# InternalAbsorber

An internally placed plane with one-way wave equation boundary conditions for absorbing electromagnetic waves within the simulation domain.

Unlike domain boundary conditions, InternalAbsorber can be placed anywhere inside the simulation to absorb waves traveling in a specific direction. The absorber is automatically wrapped in a PEC frame with a backing PEC plate on the non-absorbing side.

# Size and Position

Specification of the absorber size and position.

# Center + size

Object definition through a center position and size.

center: Center of the object in x, y, and z-directions.

Type: floating-point number

  • Unit: m, μm (default), or nm
  • Default: (0, 0, 0)

size: Size of the object in x, y, and z-directions.

Type: floating-point number

  • Unit: m, μm (default), or nm
  • Constraint: greater than or equal to 0
  • Required field

# Bounds

Object definition through minimum and maximum coordinate bounds.

min: Values of the x, y, and z coordinates defining the object lower corner.

Type: floating-point number

  • Unit: m, μm (default), or nm
  • Required field

max: Values of the x, y, and z coordinates defining the object upper corner.

Type: floating-point number

  • Unit: m, μm (default), or nm
  • Required field

# Direction

direction: Indicates which direction of traveling waves are absorbed.

Options:

  • +: Absorbs waves traveling in the positive normal direction

  • -: Absorbs waves traveling in the negative normal direction

  • Required field

# Grid Shift

grid_shift: Displacement of the absorber in the normal positive direction, measured in number of grid cells.

This parameter is useful for placing an absorber directly behind a source: you can use the same size and center as the source and set the grid shift to 1.

Type: integer

  • Unit: unitless (number of cells)
  • Default: 0

# Boundary Specification

boundary_spec: Boundary specification for defining the effective propagation index in the one-way wave equation.

Options:

← ModeABCBoundary →