Lasing threshold of the bound states in the continuum in the plasmonic lattices

Distributed feedback plasmonic laser based on the periodic array of holes in the silver half-space and covered with gain medium is considered. Square, hexagonal and several rectangular lattices are studied. It is demonstrated that the bound states in the continuum provide substantially lower threshold than radiating modes. Moreover, it is shown that while the hole size increases the lasing threshold of some modes decreases. Among the studied types of lattices, lasing in the hexagonal lattice requires the lowest material gain of only 18 cm^-1. Our results pave the way to the development of the efficient low-threshold distributed feedback plasmonic lasers.