Electrically tunable, ultranarrowband, circular-polarization rejection filters with electro-optic structurally chiral materials

The transmittance spectrum of a slab of an electro-optic structurally chiral material (SCM) that is helicoidally non homogeneous in the thickness direction and is endowed with a central 90°-twist defect, Shows evidence of an ultranarrowband spectral hole when a sufficiently high dc electric field is applied between the entry and the exit planes and the incident light is circularly polarized in opposition to the structural handedness of the SCM. this spectral hole migrates on the wavelength axis as the applied dc electric field is altered in magnitude, Thereby suggesting the possible use of a centrally defective, Electro-optic SCM slab as an electrically tunable, ircular-polarization rejection filter with ultra narrow bandwidth.