Abstract

Polymeric nonlinear optical materials offer a number of potential advantages over inorganic materials, particularly low cost of material, low dc dielectric constant, ease of fabrication, and compatibility with integrated optics. We report here for the first time firm evidence of photorefractivity in a nonlinear optical polymer. Photorefraction (at 647.1 nm) was established by a combination of hologram erasability, correlation with photoconductivity and electro-optic response, and enhancement by external fields in numerous samples (178 to 533 µm thick) of the polymers (BisA-NPDA)¹ or (NA-APNA)² mixed with hole transport agents such as p-diethylaminobenzaldehyde-diphenyl hydrazone (DEH). Diffraction efficiencies up to 0.1% (NA-APNA) and 0.06% (BisA-NPDA) were observed at bias fields of 84 kV/cm and 126 kV/cm, respectively. The calculated space-charge field in one sample of the BisA-NPDA mixture was 47 kV/cm (the largest yet reported in any photorefractive material) at 126 kV/cm and a grating spacing of 0.2 µm; the estimated photorefractive trap density was 6 × 10¹⁵cm⁻³.

© 1990 Optical Society of America