Design of multiorder diffraction gratings using the Rayleigh method

A method for the design of perfectly conducting multiorder diffraction gratings is proposed. The design uses the Rayleigh method and is based on the gradient search algorithm for optimization of grating structure from the condition of the generation of a desired array of diffraction orders. The developed algorithm is more general and for d >> (lambda) , where d is the grating period and (lambda) is the wavelength of incident light, goes over into the familiar gradient algorithms for designing gratings in the Kirchhoff approximation. The designs of multiorder gratings with equal order intensities are reported with the efficiency of more than 90% and root-mean-square errors of 2 - 7%.