Total transmission through a sub-wavelength slit based on Fabry–Pérot resonance and zero-index metamaterials

In this work, we theoretically investigate the transmission effect of electromagnetic wave in a waveguide structure with a dielectric slit of a sub-wavelength width, on both sides of which zero index metamaterials (ZIMs) are placed. We show that the transmittance in such a waveguide structure can increase considerably due to the squeezing function of ZIMs. In particular, total transmission can be achieved when the Fabry–Pérot resonance condition is satisfied by adjusting the material properties of the dielectric filled in the slit. Numerical simulations agree well with analytic results. Because the media filled in the sub-wavelength slit are not necessarily ZIMs but just normal dielectrics, our work greatly reduces the difficulty for implementation.