Tunable WS$_2$ Micro-Dome Open Cavity Single Photon Source

TL;DR

The paper addresses the need for compact, tunable, scalable single-photon sources for quantum technologies, particularly leveraging atomically thin TMDC emitters. It demonstrates a cavity-tunable single-photon source based on hydrogen-irradiated $WS_{2}$ micro-domes integrated into an open Fabry–Pérot cavity, enabling deterministic emitter–cavity alignment. A spectrally selective emitter–cavity coupling model that accounts for phonon degrees of freedom explains the observed phonon-sideband contributions and the asymmetric detuning behavior. Key results include up to a factor of $17.0$ cavity enhancement at zero detuning and a measured $g^{(2)}(0) = 0.27 \\pm 0.08$, with a lifetime of $\\tau_1 = 1.954 \\pm 0.024 \\mathrm{ns}$, confirming high-purity single-photon emission. The work shows that open-cavity platforms can tailor emission from 2D materials and points toward scalable, spectrally selective TMDC-based quantum light sources for networks and quantum optomechanics.

Abstract

Versatile, tunable, and potentially scalable single-photon sources are a key asset in emergent photonic quantum technologies. In this work, a single-photon source based on WS$_2$ micro-domes, created via hydrogen ion irradiation, is realized and integrated into an open, tunable optical microcavity. Single-photon emission from the coupled emitter-cavity system is verified via the second-order correlation measurement, revealing a $g^{(2)}(τ=0)$ value of 0.3. A detailed analysis of the spectrally selective, cavity enhanced emission features shows the impact of a pronounced acoustic phonon emission sideband, which contributes specifically to the non-resonant emitter-cavity coupling in this system. The achieved level of cavity-emitter control highlights the potential of open-cavity systems to tailor the emission properties of atomically thin quantum emitters, advancing their suitability for real-world quantum technology applications.

Figures (3)

• Figure 1: (a) To-scale schematic of the $\sim$5µ m long open cavity containing the hydrogenated and hBN-capped WS2 layer. The topography of the active layer is scaled by a factor of 10.0 in the $z$ direction. (b) AFM measurement of the hBN-capped, hydrogenated WS2 layer. The edges of the WS2 layer are indicated by a dashed green line, one of the edges of the hBN layer on top of it is shown by the dashed blue line, and the part shown in (a) is indicated by a dashed white square. An inset at the bottom right shows a dome before it was capped with hBN. It is scaled by a factor of 1.5 compared to (a). (c) PL map matching the region shown in (b), displaying the spectrally integrated intensity in the 622.0--650nm range under 532nm continuous wave laser excitation.
• Figure 2: (a) PL spectra for various detunings between cavity resonance energy and emitter energy, denoted as X, at approximately 1.962eV. The diagonal features correspond to the spectrally tunable cavity modes, labeled C1--C3. On resonance (zero detuning), the intensity is enhanced by approximately a factor of 17.0. (b) Second-order correlation measurement at zero detuning, yielding $g^{(2)}(0)=0.27\pm0.08$. The inset shows a lifetime measurement of the coupled system.
• Figure 3: (a) Measured PL spectra for three cavity emitter detunings with the fitted model, as well as its individual constituents, namely, the cavity and the lower (higher) energy emission feature "ZPL+PSB 1" ("ZPL+PSB 2"). (b) Integrated intensities attributed to the three modeled components (top) and the cavity emitter coupling factors (bottom) as a function of the cavity emitter detuning. The vertical thin dashed lines correspond to the three spectra shown in (a).