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.