Abstract: Method of making a three-dimensional photonic band-gap crystal, in which a three-dimensional structure is built by successively forming a plurality of superimposed layers of photosensitive chalcogenide and creating a predetermined grating on each of them. A layer of photoresist is superimposed on each chalcogenide layer. The chalcogenide glasses are chosen among those that are photosensitive, have a high refractive index, a high ratio of high etching speed to low etching speed of at least 10. The refractive index of the glasses may be higher than 2.5. The ratio of high etching speed to low etching speed of the glasses may be at least 10.