# ModeSource
Injects current source to excite modal profile on finite extent plane.
# Name
name: Optional name for the source.
# Source Region
Specification of the source region.
# 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.
Use Infinity to define a geometry extending to infinity in both directions along an axis.
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: Specifies propagation in the positive or negative direction of the injection axis.
Options:
- +: Propagate in the positive direction of the injection axis
- -: Propagate in the negative direction of the injection axis
Required field
Default: +
# Number of Frequency Points
num_freqs: Number of points used to approximate the frequency dependence of injected field. A Chebyshev interpolation is used, thus, only a small number of points, i.e., less than 20, is typically sufficient to obtain converged results.
- Unit: unitless
- Constraint: greater than 0
- Default: 1
# Source Time
source_time: Specification of the source time-dependence.
Options:
Required field
Baseband source time types are available when the source already uses one, for example a source created with the Python interface. They are not offered for a new source.
# Mode Index
mode_index: Index into the collection of modes returned by mode solver. Specifies which mode to inject using this source.
If larger than num_modes in mode_spec, num_modes in the solver will be set to mode_index + 1.
# Frame
frame: Add a thin frame around the source during the FDTD run to improve the injection quality. The frame is positioned along the primal grid lines so that it aligns with the boundaries of the mode solver used to obtain the source profile.
In the editor, this appears under Advanced as Source Frame. Choose PECFrame or None.
Options:
- PECFrame: PEC source frame
- None: default
# Length
length: The length of the PEC frame, specified as the number of cells along the source injection direction. Available when PECFrame is selected.
In the editor, this is the Length field shown after choosing PECFrame.
Type: integer number
- Unit: unitless
- Constraint: greater than 0
- Default: 2
# Mode Specification
mode_spec: Parameters used by the mode solver to determine the injected modes.
See: ModeSpec
# Use Colocated Integration
use_colocated_integration: Toggle whether source integration uses colocated fields.
Options:
- False: Use the native Yee-grid field locations.
- True: Use fields colocated to grid cell boundaries.
Default: True