Abstract

Since its recent discovery¹, photorefractivity in polymers^2-7 has attracted particular attention because photorefractive materials are versatile media for reversible optical storage applications and because organic materials like polymers have potential advantages over inorganic photorefractive crystals: low dielectric constant, ease of processing, and low cost. The capabilities of this new class of composites materials⁶ have rapidly reached a level comparable to those of some inorganic crystals and further improvement is expected since the magnitude of some intrinsic parameters such as the electro-optic coefficient for instance are not optimized yet. Here, we describe photorefractivity in azo-dye doped polymers. Azo dyes are molecules with strong second order nonlinear optical properties and are also known to undergo trans-cis photoisomerization^8-9. The azo-dye-doped polymers presented here, can store two different types of erasable holograms originating from two different physical processes: photorefractivity and trans-cis photoisomerization. We show that the strong polarization nature of the isomerization process allows isolating exclusively the photorefractive effect by selecting the polarization of the reading beam. Moreover, we discuss the possible enhancement of the read-out photorefractive efficiency by photoisomerization-assisted poling of the sample.

© 1993 Optical Society of America