COMMENT ON NONLINEAR-ANALYSIS FOR REFLECTION HOLOGRAMS (OPTICS-COMM 107 (1994) 471)

In a recent paper [Optics Comm. 107 (1994) 471] Liu and Zhou have pres ented an analysis of non-sinusoidal holographically recorded volume re flection gratings. In this comment it is pointed out that the nonlinea r coupled wave equations, which the authors state cannot be solved num erically, have previously been solved directly. Using this method of a nalysis quantitative comparisons with experimental results for reflect ion gratings recorded in Dichromated Gelatin, DCG, have previously bee n presented in the literature. Other difficulties arising due to the q ualitative nature of the authors comparison of theory and experiment a re also discussed.