New method of substance detection and identification using the substance emission frequency up-conversion in the THz frequency range

摘要

We discuss an effective method for the detection and identification of substances irradiated by a broadband THz pulse. The pulse induces high energy level excitation of molecules due to essential non-stationary medium response. This leads to the substance emission at frequencies, which are absent in the incident pulse spectrum. A radiation at these frequencies possesses much penetration force through disordered structures which are usually covered a substance under detection. We propose to use the up-conversion of THz frequencies for the detection and identification of substances. Because of strong dependence of frequency conversion efficiency on its spectral intensity, the frequencies, at which THz pulse energy absorption occurs, are converted with less efficiency in comparison with conversion efficiency of those frequencies.