Enhancing the Ultrafast Third-Order Nonlinear Optical Response by Charge Transfer in VSe₂-Reduced Graphene Oxide Hybrid

Abstract

Nonlinear optical phenomena play a pivotal role in elucidating microscopic light–matter interactions and hold significant potential across diverse fields, including biosensing, quantum information, optical switching, and all-optical data processing. Realizing practical applications often demands materials exhibiting high third-order absorptive and refractive optical nonlinearities, but most materials show weak nonlinear responses due to their perturbative nature. Overcoming this limitation, charge-coupled donor–acceptor material pairs emerge as promising candidates with thriving application prospects. Here, we demonstrate that the charge-coupled donor–acceptor VSe 2 -reduced graphene oxide (rGO) hybrid exhibits enhanced ultrafast third-order absorptive and refractive nonlinearities compared to the pristine systems, at least by 1 order of magnitude. Our investigations, supported by density functional theory and Bader charge analysis, reveal robust electronic coupling within the VSe 2 –rGO hybrid, featuring efficient electron transfer from VSe 2 to rGO. Steady-state and time-resolved photoluminescence measurements provide further confirmation of the electronic coupling and charge transfer dynamics. Furthermore, we fabricate an ultrafast optical limiter device with better performance parameters, such as an onset threshold of 2.5 mJ cm –2 and a differential transmittance of 0.42.