Modes

This page provides the user with the possibility to calculate the Fourier modes and scattering matrix parameters of a grating structure, and to analyze their values as well as to draw the eigenmode field distributions. Most of the controls of this page have an obvious meaning; only a few deserve an explanation:

• The Incidence Layer edit window provides the possibility to select a layer of the structure where from an incident mode propagates towards one of the layer interfaces, and the Mode N edit windows provide the possibility to select the order of an incident mode whose effective index/permittivity is displayed under Mode Propagation control.
• The Output Layer edit window provides the possibility to choose which one of the adjacent layers or the layer itself contains the scattered mode and the Mode M edit window provides the possibility to select the order of this mode.
• The Output control informs which part (up or down) of the N to M Mode Scattering Coefficient is displayed. If the Incidence Layer and the Output Layer is the same, the Up choice means the scattering from a bottom interface the Down choice corresponds to the scattering from a top interface.
• The Polarization control (is applicable only to the diffraction orders of layers without a grating) provides the possibility to select a mode polarization type. In this case, the mode polarization is defined as Hs for H component of the Es mode electric field and as Hp for H component of the Ep mode electric field. In the general case, the concept of a definite polarization is not applicable to the modes of the grating layer, however, only two Eigen functions with conditional polarization identification of Hs and Hp correspond to each grating mode.
• The Save Modes button provides the possibility to save in a text or data file an effective index and permittivity table of all modes for the selected Incidence Layer and optionally to save an N to M Mode Scattering Coefficient table.

Note 1 If the layer index is 0 or N+1 (where N is the number of layers), this index corresponds to the cover or substrate media respectively.

Note 2 Only zero X and Y orders of a simple (without grating) layer are available.