class ModeMonitor[source]#

Bases: AbstractModeMonitor

Monitor that records amplitudes from modal decomposition of fields on plane.

  • center (Tuple[float, float, float] = (0.0, 0.0, 0.0)) – [units = um]. Center of object in x, y, and z.

  • size (Tuple[NonNegativeFloat, NonNegativeFloat, NonNegativeFloat]) – [units = um]. Size in x, y, and z directions.

  • name (ConstrainedStrValue) – Unique name for monitor.

  • interval_space (Tuple[Literal[1], Literal[1], Literal[1]] = (1, 1, 1)) – Number of grid step intervals between monitor recordings. If equal to 1, there will be no downsampling. If greater than 1, the step will be applied, but the first and last point of the monitor grid are always included. Not all monitors support values different from 1.

  • colocate (Literal[False] = False) – Defines whether fields are colocated to grid cell boundaries (i.e. to the primal grid) on-the-fly during a solver run. Can be toggled for field recording monitors and is hard-coded for other monitors depending on their specific function.

  • freqs (Union[Tuple[float, ...], ArrayLike[dtype=float, ndim=1]]) – [units = Hz]. Array or list of frequencies stored by the field monitor.

  • apodization (ApodizationSpec = ApodizationSpec(start=None, end=None, width=None, type='ApodizationSpec')) – Sets parameters of (optional) apodization. Apodization applies a windowing function to the Fourier transform of the time-domain fields into frequency-domain ones, and can be used to truncate the beginning and/or end of the time signal, for example to eliminate the source pulse when studying the eigenmodes of a system. Note: apodization affects the normalization of the frequency-domain fields.

  • mode_spec (ModeSpec) – Parameters to feed to mode solver which determine modes measured by monitor.

  • store_fields_direction (Optional[Literal['+', '-']] = None) – Propagation direction for the mode field profiles stored from mode solving.


The fields recorded by frequency monitors (and hence also mode monitors) are automatically normalized by the power amplitude spectrum of the source. For multiple sources, the user can select which source to use for the normalization too.

We can also use the mode amplitudes recorded in the mode monitor to reveal the decomposition of the radiated power into forward- and backward-propagating modes, respectively.


>>> mode_spec = ModeSpec(num_modes=3)
>>> monitor = ModeMonitor(
...     center=(1,2,3),
...     size=(2,2,0),
...     freqs=[200e12, 210e12],
...     mode_spec=mode_spec,
...     name='mode_monitor')

See also




storage_size(num_cells, tmesh)

Size of monitor storage given the number of points after discretization.

Inherited Common Usage

storage_size(num_cells, tmesh)[source]#

Size of monitor storage given the number of points after discretization.


Hash method.