Abstract: Vibration and rotation frequencies of grease molecules are near to terahertz band and they can cause resonant by interaction with THz wave, so terahertz timedomain spectroscopy (THzTDS) can rapidly and sensitively detect and identify legal and illegal cooking oils. We extract the characteristic information of THz spectrum of illegal cooking oils through comparing timedomain/frequencydomain spectra of legal oil, frying oil and illegal oil in the range of 0.3~1.6 THz and analyzing their optical parameters such as time delay, refractive index, absorption coefficient and absorption peak. This provides experimental basis and effective approach for detection and identification of illegal cooking oil.Results show that THzTDS spectroscopy can effectively distinguish legal and illegal cooking oils with spectrum characteristic and unique illegal cooking oil functional group information.

Key words: optical parameter, terahertz timedomain spectroscopy, spectroscopy, illegal cooking oil