The field region object is a source and monitor combination, combining the functionality of a frequency-domain monitor and a volumetric current source.
Currently, this object is only used as an input object for the Lumerical inverse design module. While settings are available in the object, the object is not intended to be used alone.
For more information on usage for the field region object for optimization problem, see the Application Gallery article on Inverse Design of Metasurface Color Router and the Knowledge Base article on Getting Started with lumopt.
General Tab
This object acts either as a source or as a monitor, but not both. The general tab changes depending on your selection on the source mode option.
Source Settings
Toggling source mode
SOURCE MODE: Toggle whether the object is used as a source.
The simulation object acts as a volumetric current source when you enable the source mode checkbox and configures the object to use the source profile in the next simulation. In this mode, the object does not behave as a monitor.
Source profile
While acting as a source, the object requires a source profile. You can import this profile using the importdataset command with a rectilinear dataset, or clear this profile using the cleardataset command.
The imported data is unaffected by switching to layout mode, for example, by using the switchtolayout command.
If no source profile is imported, the simulation will output an error.
The imported dataset must conform to the following criteria:
- The dataset must only contain an attribute of E as a function of x,y,z, and f/lambda.
- There must only be one frequency or wavelength in the dataset.
- The frequency and spatial coordinates must match that of the field region monitor.
Source mode options
BASE AMPLITUDE: The base amplitude of the source, as detailed in Units and normalization conventions in Lumerical solvers.
NUTTALL WINDOW PULSE: Toggle whether a Nuttall window is used for the current source pulse.
Monitor Settings
When you disable the source mode toggle, this simulation object is similar to the frequency-domain monitor with spatial interpolation turned off.
You cannot use cleardataset to clear the collected results. Instead, clear the results by switching to layout mode, for example, by using the switchtolayout command.
Note: The monitor settings much match that of the imported source profile. Since the source profile must only contain a single frequency, you must also set frequency points to 1 in the monitor settings.
Override global monitor settings:
A toggle to override the global monitor settings. If checked, you can specify the frequency range and number of points at which frequency-domain information will be recorded (using the options described below). If unchecked the options below are set from the global monitor settings.
SAMPLE SPACING: This combo-choice parameter determines how the sample frequency/wavelength will be selected. The three sample options are "uniform", "chebyshev" and "custom".
- USE WAVELENGTH SPACING: By default, data is recorded at certain spaced points with respect to frequency. Selecting this option spaces data at certain spaced points with respect to wavelength.
- USE SOURCE LIMITS: When checked these monitors use the source limits. When unchecked, the frequencies/wavelengths at which to record data can be set using the pull-down menus and boxes below them.
- FREQUENCY POINTS: Set to choose the number of frequency points at which to record data.
When sample spacing is selected to be "custom", all the above settings will be disabled and a "custom frequency samples" table will be shown. Properties of the table are:
- ADD: Adds an entry above the selected entry to the "frequency (THz)" table
- REMOVE: Removes the selected entry from the "frequency (THz)" table
- SORT: Sorts the table with frequency from low to high
- set global monitor settings: Access to global properties
Geometry Tab
Monitor type: The monitor type and orientation, this option will control the available of spatial setting below
- X, Y, Z: The center position of the simulation region
- X MIN, X MAX: X min, X max position
- Y MIN, Y MAX: Y min, Y max position
- Z MIN, Z MAX: Z min, Z max position
- X SPAN, Y SPAN, Z SPAN: X, Y, Z span of the simulation region
Results Returned
This object is only meant to be used with the lumopt procedure, therefore, do not use the results returned by this object in the CAD window independently.
You cannot use cleardataset to clear the results in this object. Instead, clear the results by switching to layout mode, for example, by using the switchtolayout command.
The results returned are as follows:
Results
- E: Electric field data as a function of position and frequency/wavelength.
- H: Magnetic field data as a function of position and frequency/wavelength.
- P: Poynting vector as a function of position and frequency/wavelength.
Raw data
- X, Y, Z: The x, y, and z grid of the monitor as matrices.
- DELTA_X, DELTA_Y, DELTA_Z: The grid discretization in x,y, and z as matrices
- SURFACE_NORMAL: An integer value indicating the axis perpendicular to the monitor plane for a 2-D monitor. If the monitor is not a 2-D monitor, the value is 0, for x-normal, the value is 1, for y-normal, the value is 2, and for z-normal, the value is 3.
- DIMENSION: The dimension of the FDTD simulation.
- F: The frequency grid as a matrix.
- EX, EY, EZ: Electric field values as matrices.
- HX, HY, HZ: Magnetic field values as matrices.
- POWER: Time-averaged power as a function of frequency. This data is only returned when a surface monitor (3D simulation) or line monitor (2D simulation) is used. For more information or an example using this data, see Parseval's theorem.
Material
- GRID: Grid data containing grid ID as a function of position.