Computer-aided algorithm based on the Yasuura method for analysis of diffraction by a grating

Modifying the least-squares problem arising in the Yasuura method, we establish a computer-aided algorithm for the numerical solution of the diffraction problems for a grating having a smooth profile. In the algorithm, the least-squares problem is solved by the QR algorithm method. As a result, the present algorithm enables us to find the precise solutions for a wider range of problems in comparison with those found by the previous algorithm. This is demonstrated by numerical examples. Also it is shown that the diffraction efficiency of gratings with various groove profiles is calculated with a high accuracy for both E- and H-wave incidences.