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We investigate inverse-rib plasmonic waveguides with subwavelength confinement in the case of a first normal waveguide with losses coupled to a second one with nearly-balanced added gain. We find a smoothed version of the expected PT-symmetry breaking behavior but propose a way to restore its sharpness, and therefore to restore very high differential gain of the system.

plasmonics; waveguides; gain ;PT-symmetry; singularity