Light confining effect in a zero-index waveguide with unenclosed sidewalls and a design scheme of a reflectionless...

In our work, we have demonstrated an interesting effect: the light confining effect in an epsilon-mu-near-zero (EMNZ) waveguide with unenclosed sidewalls. The EMNZ waveguide can have perfect transmittance even though the sidewalls are unenclosed. All of the light propagating in the EMNZ waveguide is confined to the EMNZ when the connection of each sidewall is not broken. We also demonstrate that even though most of the surfaces of EMNZ are exposed to air rather than covered by perfect electric conductor or perfect magnetic conductor side walls, it is still possible for the EMNZ waveguide to exhibit the light confining effect, which is quite different from a conventional waveguide. The light confining effect of the EMNZ waveguide has rarely been discussed in previous works. Based on the light confining effect, we propose a new design scheme of a reflectionless polarization converter without using an optical active medium or structures. Our proposal provides the possibility of the application of zero-index metamaterials in the field of modulation of optical polarization.