3-Color Two-Beam Broadband Nonlinear Frequency Mixing: From Physics to Applications for Spectroscopy

We report the theoretical summary of 3-color two-beam broadband nonlinear frequency mixing by using the double-sided Feynman diagrams and the phenomenological picture of the light matter interactions. We measured the intensity dependence of the signal beam via excitation beams and recorded the scattering spectra that originated from molecular solutions and crystals. Pure vibrational spectra were extracted from the measured spectra with model independent phase retrieval methods. We have used our spectroscopy system published recently [1] to characterize the method. We showed that the method is extremely useful to measure molecular vibrational and vibronic spectra in the low frequency, terahertz range.

[1] Laszlo Ujj, “Contribution to the development of low frequency terahertz coherent Raman micro-
spectroscopy and microscopy “, Research article, Spectrochimica Acta Part A: Molecular and
Biomolecular Spectroscopy, Volume 199, 15, Pages 448-454.