High-efficiency and widely tunable terahertz power divider based on multilayer graphene plasmonic waveguides

The advancement of terahertz (THz) integrated photonic circuits is critically dependent on the development of compact, dynamically reconfigurable components for signal routing and manipulation. In this work, we propose and systematically analyze a novel, to our knowledge, graphene-on-insulator plasmonic power divider designed for high-efficiency operation in the THz regime. The device’s performance is investigated through rigorous finite-difference time-domain (FDTD) simulations, exploring the impact of key parameters including the graphene chemical potential (from 0 to 0.5 eV), the number of graphene layers (1–3), and the geometric dimensions of the waveguide structure. Our analysis reveals that a strategic reduction of the central coupling waveguide’s length, combined with the implementation of a three-layer graphene structure, dramatically enhances plasmon confinement and minimizes propagation and reflection losses. The optimized configuration demonstrates a peak power transmission efficiency of 93.46% at 12.36 THz. Furthermore, the device maintains an exceptionally wide and stable operational bandwidth, with transmission exceeding 90% across an extensive frequency range from 5.1 to 25.1 THz. These results establish a clear design pathway for realizing highly efficient and actively tunable plasmonic components, paving the way for next-generation reconfigurable THz metasurfaces, switches, and complex integrated photonic systems.