  Epsilon-near-zero materials are exceptional candidates for studying
electrodynamics and nonlinear optical processes at the nanoscale. We
demonstrate that by alternating a metal and a highly doped conducting-oxide,
the epsilon-near-zero regime may be accessed resulting in an anisotropic,
composite nanostructure that significantly enhances nonlinear interactions.
Using two independent and different computation techniques we show that the
structure can enhance the local field intensity by nearly two orders of
magnitudes, in large part due to the onset of the effective anisotropy. The
investigation of the multilayer nanostructure using a microscopic, hydrodynamic
approach also sheds light on the roles of two competing contributions that are
for the most part overlooked, but that can significantly modify linear and
nonlinear responses of the structure: nonlocal effects, which blueshift the
resulting resonance, and the hot electron nonlinearity, which redshifts the
plasma frequency as the effective mass of free electrons increases as a
function of incident power density. Finally, we show that, even in absence of
second order bulk nonlinearity, second order nonlinear processes are also
significantly enhanced by the layered structure.
