Abstract: A diffractive unit which can reduce the effect of the nonlinearity of the photo-resist recording material to produce a diffractive device with brilliant color, and describes a method for recording. A cross grating device recorded using the method of this present invention is also described. A diffractive pattern is provided with multiple units, and the period of the diffraction within at least one of the units is spatially varying. It has been discovered that a spatially varying period can offset other effects, such nonlinear characteristics of the material or inter-unit gaps, to reduce the harmonics and improve the color.