Polarization holographic grating recording in a liquid crystalline azo dye copolymer with hidden helical superstructure

Abstract

The polarization holographic grating recording in a liquid crystalline photopolymer with hidden helical superstructure (P8 *NN) is reported. It has been demonstrated that this photosensitive polymer could be utilized both for the recording of both the amplitude and the polarization holographic gratings. Diffraction efficiency of several diffraction orders (up to ±4 orders) has been measured for different intensities of the recording light beams. A detailed investigation was devoted to the polarization holographic recording. It is shown that the diffraction efficiency strongly depends on the polarization state of the probing He-Ne laser beam. The maximum achieved diffraction efficiency (for +1 order) was about 30%. The possible mechanisms responsible for the grating recording are trans-cis isomerization and photo-orientation of liquid crystalline terminal ends. This material with highly efficient polarization gratings is promising for polarimetric and interferomeric applications. © 2012 The Royal Swedish Academy of Sciences.