Excitonic Emission of Monolayer Semiconductors Near-Field Coupled to High-Q Microresonators

Abstract

We present quantum yield measurements of single layer WSe₂ (1L-WSe₂) integrated with high-Q ( Q > 10⁶) optical microdisk cavities, using an efficient (η > 90%) near-field coupling scheme based on a tapered optical fiber. Coupling of the excitonic emission is achieved by placing 1L-WSe₂ in the evanescent cavity field. This preserves the microresonator high intrinsic quality factor ( Q > 10⁶) below the bandgap of 1L-WSe₂. The cavity quantum yield is QY_c ≈ 10^-3, consistent with operation in the broad emitter regime (i.e., the emission lifetime of 1L-WSe₂ is significantly shorter than the bare cavity decay time). This scheme can serve as a precise measurement tool for the excitonic emission of layered materials into cavity modes, for both in plane and out of plane excitation.