Formation of holographic gratings in polymer-dispersed liquid crystals using off-resonant light

This paper presents the electro-optical characteristics of polarization-independent holographic gratings (HGs) recorded in polymer-dispersed liquid crystals (PDLCs) using off-resonant laser beam. The key mechanism is based on the low light absorbance by the materials used, which enables a slow polymerization-induced phase separation. The off-resonant light can penetrate through the cell without much energy loss (absorbance) and can be uniformly absorbed across the LC cell to produce uniform PDLC structures. The intensity-modulated interference field, which is generated by two linearly polarized off-resonant laser beams, is adopted to record the HGs. The fabricated HGs are electrically switchable and polarization independent. Moreover, the diffractions of the HGs fabricated using off-resonant light is better than those produced by resonant light.