A method for removing echoes in the terahertz time-domain spectroscopy system

Terahertz spectrum is usually obtained by the terahertz time-domain spectroscopy technique. The spectral resolution is limited by the reflections of terahertz pulses from GaAs substrate and ZnTe crystal which cause echoes in the time domain and oscillations in the frequency domain. This paper proposed a de-convolution algorithm to remove these echoes. In our method, the nonlinear absorption effect of the material is considered. The absorption and group delay effect of THz pulses are analyzed through an adaptive algorithm which eliminates the oscillations effectively and recovers the original waveform without the inference of reflections. The spectral resolution is improved from 40GHz to 20GHz after processing. The algorithm has good adaptability and can be applied to large-scale data processing in terahertz time-domain spectroscopy systems.