Abstract. The Faraday effect has been investigated in various fields of study since 1845. In this paper, we provide a unified formulation of the effect for several media. In the classical case, the direction of propagation is parallel to the magnetic field. Here we generalize to any direction of propagation. When describing the state of wave polarization, we find it convenient to use the complex polarization ratio R plane. On the complex R plane, the change of polarization as the wave propagates follows a circle. The resulting polarization loci a,re illustrated for three different lossless media: a biaxial medium, a chiral medium, and a magnetoionic medium. Through the analysis of the patterns of these loci, we can visualize the generalized Faraday effect on the polarization state diagram and also gain some physical insights into these media in terms of their wave polarization characteristics.

Dimming and scattering control are two of the major features of smart windows, which provide adjustable sunlight intensity and protect the privacy of people in a building. A hybrid photo- and electrical-controllable smart window that exploits salt and photochromic dichroic dye-doped cholesteric liquid crystal was developed. The photochromic dichroic dye causes a change in transmittance from high to low upon exposure to sunlight. When the light source is removed, the smart window returns from colored to colorless. The salt-doped cholesteric liquid crystal can be bi-stably switched from transparent into the scattering state by a low-frequency voltage pulse and switched back to its transparent state by a high-frequency voltage pulse. In its operating mode, an LC smart window can be passively dimmed by sunlight and the haze can be actively controlled by applying an electrical field to it; it therefore exhibits four optical states—transparent, scattering, dark clear, and dark opaque. Each state is stable in the absence of an applied voltage. This smart window can automatically dim when the sunlight gets stronger, and according to user needs, actively adjust the haze to achieve privacy protection.

No abstract

No abstract

Bistable technology has played a vital role in the development of optical elements. Bistable technology enables zero power consumption unless the optical state needs to be changed. Salt-doped cholesteric liquid crystals (SDCLCs) have been implemented as light valves. However, the orientation mechanism of SDCLCs under different operating conditions has not been elucidated in detail. Herein, the disturbance and relaxation of SDCLCs were comprehensively investigated based on the interactions between the electrohydrodynamic and dielectric effects under different voltages, frequencies, and cell gaps. By controlling the balance between the electrohydrodynamic and dielectric effects, the bistable optical performance of SDCLC devices can be optimized for practical applications.