Electro-optical phase shift in a nano-sized polymer dispersed liquid crystal cell

Nano-sized polymer dispersed liquid crystal (PDLC) cells consist of nano-sized liquid crystal droplets embedded in a polymer matrix sandwiched between two glass substrates. Nano-sized PDLCs have been used as novel electro-optical displays with controlled optical properties and they are of great interest for fiber optics communication devices. Electro-optical phase modulation can also be achieved by the use of these materials. This effect is based on the liquid crystal orientation inside the droplets by an externally applied electric field. In this study nano-sized PDLCs have been prepared by rapid photo-polymerization of a free-radical monomer. In such a process polymerization causes changes in the chemical potential of the system and increases the miscibility gap between the liquid crystal and the polymer matrix. Thus the liquid crystal material separates as a distinct phase in the nano-sized droplets in the region of the photo-polymerization. Electro-optical phase shift of a nano-sized PDLC cell has been measured by means of a Mach-Zehnder interferometer.