Abstract: The present invention provides a device and method of spectral filtration of optical radiation by forming a holographic diffraction grating in a photorefractive medium. The photorefractive medium can be a crystal, a polymer or any other material with suitable photorefractive properties. The wavelength of the filtered radiation can be selected depending on the electrooptical properties of the photorefractive material, by applying an electric field and, in addition, by sufficiently high transfer function parameters achieved due to a high diffraction efficiency of the grating can be obtained.

Abstract: The present invention provides a new method for spectral filtering of optical radiation wherein the light to be filtered is directed onto two or more spaced apart layers of photosensitive material. A holographic grating is recorded in the layers so that each layer of the photosensitive material contains a portion of the recorded holographic grating. The output optical signal is formed as the result of interference of the light reflected due to the Bragg diffraction from the parts of the diffraction grating recorded in different layers. The reflected light propagates through the spaced apart electrooptical layers sandwiched between the photosensitive layers. The refractive index of the electrooptical layers is varied by the application of the appropriate electrical field to provide the phase difference between the reflected optical signals in order to obtain the desired value of the total output signal resulted from the interference of the reflected light.