Transition metal dichalcogenides (TMDs) have received considerable attention in the past decade for their optoelectronic applications in photovoltaics, lasers, and quantum information. In the monolayer limit, these materials exhibit extraordinary properties, including efficient light-matter coupling, ultrafast charge transfer, long-lived interlayer bound electron-hole pairs (excitons) which are stable at room temperature, and many-body excitonic interactions. In this talk, I will present how multi-dimensional coherent spectroscopy (MDCS) allows us to study coherent and incoherent coupling between excitons in TMD heterostructures. I will further show how the development of a novel lock-in amplifier allows us to combine MDCS with imaging and study the changes of key sample properties for quantum information applications across TMD monolayers and heterostructures. Lastly, the talk will cover how to accelerate nonlinear imaging techniques to implement them in fabrication settings with experimental results supporting the advantage of four-wave mixing-based imaging over conventional material characterization techniques.