In a single nanoscale device,surface plasmon polaritons (SPPs) have potential to match the different length scales associated with photonics and electronics.In this Letter,we propose an accurate design of a plasmonic metasurface Luneburg lens (PMLL) accommodating SPPs.The simulations indicate that the full width at half-maximum is 0.42 μm,and the focus efficiency is 78％.The characters of a PMLL have robustness to manufacturing errors.The PMLL is applied in a 10 μm long compact coupler model,which couples the SPPs to the 40 nm wide output waveguide.The couple efficiency is higher than that of a conventional taper coupler in a broad bandwidth.The design is compatible with standard lithography technology.