Lasing of Moiré Trapped MoSe${}_2$/WSe${}_2$ Interlayer Excitons Coupled to a Nanocavity

We report lasing of moiré trapped interlayer excitons (IXs) by integrating a pristine hBN-encapsulated MoSe${}_2$/WSe${}_2$ heterobilayer into a high-$Q$ ($>{10}^4$) nanophotonic cavity. We control the cavity-IX detuning using a magnetic field and measure their dipolar coupling strength to be $78\pm 4\mu \mathrm{e}\mathrm{V}$, fully consistent with the 82 $\mu \mathrm{e}\mathrm{V}$ predicted by theory. The emission from the cavity mode shows clear threshold-like behavior as the transition is tuned into resonance with the cavity. We observe a superlinear power dependence accompanied by a narrowing of the linewidth as the distinct features of lasing. The onset and prominence of these threshold-like behaviors are pronounced at resonance while weak off-resonance. Our results show that a lasing transition can be induced in interacting moiré IXs with macroscopic coherence extending over the length scale of the cavity mode. Such systems raise interesting perspectives for low-power switching and synaptic nanophotonic devices using two-dimensional materials.