Dielectric environment engineering via 2D material heterostructure formation on a hybrid photonic crystal nanocavity [Invited]

Hybrid integration of two-dimensional (2D) materials with nanophotonic structures has enabled compact and tunable optoelectronic devices. Yet, the influence of local dielectric perturbations introduced during integration remains underexplored, particularly for multilayer or heterostructure assemblies. Here, we demonstrate deliberate dielectric environment engineering of photonic crystal (PhC) nanocavities through sequential stacking of 2D material flakes. Building upon our previous finding that a monolayer can induce a self-aligned cavity, we show that multilayer and heterostructure stacking enable further post-fabrication control over cavity properties. The hybrid nanocavities maintain high optical quality under multiple transfers, and encapsulation with hexagonal boron nitride (hBN) yields nearly twofold recovery of the quality factor by effectively smoothing the refractive-index profile and reducing out-of-plane losses. These experimental results are consistent with numerical simulations. Enhanced photoluminescence and reduced emission lifetime from the MoTe 2 flake on the hybrid cavity confirm Purcell-enhanced light-matter coupling. These results establish a robust and reconfigurable strategy for tuning cavity performance through controlled heterostructure assembly, expanding the design toolbox for scalable hybrid nanophotonic systems.