Time-frequency filtering applied to terahertz time-domain spectroscopy

We introduce the use of Time-Frequency (TF) filtering applied to Terahertz Time-Domain Spectroscopy (THz-TDS) data in order to extract valuable information hidden into the noise floor. The Short Time Fourier Transform (STFT) provides a spectrum analysis in time, we optimized its Gaussian window in order to analyse and filter the THz signals of substances. The formalism presented allows an efficient denoising of THz-TDS data which could prove useful during the investigation of highly absorbing samples.