Abstract: A tunable optical device is produced by forming in the surface of a substrate a fan-shaped grating of continuously varying period by means of a holographic technique using a photoresist and twisted mirrors, coating the surface of the substrate containing the formed grating with a polyurethane film and diffusing a dye in the prescribed region of the resultant polyurethane film coated on the substrate. In the device of the construction described above, irradiation of the region having the fan-shaped grating with a laser light generates laser light beams whose wavelength is variable with the position at which the laser light impinges upon the region of the grating.