Control of Fano asymmetry in plasmon induced transparency and its application to plasmonic waveguide modulator

In this paperwe derive a governing equation for spectral asymmetry in electromagnetically induced transparency (EIT). From the key parameters of asymmetry factor - namely dark mode quality factor Qd, and frequency separation between bright and dark mode-bd = (b - d) -, a logical pathway for the maximization of EIT asymmetry is identified. By taking the plasmonic metal-insulator-metal (MIM) waveguide as a platform, a plasmon-induced transparency (PIT) structure of tunable frequency separation-bd and dark mode quality factor Qd is suggested and analyzed. Compared to previous works on MIM-based plasmon modulatorsan order of increase in the performance Fig. (12dB contrast at ∼60% throughput) was achieved from the highly asymmetricnarrowband PIT spectra.