Fig. 2: Illustration of the time-dependent detector signal of a FMCW THz spectrometer with stepwise frequency tuning. | Nature Communications

Fig. 2: Illustration of the time-dependent detector signal of a FMCW THz spectrometer with stepwise frequency tuning.

From: Optoelectronic frequency-modulated continuous-wave terahertz spectroscopy with 4 THz bandwidth

Fig. 2: Illustration of the time-dependent detector signal of a FMCW THz spectrometer with stepwise frequency tuning.The alternative text for this image may have been generated using AI.

a Frequency of the incident THz field ETHz,Rx and the optical beat note IB,Rx at the receiver as a function of time. The time delay T between ETHz,Rx and IB,Rx, the frequency step size Δf and the cycle time τs are indicated. b Time-dependent frequency and c phase of the electrical signal after photomixing in the receiver. Frequency and phase of the receiver signal change by Δf and Δϕ, respectively, within the time T. The quantity f0 denotes the linearized intermediate frequency, which is used for signal detection in our realization of the FMCW THz spectrometer.

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