All-optical control of ultrathin trionic waveguide

The generation of high-purity localized trions, dynamic exciton-trion interconversion, and their spatial modulation in 2D semiconductors are building blocks for realizing trion-based optoelectronic devices. Here, we present an all-optical control of the trionic conversion process and its spatial distributions in a MoS₂ monolayer, demonstrating an ultrathin trionic waveguide. We induce the nanoscale strain gradient in a 2D crystal transferred on the metal-insulator-metal (MIM) waveguide and exploit the propagating surface plasmon polariton (SPP) to localize the hot electrons. These significantly increased electrons and efficiently funneled excitons in the MIM waveguide facilitate complete exciton-to-trion conversion even under ambient conditions. Additionally, we modulate the SPP mode using adaptive wavefront shaping, enabling the all-optical control of the exciton-to-trion conversion rate and the trion distribution in a reversible manner. Our work paves the way for the development of hybrid plasmo-excitonic integrated circuits that combine efficient plasmonic transport with highly radiative excitonic emission.