Abstract
Different types of tunable and reconfigurable holographic filters based on photorefractive crystals are demonstrated experimentally. The filters exhibit an extremely narrow bandwidth (better than 0.1 nm) and allow reconfiguration or switching in a broad wavelength range and precise fast electro-optical frequency trimming. An on-line transformation of the transfer function of a narrow-band optical filter by introducing a π-shift into a holographic grating has been demonstrated for a dynamic holographic filter in BaTiO3. Some of the most promising applications of photorefractive optical filters are discussed.