Optical Properties of Blue Phase

The optical properties of the blue phase that interest us here are the transmittance and reflectance of the material and its effect on the polarization of light These properties depend on the dielectric tensor (at optical frequencies) of the material. The dielectric tensor e is related to the 

The reflection from cholesteric and blue phases is Bragg-type scattering, similar to the diffraction of X-rays by crystals. The wave vector of the incident light Ko, the wave vector of the scattered light Kg, and the wave vector of the dielectric constant component q must satisfy the Bragg condition  

The polarization of the Bragg scattered light depends on the spherical harmonic tensor M. The intensity of the scattered hght is proportional to the structure factor [31] 

The dielectric tensor Q is defined in the local frame whose z axis is parallel to the wave vector q. 

When Ko and Ks are parallel (or anti-parallel), the wave vector q is parallel to them, and the fight propagation direction is parallel to the z axis of the local frame. The polarization vectors only have non-zero components along the x and y axes  

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Because the optical properties of blue phases are of great importance, we choose the traceless... 

The optical properties of blue phases are completely defined by the tensor of the high-frequency dielectric permittivity [93]... 

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