A time-domain terahertz spectrometer with 90 dB dynamic range

We present a time-domain terahertz spectrometer based on 1550 nm fiber laser technology and InGaAs photoconductive switches. The system features a voice-coil delay stage, which offers a high scanning speed of up to 60 traces per second. Owing to a precise reconstruction of the time axis, the system achieves a high dynamic range: a single pulse trace of 50 ps is acquired in only 44 ms, and transformed into a spectrum with a peak dynamic range of 60 dB. With 800 averages, the dynamic range increases to 90 dB and the measurement time still remains as short as 35 seconds.