Grating
Use the Grating node to create reflected and refracted rays at a boundary. By adding Diffraction Order subnodes, it is possible to release secondary rays of nonzero diffraction order. It is available on interior and exterior boundaries. Accumulator (Boundary) and Diffraction Order subnodes are available from the context menu (right-click the parent node) or from the Physics toolbar, Attributes menu. Each Diffraction Order subnode added releases a transmitted and reflected ray of the specified diffraction order. If no Diffraction Order subnodes are present, only the reflected and refracted rays of order 0 are released.
The reflected ray of order 0 and all rays of higher diffraction orders are considered secondary rays. When modeling the propagation of a large number of rays through a grating, it may be necessary to increase the Maximum number of secondary rays under the physics interface Ray Release and Propagation section.
Device Properties
Enter a Grating constant d (SI unit: m). The default is 600 nm.
For 3D components, select a Grating orientation specification — User defined (the default) or Parallel to reference edge. If Parallel to reference edge is selected, the Reference Edge Selection section is shown. Add an edge to this selection to specify the orientation of the grating. Only a single edge may be selected. The edge must be adjacent to one of the selected boundaries for the feature. If User defined is selected, enter the components of the Grating orientation direction T (dimensionless) directly.
The following settings are available when Intensity computation is set to Compute intensity, Compute intensity and power, Compute intensity in graded media, or Compute intensity and power in graded media in the physics interface Intensity Computation section:
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Enter the Reflectance R and the Transmittance T (both dimensionless).
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Select the Store total transmitted power and Store total reflected power check boxes to declare auxiliary dependent variables for the total power of all transmitted and reflected diffraction orders, respectively.
Auxiliary Dependent Variables, Refracted Ray
This section is available if an Auxiliary Dependent Variable has been added to the model. The settings are the same as for the Material Discontinuity feature.
Auxiliary Dependent Variables, Reflected Ray
This section is available if an Auxiliary Dependent Variable has been added to the model. The settings are the same as for the Material Discontinuity feature.
Grating Theory