  The ability to control the polarization of light at the extreme nanoscale has
long been a major scientific and technological goal for photonics. Here we
predict the phenomenon of polarization splitting through van der Waals
heterostructures of nanoscale thickness, such as graphene-hexagonal boron
nitride (hBN) heterostructures, at infrared frequencies. The underlying
mechanism is that the designed heterostructures possess an effective relative
permittivity with its in-plane (out-of-plane) component being unity (zero);
such heterostructures are transparent to the transverse-electric (TE) waves
while opaque to the transverse-magnetic (TM) waves, without resorting to the
interference effect. Moreover, the predicted phenomenon is insensitive to
incident angles. Our work thus indicates that van der Waals heterostructures
are a promising nanoscale platform for the manipulation of light, such as the
design of polarization beam nano-splitters and epsilon-near-zero materials, and
the exploration of superscattering for TM waves while zero scattering for TE
waves from deep-subwavelength nanostructures.
