We report collective dark states controlled transmission inmetal-dielectric-metal waveguides with a stub coupled to two twin cavities,namely, plasmonic waveguide-stub-dimer systems. In absence of one individualcavity in the dimer, plasmon induced transparency (PIT) is possible when thecavity and the stub have the same resonance frequency. However, it is shownthat the hybridized modes in the dimer collectively generate two dark stateswhich make the stub-dimer "invisible" to the straight waveguide, splitting theoriginal PIT peak into two in the transmission spectrum. Simultaneously, theoriginal PIT peak becomes a dip due to dark state interaction, yieldinganti-PIT-like modulation of the transmission. With full-wave electromagneticsimulation, we demonstrate that this transition is controlled by the dimer-stubseparation and the dimer-stub relative position. All results are analyticallydescribed by the temporal coupled mode theory. Our results may be useful indesigning densely integrated optical circuits, and in optical sensing andswitching applications.
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