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 MoTe2 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. Journal © 2026.

Semiconductor lead halide perovskites have attracted significant attention for various applications. Understanding the impact of material composition on optical properties is essential for optimizing device performance. Here, we performed magneto-optical spectroscopy on high-quality bulk CsPbBr3, MAPbBr3, and MAPbI3 single crystals under magnetic fields of up to 30 T. The results revealed distinctive excitonic responses to the magnetic field, with bromide-based perovskites exhibiting modest diamagnetic shifts, while MAPbI3 showed a more pronounced response, even including an emission peak with a negative diamagnetic coefficient. Analysis of the magnetic-field induced photoluminescence circular polarization revealed slow exciton spin dynamics, with comparable spin relaxation and radiative recombination times across all perovskites. Our insights enhance the understanding of the complex interactions between cationic and anionic influences, offering pathways for innovations in photovoltaics, optoelectronics, and quantum optics. (c) 2025 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license(https://creativecommons.org/licenses/by/4.0/).https://doi.org/10.1063/5.0277358

Two-dimensional (2D) materials are increasingly being adopted in hybrid photonics via integration with photonic structures, including cavities. The utility of 2D materials for dielectric environment engineering in hybrid nanophotonic devices remains largely unexplored. We demonstrate self-aligned hybrid nanocavities in which 2D material flakes are used to form cavities locally wherever they are placed along the PhC waveguide postfabrication. We successfully fabricated such hybrid nanocavities with various 2D materials on silicon PhC waveguides, obtaining Q factors as high as 4.0 × 105. Remarkably, even monolayer flakes can provide sufficient local refractive index modulation to induce high Q nanocavity formation. We have also observed cavity PL enhancement in a self-aligned MoTe2 cavity device with an enhancement factor of about 15. Our results highlight the prospect of using such 2D material-induced PhC nanocavities to realize a wide range of photonic components for hybrid integrated photonic circuits. © 2024 The Authors. Published by American Chemical Society