Extracting accurate optical parameters from glasses usingterahertz time-domain spectroscopy

Terahertz time-domain spectroscopy (THz-TDS) can be used to characterize the optical properties of glasses in a frequency regime that is barely accessible by other techniques. It can be used to measure the electric field of a pulse of broadband terahertz radiation with frequency components between 0.1 and 4.5 THz propagating through the material of interest. Data processing is required to transform the information from the raw time-domain waveform data into the absorption spectrum. While most crystalline materials exhibit a number of distinct spectral features, amorphous materials show an almost featureless frequency response in the terahertz range and very accurate measurements of the absorption coefficient are required to characterize the materials. The accuracy of existing data processing techniques is limited as a result of truncating the time-domain data to remove multiple reflections of the terahertz pulse within the sample material and by neglecting scattering losses at the surface of the sample material. Using the experimental THz-TDS data of As 2 S 3 we present a new approach to extract accurate optical parameters from THz-TDS experimental data.