The transmittance of ZnAs2 crystals in the transparency range was found to
depend on light polarization, photon energy, and sample thickness. This eff
ect is attributed to peculiar light propagation in ZnAs2, associated with t
he nonuniformity of the refractive index, sensitive to light polarization.
The anomalous light propagation should be taken into account in determining
the true absorption coefficient. The effect in question, revealed in both
ZnAs2 and CdP4 crystals, can be used to produce IR polarizers.