  We study the classical scattering problem of a plane electromagnetic wave
incident on the surface of semi-infinite periodic stratified media
incorporating anisotropic dielectric layers with special oblique orientation of
the anisotropy axes. We demonstrate that an obliquely incident light, upon
entering the periodic slab, gets converted into an abnormal grazing mode with
huge amplitude and zero normal component of the group velocity. This mode
cannot be represented as a superposition of extended and evanescent
contributions. Instead, it is related to a general (non-Bloch) Floquet
eigenmode with the amplitude diverging linearly with the distance from the slab
boundary. Remarkably, the slab reflectivity in such a situation can be very
low, which means an almost 100% conversion of the incident light into the
axially frozen mode with the electromagnetic energy density exceeding that of
the incident wave by several orders of magnitude. The effect can be realized at
any desirable frequency, including optical and UV frequency range. The only
essential physical requirement is the presence of dielectric layers with proper
oblique orientation of the anisotropy axes. Some practical aspects of this
phenomenon are considered.
