We have fabricated electrically switchable holographic gratings, using Pola
roid Corporation's DMP-128 photopolymer filled with the nematic liquid crys
tal E7. It is shown that a coupled-wave theory that includes the effects of
the birefringence of the Liquid crystal must be used to explain the diffra
ction properties of these anisotropic volume gratings. Furthermore, a detai
led comparison of theory and experiment provides information about the alig
nment of the liquid crystal within the polymer host. (C) 2000 Optical Socie
ty of America OCIS codes: 090.7330, 230.1950, 230.3720.