tidy3d.ModeData

class ModeData

Bases: MonitorData

Data associated with a ModeMonitor: modal amplitudes and propagation indices.

Parameters:

• monitor (Attribute: monitor) –

  Type	ModeMonitor
  Default
  Description	Mode monitor associated with the data.

• amps (Attribute: amps) –

  Type	ModeAmpsDataArray
  Default
  Description	Complex-valued amplitudes associated with the mode.

• n_complex (Attribute: n_complex) –

  Type	ModeIndexDataArray
  Default
  Description	Complex-valued effective propagation constants associated with the mode.

• n_group_raw (Attribute: n_group_raw) –

  Type	Optional[GroupIndexDataArray]
  Default	= None
  Description	Index associated with group velocity of the mode.

• dispersion_raw (Attribute: dispersion_raw) –

  Type	Optional[ModeDispersionDataArray]
  Default	= None
  Units	ps/(nm km)
  Description	Dispersion parameter for the mode.

Notes

The data is stored as a DataArray object using the xarray package.

The mode monitor data contains the complex effective indices and the complex mode amplitudes at the monitor position calculated by mode decomposition. The data structure of the complex effective indices :attr`n_complex` contains two coordinates: f and mode_index, both of which are specified when defining the :class:ModeMonitor in the simulation.

Besides the effective index, :class:ModeMonitor is primarily used to calculate the transmission of certain modes in certain directions. We can extract the complex amplitude and square it to compute the mode transmission power.

Example

>>> from tidy3d import ModeSpec
>>> from tidy3d import ModeAmpsDataArray, ModeIndexDataArray
>>> direction = ["+", "-"]
>>> f = [1e14, 2e14, 3e14]
>>> mode_index = np.arange(5)
>>> index_coords = dict(f=f, mode_index=mode_index)
>>> index_data = ModeIndexDataArray((1+1j) * np.random.random((3, 5)), coords=index_coords)
>>> amp_coords = dict(direction=direction, f=f, mode_index=mode_index)
>>> amp_data = ModeAmpsDataArray((1+1j) * np.random.random((2, 3, 5)), coords=amp_coords)
>>> monitor = ModeMonitor(
...    size=(2,0,6),
...    freqs=[2e14, 3e14],
...    mode_spec=ModeSpec(num_modes=5),
...    name='mode',
... )
>>> data = ModeData(monitor=monitor, amps=amp_data, n_complex=index_data)

Attributes

dispersion	Dispersion parameter.
k_eff	Imaginary part of the propagation index.
n_eff	Real part of the propagation index.
n_group	Group index.

Methods

normalize(source_spectrum_fn)

Return copy of self after normalization is applied using source spectrum function.

monitor

amps

n_complex

n_group_raw

dispersion_raw

property n_eff

Real part of the propagation index.

property k_eff

Imaginary part of the propagation index.

property n_group

Group index.

property dispersion

Dispersion parameter.

\[D = -\frac{\lambda}{c_0} \frac{{\rm d}^2 n_{\text{eff}}}{{\rm d}\lambda^2}\]

normalize(source_spectrum_fn)

Return copy of self after normalization is applied using source spectrum function.

__hash__()

Hash method.