Orthogonally Polarized Excitons Under Quasi-One-Dimensional Moiré Confinement

Moiré superlattices in two-dimensional (2D) transition metal dichalcogenides (TMDs) offer a versatile platform to engineer excitonic states through interlayer coupling and symmetry control. While twist-induced 2D moiré superlattices have been widely investigated, excitonic responses in anisotropic moiré potentials remain much less explored, particularly in homobilayer systems. Here, we investigate exciton properties and optical responses in a WSe₂ homobilayer where uniaxial strain is applied to one monolayer while the other remains essentially unstrained, thereby forming a heterostrained bilayer with a quasi-one-dimensional (quasi-1D) moiré potential. The resulting anisotropic moiré landscape supports both interlayer and intralayer excitons whose optical responses are strongly shaped by symmetry breaking. Polarization-resolved spectroscopy reveals that intralayer exciton emission is linearly polarized along the heterostrain-defined principal axis of the quasi-1D moiré potential, whereas interlayer emission is polarized along the orthogonal axis. We further find that interlayer excitons exhibit predominantly out-of-plane transition-dipole character, whereas intralayer excitons possess in-plane dipoles, resulting in distinct polarization anisotropies dictated by symmetry. Their coexistence within the same anisotropic moiré environment enables polarization-selective and direction-dependent modulation of excitonic states, in stark contrast to conventional isotropic moiré systems. This work establishes heterostrain-engineered moiré homobilayers as a platform for anisotropic excitonic physics and deterministic control of exciton polarization.