Nonlinear spectroscopy can be a very powerful measurement tool that provides a fundamental understanding of the photophysics of polariton systems by unraveling the energy transfer mechanisms through lineshape features and lifetimes of the different peak intensities. Transient absorption (TA) measurements by DelPo el al. studies non-linear effects like Rabi contraction and Virgili et al. have developed kinetic models suggesting indirect energy transfer from Upper polariton (UP) to Lower polariton (LP) via dark states. Although TA is a powerful tool, it suffers from some artifacts for interpreting polariton dynamics 2D Electronic Spectroscopy (2DES), as pioneered by David Jonas and many others, can easily overcome these challenges by resolving the system dynamics along two frequency axes. The various non-linear effects that result from collective coupling in exciton-polariton systems like Rabi contraction, motional narrowing, polaron decoupling, 2,7 coherence enhancement can be directly studied by just studying the 2D lineshapes of the diagonal and cross-diagonal peaks and how these signals fluctuate in time. Takahashi and Watanabe 2 demonstrated the effect of polaron decoupling in excitonpolaritons using tetraphenyldibenzoperiflanthene (DBP) molecules coupled to a cavity, appearing as a tilt of the slope between the GSB (ground state bleach) + SE(stimulated emission) and ESA (excited state absorpa) Electronic mail: mmondal@ur.rochester.edu b) Electronic mail: pengfei.huo@rochester.edu tion) signals in the lower polariton peak. A similar study has been done by Quenzel and coworkers, where they couple Squarine J-aggregates to gold plasmonic surfaces and observe the slope tilt in the polariton 2DES peaks. Recent 2DES measurements also demonstrate energy relaxation and energy transfer mechanisms in different types of exciton-polariton systems, including Jaggregates and carbon nanotubes . These studies also demonstrate the enhancement of exciton lifetimes and coherent energy transfer lifetimes due to the collective coupling of molecules to the cavity mode.