Application of Capacitive Microstructures as Anti-Aliasing Filters for Terahertz Time-Domain Spectroscopy

This paper first considers an approach based on the application of high-performance capacitive microstructures as anti-aliasing filters for low-frequency (sub-terahertz) measurements in terahertz time-domain spectroscopy. The approach was tested in measurements of the spectra of reference samples — bandpass filters with central frequencies of 156 and 376 GHz and a bandwidth of ∼12%. It is shown that the spectrometer measurement time is decreased by a factor of up to 12 with an improvement in measurement accuracy due to the elimination of the long-term drift of the normalization signal. This approach is supposed to be used to increase the dynamic range and the spectrometer signal-to-noise ratio in the sub-terahertz region.