Surface plasmon laser based on metal cavity array with two different modes

The phenomenon of surface plasmon (SP) laser based on a square array of rectangular cavities cut into a metal substrate has been investigated. Both main resonant modes of the proposed structure can be used to realize SP laser while the working mechanism is different. We study the origin of these differences and propose an efficient design that exploits them. Besides, the effect of the sample size on SPP mode lasing is also discussed.