Interlayer exciton laser of extended spatial coherence in atomically thin heterostructures.

Paik, Eunice Y; Zhang, Long; Burg, G William; Gogna, Rahul; Tutuc, Emanuel; Deng, Hui · Nature · 2019

basic_science · Level V

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Abstract

Two-dimensional semiconductors have emerged as a new class of materials for nanophotonics owing to their strong exciton-photon interaction<sup>1,2</sup> and their ability to be engineered and integrated into devices<sup>3</sup>. Here we take advantage of these properties to engineer an efficient lasing medium based on direct-bandgap interlayer excitons in rotationally aligned atomically thin heterostructures<sup>4</sup>. Lasing is measured from a transition-metal dichalcogenide heterobilayer (WSe<sub>2</sub>-MoSe<sub>2</sub>) integrated in a silicon nitride grating resonator. An abrupt increase in the spatial coherence of the emission is observed across the lasing threshold. The work establishes interlayer excitons in two-dimensional heterostructures as a gain medium with spatially coherent lasing emission and potential for heterogeneous integration. With electrically tunable exciton-photon interaction strengths<sup>5</sup> and long-range dipolar interactions, these interlayer excitons are promising for application as low-power, ultrafast lasers and modulators and for the study of many-body quantum phenomena<sup>6</sup>.