In this paper,an improved hybrid surface plasmon nanolaser with a gain medium ridge and a layer of air gap is proposed.In order to achieve low propagation loss and sub-wavelength field confinement,a triangular air gap and a 50 nm microcavity end face silver mirror are adopted in this structure,and the combination of this particular triangular structure and silver mirror effectively improves the performance of nano-laser.In this paper,we numerically simulate the waveguide by using the finite-element method.T...