The present invention relates to an amplifying medium for solid-state dye lasers and to a solid-state dye laser provided with an amplifying medium of this type. The amplifying medium according to the invention comprises an essentially solid active medium which contains at least one type of activatable particle which can be excited to emit laser light in a certain wavelength range, and optical feedback means which define a resonator for the laser light, where the feedback means comprise an essentially solid feedback medium which has a periodic structure. The feedback medium in the amplifying medium is a polymeric dispersion film having a crystalline structure which comprises, in particular, core/shell particles which can be formed into a film.