class FieldMonitor[source]#

Bases: AbstractFieldMonitor, FreqMonitor

Monitor that records electromagnetic fields in the frequency domain.

  • attrs (dict = {}) – Dictionary storing arbitrary metadata for a Tidy3D object. This dictionary can be freely used by the user for storing data without affecting the operation of Tidy3D as it is not used internally. Note that, unlike regular Tidy3D fields, attrs are mutable. For example, the following is allowed for setting an attr obj.attrs['foo'] = bar. Also note that Tidy3D` will raise a TypeError if attrs contain objects that can not be serialized. One can check if attrs are serializable by calling obj.json().

  • center (Union[tuple[Union[float, autograd.tracer.Box], Union[float, autograd.tracer.Box], Union[float, autograd.tracer.Box]], Box] = (0.0, 0.0, 0.0)) – [units = um]. Center of object in x, y, and z.

  • size (Union[tuple[Union[pydantic.v1.types.NonNegativeFloat, autograd.tracer.Box], Union[pydantic.v1.types.NonNegativeFloat, autograd.tracer.Box], Union[pydantic.v1.types.NonNegativeFloat, autograd.tracer.Box]], Box]) – [units = um]. Size in x, y, and z directions.

  • name (ConstrainedStrValue) – Unique name for monitor.

  • interval_space (Tuple[PositiveInt, PositiveInt, PositiveInt] = (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.

  • colocate (bool = True) – Toggle whether fields should be colocated to grid cell boundaries (i.e. primal grid nodes).

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

  • apodization (ApodizationSpec = ApodizationSpec(attrs={}, 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.

  • fields (Tuple[Literal['Ex', 'Ey', 'Ez', 'Hx', 'Hy', 'Hz'], ...] = ['Ex', 'Ey', 'Ez', 'Hx', 'Hy', 'Hz']) – Collection of field components to store in the monitor.


FieldMonitor objects operate by running a discrete Fourier transform of the fields at a given set of frequencies to perform the calculation “in-place” with the time stepping. FieldMonitor objects are useful for investigating the steady-state field distribution in 2D and 3D regions of the simulation.


>>> monitor = FieldMonitor(
...     center=(1,2,3),
...     size=(2,2,2),
...     fields=['Hx'],
...     freqs=[250e12, 300e12],
...     name='steady_state_monitor',
...     colocate=True)

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.