Isogyration birefringent filter

A new narrow-band polarization spectral filter with an infinitely wide free spectral range is proposed. This filter utilizes the characteristics of propagation of light in a gyrotropic birefringent medium exhibiting reversal of the sign of gyration (isogyration medium). It is shown that the width of the spectral transmission maximum may reach a few angstroms and that the angle of view is limited only by the aperture of polarizing prisms.