A direct method to calculate second-order two-dimensional terahertz spectroscopy in frequency-domain based on classical theory

摘要： Previous theoretical researches on the two-dimensional terahertz spectroscopy (2DTS), which are conducted via inef?ciently time-consuming numerical simulation, deal with only single-mode system. To overcome the limitations, we derive a classical-theory-based analytical solution which is applicable to multi-modes system. Three typical weak sources of nonlinearities are introduced. The ?ndings suggest that the analytical results correspond well with those obtained by the traditional numerical simulation. Thus the study provides a more ef?cient and practical method to directly calculate 2DTS, and, in a broader sense, sheds new light on the theory of 2DTS.