Electromagnetically induced transparency of double-groove shaped plasmonic waveguide

The plasmonic waveguide with double-groove shaped metal–insulator–metal (MIM) structure is proposed in theory. For symmetrical double-groove, it is found that the transmission varies with the increase of the groove depth, which can be interpreted by transmission line theory. This subwavelength-scale structure exhibits the filter characteristic due to the destructive interference of the SPP modes. For unsymmetrical double-groove, this plasmonic waveguide exhibits electromagnetically induced transparency window. The work wavelength is chosen in this window, and the subwavelength slow-light mode is obtained. A small group velocity (c/80) can be achieved. Finite difference time-domain (FDTD) method is conducted to verify our design.