Infrared linear diattenuation and birefringence spectra of ferroelectric liquid crystals

Linear diattenuation and linear birefringence spectra of three ferroelectric liquid-crystalline materials, 764E, SCE4, and SCE9, are presented for the wavelength region from 2.5 to 12 μm. Relatively high birefringence (Δn ≥ 0.1) was found in the transmission bands from 2.5 to 3.2 μm and 3.6 to 5.7 μm, with only a small amount of interference from linear diattenuation (D ≤ 2%). The potential for these materials as broad-spectral-band infrared modulators in these regions is suggested by the relatively constant retardance and small linear diattenuation. Substantially larger values of linear diattenuation and retardance are found in the narrower transmission bands beyond 5.8 μm. The linear diattenuation and linear birefringence spectra display the expected anomalous dispersion near the absorption bands.