Transition Boundary Condition
The Transition Boundary Condition is used on interior boundaries to model a sheet of a medium that should be geometrically thin but does not have to be electrically thin. It represents a discontinuity in the tangential electric field. Mathematically it is described by a relation between the electric field discontinuity and the induced surface current density:
where indices 1 and 2 refer to the different sides of the layer. This feature is not available with the Electromagnetic Waves, Transient interface.
The Transition Boundary Condition is based on the assumption that the wave propagates in the normal direction in the thin layer. Thus, the wave could be incident in the normal direction or the wave could be refracted to propagate in a direction close to the normal direction. The latter condition is fulfilled for a good conductor.
The thickness of the layer should also be less than the radius of curvature for the boundary and the material properties in the thin layer are assumed to be isotropic.
A consequence of the normal direction propagation assumption is that the Transition Boundary Condition is not compatible with mode analysis, as for mode analysis it is assumed that the wave predominantly propagates in the out-of-plane direction whereas the normal to the boundary is in an in-plane direction.
For the Electromagnetic Waves, Beam Envelopes interface, the propagation in the layer can be specified to be given from the wave vectors specified for the physics and Snell’s law of refraction. For this option, the assumption of normal propagation in the layer is not required. Thus, this option is useful also when the layer is a dielectric material.
When adding a Transition Boundary Condition node, the phase specified for the Electromagnetic Waves, Beam Envelopes interface can be discontinuous.
The Surface Current Density subnode is available from the context menu (right-click the parent node) or from the Physics toolbar, Attributes menu.
Propagation Direction
This section is only available for the Electromagnetic Waves, Beam Envelopes interface. Select a Propagation direction — Normal direction (the default) or From wave vector. The Normal direction option assumes that the waves in the layer propagate essentially in the normal direction, whereas the From wave vector option assumes that the tangential wave vector component is continuous at the layer boundaries, as specified by the wave vectors k1 and k2 for the Electromagnetic Waves, Beam Envelopes interface. The normal component for the wave vector in the layer is obtained from the wave number, given the specified material parameters. Thus, this option implements Snell’s law of refraction for the layer, which makes this option useful also for dielectric layers.
Transition Boundary Condition
Select an Electric displacement field model — Relative permittivity, Refractive index (the default), Loss tangent, loss angle, Loss tangent, dissipation factor, Dielectric loss, Drude-Lorentz dispersion model, Debye dispersion model, or Sellmeier dispersion model. See the Wave Equation, Electric node, Electric Displacement Field section, for all settings. However, notice that only isotropic (scalar) material parameters are supported for this boundary condition.
Select the Electrically thick layer check box (cleared by default) to make the two domains adjacent to the boundary uncoupled. Use this setting, for instance, when the thickness is greater than three times of the skin depth. When the Electrically thick layer check box is cleared, enter a Thickness d (SI unit: m). The default is 0.01 m.
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Beam Splitter: Application Library path Wave_Optics_Module/Optical_Scattering/beam_splitter
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Focusing Lens: Application Library path Wave_Optics_Module/Verification_Examples/focusing_lens
Resonance Constraint
To display this section, click the Show More Options button () and select Advanced Physics Options in the Show More Options dialog box. Select the Activate resonance constraint check box to apply the constraint to address resonance conditions, for lossless materials when the entered Thickness d is an integer number of half wavelengths. It is checked by default.
Skin Depth Calculator
Select a Defined by option — Electrical conductivity (default) or Resistivity. Enter a Electrical conductivity σ (SI unit: S/m), Relative permittivity εr, Relative permeability μr of the material to be evaluated, and frequency f0 (SI unit: Hz). Then click the Compute Skin Depth button to compute the skin depth for the particular material specified by the above input values. The result is displayed in the settings window below the Compute Skin Depth button.