  Propagation features of circularly polarized (CP) electromagnetic waves in
magnetized plasmas are determined by the plasma density and the magnetic field
strength. This property can be applied to design a unique plasma photonic
device for intense short-pulse lasers. We have demonstrated by numerical
simulations that a thin plasma foil under an external magnetic field works as a
polarizing plate to separate a linearly polarized laser into two CP waves
traveling in the opposite direction. This plasma photonic device has an
advantage for generating intense CP waves even with a relativistic amplitude.
For various research purposes, intense CP lights are strongly required to
create high energy density plasmas in the laboratory.
