer and temporal-Fresnel regimes, analogous to spatial diffraction, defined by the characteristic dispersion length and distortion factor (β). Our framework unifies existing time- and frequency-domain THz measurement techniques with various detection instruments across different dispersion levels and β. We also extend the framework to a variety of realistic experimental THz pulse shapes and validate cutoff frequencies through experiments, demonstrate that tuning β controls distortion, and achieve a ∼2.5× increase in β with a ∼6× increase in Tc. Finally, we mitigate distortion in the Fraunhofer regime by reducing β from 1.1 to 0.8 while expanding Δω from 1.5 to 2.3 THz.