  We have demonstrated a versatile method for fabrication of biaxial hyperbolic
metamaterials (HMMs) using layered structures consisting of titanium dioxide
and copper. In order to enable the biaxial property, an oblique angle
deposition technique is applied to deposit the dielectric layer in the form of
columnar nanostructures. We have experimentally characterized the biaxial
dispersion using variable angle spectroscopic ellipsometry measurements in the
wavelength range 400nm to 900nm. A noticeable difference between the in-plane
permittivity components is observed which has proved to be immune from
fabrication errors. A biaxial HMM fabricated according to our method provides
dual epsilon-near-zero properties at visible wavelengths which are separated
over a bandwidth of 7nm. The experimental characterization results of the
fabricated biaxial HMM have been in good agreement with the predictions of
effective medium approximation. Our proposed method may be beneficial to
accelerate the realization of new devices in nanophotonics applications.
