Optical Signatures of Interfacial Coupling in van der Waals Superconductor–Semiconductor Heterostructures

Hybrid interfaces between high-Tc superconductors and atomically thin semiconductors offer a new avenue to study interfacial quantum coupling and proximity effects in two-dimensional systems. Yet, assembling layered cuprates within van der Waals stacks has remained difficult due to their sensitivity to temperature and atmosphere during transfer. We developed a cryogenic stacking method operating at liquid-nitrogen temperature, enabling the integration of pristine superconducting oxides with 2D semiconductors. Temperature-dependent photoluminescence and differential reflectance measurements reveal reproducible optical anomalies emerging near the superconducting transition of the underlying cuprate, pointing to a modification of the interfacial dielectric response. These findings suggest that the superconducting condensate influences the excitonic environment across the hybrid interface, opening a route to probe correlated quantum phases optically in van der Waals superconductor–semiconductor systems.