LARGE PHOTOREFRACTIVE EFFECT IN A THERMALLY DECOMPOSED POLYMER COMPARED WITH THAT IN MOLECULARLY DOPED SYSTEMS

Photorefractive polymers with the same electro-optic effect were fabri cated to investigate the photorefractive effects in different photocon ductive systems. The photoconduction in the polymers was varied by the addition of squarylium dye to diethylaminobenzaldehyde-diphenylhydraz one (DEH), by the formation of a charge-transfer complex between tetra cyanoquinodimethane and DEH, and by the thermal decomposition of DEH. The largest photorefractive effect was observed in the thermally decom posed polymer among these polymers. A diffraction efficiency of 1.1% a nd a beam-coupling gain coefficient of 10 cm-1 were achieved in a 34.9 V/mum dc electric field.