Fig. 3.

Experimental results. a Time domain signal of the PCA source measured with a 200 μm ZnTe crystal. b Electric field amplitude of the THz pulse in time domain detected by the MZI detectors with center frequencies of 1.2 and 2.4 THz, respectively. In both cases, the initial pulse of the detected time trace is attributed to the response of the HF-THz antenna component. The following slow THz pulse originates from the response of the LF antenna component. The detected signal is the convolution of the source s(t) with the impulse response of the detector h(t). c The Fourier transform (FT) of the THz time traces for the 1.2 and 2.4 THz detector, respectively. In both cases, the dynamic range is ≥60 dB for an integration time of 20 s per point with an optical probe power of 63 nW. d Measured (solid blue lines) and approximated (dashed light blue lines) complex frequency response of the detector. The frequency response of the detector can be computed from the measured spectrum in c and the spectrum of the known source in a. e Example of a retrieved input signal (black curve) as derived from a measured time trace (green curve) using the approximated frequency response in d.