Improvement of the diffraction properties in holographic polymer dispersed liquid crystal bragg gratings

Holographic polymer dispersed liquid crystal (HPDLC) is a new kind of holographic material. It can be fabricated by the photo-initiated polymerization-induced phase separation. HPDLC Bragg grating is composed of parallel, periodic polymer-rich and liquid crystal-rich lamellae. The diffraction efficiency (DE) can be switched by the application of electric field. HPDLC devices are potentially useful for optical communication, information storage and display. How to increase the diffraction efficiency is the key to application. We investigated the dependence of DE on different monomers, liquid crystal content, exposure intensity and time, and exposure temperature. The best conditions were founded to make the diffraction properties improved. Now the highest DE was 80.2%. The HPDLC grating morphologies were also observed and analyzed by scanning electron microscope (SEM). (C) 2003 Elsevier Science B.V. All rights reserved.