EMEModel

class photonforge.EMEModel(eme_grid_spec, medium=None, symmetry=(0, 0, 0), monitors=(), structures=(), grid_spec=None, subpixel=True, bounds=((None, None, None), (None, None, None)), constraint='passive', simulation_updates=None, verbose=True, _use_interface_matrix=False, _grid_transform_matrix=((1.0, 0.0), (0.0, 1.0), (0.0, 0.0)))

S matrix model based on Eigenmode Expansion calculation.

Parameters:

• eme_grid_spec (Annotated[EMEUniformGrid | EMEExplicitGrid | EMECompositeGrid, _]) – 1D grid in the that specifies the EME cells where mode solving is performed along the propagation direction.

• medium (Annotated[Medium | AnisotropicMedium | PECMedium | PMCMedium | PoleResidue | Sellmeier | Lorentz | Debye | Drude | FullyAnisotropicMedium | CustomMedium | CustomPoleResidue | CustomSellmeier | CustomLorentz | CustomDebye | CustomDrude | CustomAnisotropicMedium | PerturbationMedium | PerturbationPoleResidue | LossyMetalMedium, _] | None) – Background medium. If None, the technology default is used.

• symmetry (Annotated[Sequence[int], _]) – Component symmetries.

• monitors (Sequence[Annotated[FieldMonitor | FieldTimeMonitor | AuxFieldTimeMonitor | MediumMonitor | PermittivityMonitor | FluxMonitor | FluxTimeMonitor | ModeMonitor | ModeSolverMonitor | FieldProjectionAngleMonitor | FieldProjectionCartesianMonitor | FieldProjectionKSpaceMonitor | DiffractionMonitor | DirectivityMonitor | MicrowaveModeMonitor | MicrowaveModeSolverMonitor | GaussianOverlapMonitor | AstigmaticGaussianOverlapMonitor | SurfaceFieldMonitor | SurfaceFieldTimeMonitor, _]]) – Extra field monitors added to the simulation.

• structures (Sequence[Structure]) – Additional structures included in the simulations.

• grid_spec (Annotated[float, exclusiveMinimum=0] | GridSpec | None) – Simulation grid specification. A single float can be used to specify the min_steps_per_wvl for an auto grid.

• subpixel (SubpixelSpec | bool) – Flag controlling subpixel averaging in the simulation grid or an instance of tidy3d.SubpixelSpec.

• bounds (Annotated[Sequence[Sequence[float | None]], _]) – Bound overrides for the final simulation.

• constraint (Literal['passive', 'unitary'] | None) – Constraint for EME propagation. Possible values are "passive" and "unitary".

• simulation_updates (dict[str, object] | None) – Dictionary of updates applied to the simulation generated by this model. See example in Tidy3DModel.

• verbose (bool) – Control solver verbosity.

If not set, the default values for the component simulations are defined based on the wavelengths used in the s_matrix call.

Methods

autograd_smatrix(*, component, ...[, ...])	Compute an autograd-compatible S matrix for traced parameters.
estimate_cost(*args, **kwargs)	Estimate the cost for S matrix computation.
from_bytes(byte_repr)	De-serialize this model.
get_simulation(component, frequencies)	Create an EME simulation for a component.
s_matrix(component, frequencies[, ...])	Compute the S matrix for a component using this model.
setup_time_stepper(component, time_step[, ...])	Obtain a time stepper for a component using this model.
simulation_data(component, frequencies, *[, ...])	Return the EME simulation data for a given component.
start(component, frequencies, *[, verbose, ...])	Start computing the S matrix response from a component.
transform([translation, rotation, scaling, ...])	Apply a transformation to this model.
update(*args, **kwargs)	Update this model.

Attributes

parametric_function	Function used to update the model.
parametric_kwargs	Keyword arguments used to update the model.
properties	Object properties.
random_variables	Random variables associated to the model's parameters.
time_stepper	Time stepper associated with this model.

classmethod from_bytes(byte_repr)

De-serialize this model.

Parameters:

byte_repr (bytes)

Return type:

EMEModel

get_simulation(component, frequencies)

Create an EME simulation for a component.

Parameters:

• component (Component) – Instance of Component for calculation.

• frequencies (Sequence[float]) – Sequence of frequencies for the simulation.

Returns:

EME simulation and 2 tuples with the names of the ports on each side of the domain.

Return type:

tuple[EMESimulation, tuple[tuple[str], tuple[str]]]

simulation_data(component, frequencies, *, verbose=None, show_progress=True, **kwargs)

Return the EME simulation data for a given component.

Uses the same arguments as EMEModel.start().

Parameters:

• component (Component)

• frequencies (Sequence[float])

• verbose (bool | None)

• show_progress (bool)

• kwargs (object)

Return type:

EMESimulationData | None

start(component, frequencies, *, verbose=None, cost_estimation=False, **kwargs)

Start computing the S matrix response from a component.

Parameters:

• component (Component) – Component from which to compute the S matrix.

• frequencies (Sequence[float]) – Sequence of frequencies at which to perform the computation.

• verbose (bool | None) – If set, overrides the model’s verbose attribute.

• cost_estimation (bool) – If set, simulations are uploaded, but not executed. S matrix will not be computed.

• **kwargs (object) – Unused.

Returns:

Result object with attributes status and s_matrix.

Return type:

_EMEModelRunner

Important

When using geometry symmetry, the mode numbering in inputs is relative to the solver run with the symmetry applied, not the mode number presented in the final S matrix.

transform(translation=(0, 0), rotation=0, scaling=1, x_reflection=False)

Apply a transformation to this model.

The base implementation is a no-op and returns self. Derived classes can override this method to transform model-specific geometry settings.

Parameters:

• translation (Sequence[float] | complex) – Translation vector.

• rotation (float) – Rotation angle in degrees.

• scaling (float) – Magnification factor.

• x_reflection (bool) – Mirror across the horizontal axis.

Returns:

This object with transformations applied.

Return type:

Model