Efficient All-Optical Plasmonic Modulators with Atomically Thin Van Der Waals Heterostructures.

Guo, Xiangdong; Liu, Ruina; Hu, Debo; Hu, Hai; Wei, Zheng; Wang, Rui; Dai, Yunyun; Cheng, Yang et al. · Adv Mater · 2020

basic_science · Level V

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Abstract

All-optical modulators are attracting significant attention due to their intrinsic perspective on high-speed, low-loss, and broadband performance, which are promising to replace their electrical counterparts for future information communication technology. However, high-power consumption and large footprint remain obstacles for the prevailing nonlinear optical methods due to the weak photon-photon interaction. Here, efficient all-optical mid-infrared plasmonic waveguide and free-space modulators in atomically thin graphene-MoS<sub>2</sub> heterostructures based on the ultrafast and efficient doping of graphene with the photogenerated carrier in the monolayer MoS<sub>2</sub> are reported. Plasmonic modulation of 44 cm<sup>-1</sup> is demonstrated by an LED with light intensity down to 0.15 mW cm<sup>-2</sup> , which is four orders of magnitude smaller than the prevailing graphene nonlinear all-optical modulators (≈10<sup>3</sup> mW cm<sup>-2</sup> ). The ultrafast carrier transfer and recombination time of photogenerated carriers in the heterostructure may achieve ultrafast modulation of the graphene plasmon. The demonstration of the efficient all-optical mid-infrared plasmonic modulators, with chip-scale integrability and deep-sub wavelength light field confinement derived from the van der Waals heterostructures, may be an important step toward on-chip all-optical devices.