Analysis of gratings with symmetrical and unsymmetrical periods

The paper shows how gratings can be analyzed in an efficient way. In the case of symmetrical periods, the Floquet modes can be obtained from the input impedance by open circuiting the output and the input admittance by short circuiting the output of the period and even from half of the period. In case of unsymmetrical periods, the E- and H-fields together form the Floquet modes. Because the Floquet mode system is a complete system, we can analyze, e.g., finite periodic fibre sections with homogeneous fibers at the input and output.