The fluorescence of a carbazole chromophore can be activated irreversibly under optical control with the photoinduced opening of an oxazine ring. In proximity to silver nanoparticles, the quantum efficiency of this photochemical transformation and that of the emissive process increase significantly. The plasmonic effects responsible for such enhancements, together with the photochemical and photophysical properties engineered into this particular photoactivatable fluorophore, permit the optical writing and reading of microscaled patterns at low illumination intensities.