  Integration of the next generation of photonic structures with electronic and
optical on-chip components requires the development of effective methods for
confining and controlling light in subwavelength volumes. Several techniques
enabling light coupling to sub-wavelength objects have recently been proposed,
including grating-, and composite-based solutions. However, experi-mental
realization of these couplers involves complex fabrication with \sim 10nm
resolution in three dimensions. One promising alternative to complex coupling
structures involves materials with vanishingly small dielectric permittivity,
also known as epsilon-near-zero (ENZ) materials. In contrast to the previously
referenced approaches, a single at layer of ENZ-material is expected to provide
effcient coupling between free-space radiation and sub-wavelength guiding
structures. Here we report the first direct observation of bulk-ENZ-enhanced
transmission through a subwavelength slit, accompanied by a theoretical study
of this phenomenon. Our study opens the door to multiple practical applications
of ENZ materials and ENZ-based photonic systems.
