NEW METHOD FOR THE FABRICATION OF STRATIFIED GRATINGS AND THEIR APPLICATIONS

A new method for the preparation of stratified light-sensitive film is developed, and the stratified gratings (SG's) are recorded in the fil m. The sensitive layers on both sides of a dichromated cellulose triac etate film are produced simultaneously through chemical reaction and n ot with the conventional coating technique. Compared with SG's in othe r materials made with coating techniques, double-layer SG's in the fil m have, to my knowledge, the highest experimental diffraction efficien cy (similar to 54%) in addition to their having a simple recording opt ical system. The diffraction efficiency and the periodic Bragg selecti vity of the SH in the film is given. Based on the SG's of the film, se veral beam splitters with 2, 3, 4, or 7 fan-outs and higher than 80% t otal diffraction efficiencies are realized experimentally. The advanta ges of this method as compared with others, such as the method based o n volume holographic beam splitters, are explained.