Excitonic emission of monolayer semiconductors near-field coupled to high-Q microresonators

TL;DR

This paper demonstrates near-field coupling of monolayer WSe2 to high-Q microresonators, enabling precise quantum yield measurements and insights into excitonic emission dynamics in layered materials.

Contribution

It introduces an efficient near-field coupling scheme with tapered fibers for high-Q microresonators, preserving quality factors and enabling detailed excitonic emission analysis.

Findings

Cavity quantum yield is approximately 10^-3.

Coupling preserves high intrinsic quality factor ($Q>10^6$).

Emission lifetime is shorter than cavity decay time, indicating broad emitter regime.

Abstract

We present quantum yield measurements of single layer $\textrm{WSe}_2$ (1L-$\textrm{WSe}_2$) integrated with high-Q ($Q>10^6$) optical microdisk cavities, using an efficient ($\eta>$90%) near-field coupling scheme based on a tapered optical fiber. Coupling of the excitonic emission is achieved by placing 1L-WSe$_2$ to the evanescent cavity field. This preserves the microresonator high intrinsic quality factor ($Q>10^6$) below the bandgap of 1L-WSe$_2$. The nonlinear excitation power dependence of the cavity quantum yield is in agreement with an exciton-exciton annihilation model. The cavity quantum yield is $\textrm{QY}_\textrm{c}\sim10^{-3}$, consistent with operation in the \textit{broad emitter} regime (i.e. the emission lifetime of 1L-WSe$_2$ 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.