Loss compensation symmetry in dimers made of gain and lossy nanoparticles

The eigenoscillations in a two-dimensional dimer made of gain and lossy nanoparticles were investigated within exact analytical approach. It was shown that there are eigenoscillations for which all Joule losses are exactly compensated by the gain. Among such solutions, there are solutions with a new type of symmetry, which we refer to as Loss Compensation Symmetry (LCS) as well as well-known PT (parity-time) symmetric solutions. The modes with LCS unlike PT symmetric ones allow one to achieve full loss compensation with significantly less gain that in the case of PT symmetry. This effect paves way to the new loss compensation methods in optics.