Optical signature of alternating domains with out-of-plane electric polarization in twisted transition metal dichalcogenide

Twisting two-dimensional materials with a small twist angle leads to a plethora of rich physical correlated and topological phenomena. Yet another emergent example is alternating domains with out-of-plane electric polarization in twisted hexagonal boron nitride and transition metal dichalcogenides systems. In this work, we perform optical spectroscopy of twisted double bilayers of transition metal dichalcogenides and reveal rich optical response, which could be further controlled by an out-of-plane electric field from a dual gate geometry. Our results demonstrate the delicate coupling between the excitonic response and the moire electric polarization, which is further visualized through scanning probe techniques.