**One-Step Holographic Photoalignment for Twisted Nematic Liquid Crystal Gratings** One-Step Holographic Photoalignment for Twisted

Kotaro Kawai, Moritsugu Sakamoto, Kohei Noda, Tomoyuki Sasaki, Nobuhiro Kawatsuki and Hiroshi Ono Kotaro Kawai, Moritsugu Sakamoto, Kohei Noda, Tomoyuki Sasaki,

Additional information is available at the end of the chapter Nobuhiro Kawatsuki and Hiroshi Ono Additional information is available at the end of the chapter

Nematic Liquid Crystal Gratings

http://dx.doi.org/10.5772/67293

#### Abstract

Liquid crystal gratings, in which liquid crystal molecules are periodically aligned, are fabricated by highly efficient and practical one-step holographic photoalignment method using a photocrosslinkable polymer liquid crystal (PCLC). This method is an innovative fabrication technique for liquid crystal grating containing a twisted nematic alignment, which does not require a conventional complex fabrication process. In this chapter, three types of liquid crystal gratings with twisted nematic alignment are fabricated. Periodic director distributions of these liquid crystal gratings are analyzed based on the elastic continuum theory and observed experimentally using a polarized light optical microscope. Furthermore, the polarization diffraction properties were measured by illumination with a visible laser beam. The resultant liquid crystal gratings exhibit various polarization diffraction properties depending on the director distributions and the polarization states of the incident beams. These polarization diffraction properties are well explained by theoretical analysis based on Jones calculus. These resultant liquid crystal gratings exhibit great potential for application as a diffractive optical element that can simultaneously control the various parameters of the light wave, such as amplitude, polarization states, and propagation direction.

Keywords: diffraction gratings, liquid crystals, polarization, Jones calculus, photocrosslinkable polymer liquid crystals
