Optical properties of cubic blue phase liquid crystal in photonic microstructures

In this work, optical properties of a cubic blue phase liquid crystal (BPLC) in photonic microstructures were investigated. The experiments were carried out in microcapillaries with different inner diameters and in a photonic crystal fiber (PCF). For the first time, white-light beam propagation through a BPLC (BP II) in a microcapillary with a 60-μm inner diameter at a distance of 26 mm was demonstrated. Furthermore, it was conclusively shown that the cylindrical geometry and the size of its inner diameter influence BP domains orientation, which can lead to a uniform texture of the BPLC with a dominant Bragg wavelength. This study also proves that a BPLC-filled PCF provides very attractive tunable properties. It was presented that by applying an external electric field, a control of the transmitted light intensity for particular wavelengths can be achieved, depending on the input polarization. Moreover, a range of the wavelengths corresponding to low transmission appeared to be tunable, whereas for x- and y-polarized light, respectively, both narrowing (from 16 nm to 9 nm) as well widening (from 13 nm to 22 nm) of the bandgaps were observed. Finally, the obtained experimental results were found qualitatively consistent.