  We study the scattering of an electron in a definite state of spin at an
interface of an hybrid system with a Rashba spin-orbit coupling on one side.
Out of the normal incidence the double refraction phenomenon appears, with one
or two limit angles for the total reflection. We show that this double
refraction gives rise to a spin-dependent conductance of a Quantum Point
Contact separating a ferromagnet and a two dimensional electron gas. The
birefringence allows the spin filtering with a single interface.
