Holographic characterization of near infra red photopolymerizable materials

Holographic polymer dispersed liquid crystal (LC) materials with high sensitivity in the near-infra red (NIR) are studied in the present work. Materials used were already presented and are based on mixture of an acrylate monomer, LC and are sensitized in the 800-850 run region. This allows highly efficient in situ recording of holographic optical elements using infra red lasers. The holographic recording is realized by means of a Ti-Sa laser operating at 830 nm. High diffraction efficiency (95-97% in the best case) is demonstrated. Sensitivity of the material, and photochemical stability of the recorded gratings are investigated in the mentioned spectral range. The polarization dependence of gratings, recorded in these films, are examined that could be used for recovering the refractive index modulation profile. Shrinkage and switching capacity of the gratings are being currently estimated. (C) 2002 Elsevier Science B.V. All rights reserved.