The polymer poly(methyl methacrylate) (PMMA) doped with the active photoinitiator dimethoxyphenalacetophenon (DMPA) is a well known material to form permanent gratings by uv-holographie. An additional doping with the photochromic material E-(alpha) (2,5- dimethyl-3-furyl)ethylidene(adamantylidene)succinic anhydride (Aberchrome 670) leads to a one step fabrication of a nonlinear optical grating. After the permanent grating is fixed, the refractive index of the grating can be tuned by a homogenous illumination. The diffraction efficiency of the grating can be tuned because the fulgide Aberchrome 670 undergoes a reversible transition from its bleached to its colored form by homogeneous uv illumination and back again by irradiating the film with a wavelength near the absorption maximum (here (lambda) equals 514.5 nm).© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.