WSe2 Nanodots on Dielectric Nanopillars for Efficient Waveguide Coupling of Localized Emitters

초록

Quantum emitters in two-dimensional transition-metal dichalcogenide (TMD) monolayers are promising candidates for on-chip quantum light sources in photonic integrated circuits, owing to their strong light-matter interactions and ease of integration. While these emitters can be coupled to waveguides via simple monolayer transfer, the coupling efficiency of this approach is fundamentally limited by the mismatch between the dipolar radiation field and the waveguide mode. Here, we propose a nanopillar-based coupling scheme that significantly enhances the coupling efficiency of atomically thin localized emitters. We fabricate TMD monolayer nanodots on dielectric nanopillars, which can then be picked and placed onto a target substrate. By subsequently encapsulating the nanopillar within a waveguide, the emitter can be incorporated into the waveguide core with its dipole orientation aligned perpendicular to the propagation direction. Finite-difference time-domain simulations reveal that this nanopillar-based scheme enables a pronounced enhancement in coupling efficiency, 3-fold higher than that of direct transfer. As a proof-of-concept experimental demonstration, we successfully fabricate WSe2 monolayer nanodots on dielectric nanopillars and observe localized photoluminescence. While the current study focuses on the material-level demonstration and model verification, our results establish a robust design framework for high-efficiency, large-scale integration of two-dimensional quantum light sources into waveguides.

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