Macroscopic transition metal dichalcogenides monolayers with uniformly high optical quality.

The unique optical properties of transition metal dichalcogenide (TMD) monolayers have attracted significant attention for both photonics applications and fundamental studies of low-dimensional systems. TMD monolayers of high optical quality, however, have been limited to micron-sized flakes produced by low-throughput and labour-intensive processes, whereas large-area films are often affected by surface defects and large inhomogeneity. Here we report a rapid and reliable method to synthesize macroscopic-scale TMD monolayers of uniform, high optical quality.

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

Two-dimensional semiconductors have emerged as a new class of materials for nanophotonics owing to their strong exciton-photon interaction and their ability to be engineered and integrated into devices. 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. Lasing is measured from a transition-metal dichalcogenide heterobilayer (WSe-MoSe) integrated in a silicon nitride grating resonator.