Experimental verification of epsilon-near-zero metamaterial coupling and energy squeezing using a microwave waveguide

Utilizing a microwave setup, we experimentally verify our recently developed theory of energy squeezing and tunneling [Phys. Rev. Lett. 97, 157403 (2006)] through an ultranarrow waveguide channel that mimics zero-permittivity properties. Exploiting the infinite phase velocity supported by a waveguide transition section at cutoff, we test our theory of tunneling in this zero-permittivity region without use of resonant inclusions. This supercoupling is shown to have unique anomalous properties: an almost uniform phase along the narrow channel and weak dependence over its geometry.