tidy3d.Lorentz

class Lorentz

Bases: DispersiveMedium

A dispersive medium described by the Lorentz model.

Parameters:

• name (Attribute: name) –

  Type	Optional[str]
  Default	= None
  Description	Optional unique name for medium.

• frequency_range (Attribute: frequency_range) –

  Type	Optional[Tuple[float, float]]
  Default	= None
  Units	(Hz, Hz)
  Description	Optional range of validity for the medium.

• allow_gain (Attribute: allow_gain) –

  Type	bool
  Default	= False
  Description	Allow the medium to be active. Caution: simulations with a gain medium are unstable, and are likely to diverge.Simulations where ‘allow_gain’ is set to ‘True’ will still be charged even if diverged. Monitor data up to the divergence point will still be returned and can be useful in some cases.

• nonlinear_spec (Attribute: nonlinear_spec) –

  Type	Union[NonlinearSpec, NonlinearSusceptibility]
  Default	= None
  Description	Nonlinear spec applied on top of the base medium properties.

• modulation_spec (Attribute: modulation_spec) –

  Type	Optional[ModulationSpec]
  Default	= None
  Description	Modulation spec applied on top of the base medium properties.

• heat_spec (Attribute: heat_spec) –

  Type	Union[FluidSpec, SolidSpec, NoneType]
  Default	= None
  Description	Specification of the medium heat properties. They are used for solving the heat equation via the HeatSimulation interface. Such simulations can be used for investigating the influence of heat propagation on the properties of optical systems. Once the temperature distribution in the system is found using HeatSimulation object, Simulation.perturbed_mediums_copy() can be used to convert mediums with perturbation models defined into spatially dependent custom mediums. Otherwise, the heat_spec does not directly affect the running of an optical Simulation.

• eps_inf (Attribute: eps_inf) –

  Type	PositiveFloat
  Default	= 1.0
  Units	None (relative permittivity)
  Description	Relative permittivity at infinite frequency (\(\epsilon_\infty\)).

• coeffs (Attribute: coeffs) –

  Type	Tuple[Tuple[float, float, pydantic.v1.types.NonNegativeFloat], …]
  Default
  Units	(None (relative permittivity), Hz, Hz)
  Description	List of (\(\Delta\epsilon_i, f_i, \delta_i\)) values for model.

Notes

The frequency-dependence of the complex-valued permittivity is described by:

\[\epsilon(f) = \epsilon_\infty + \sum_i \frac{\Delta\epsilon_i f_i^2}{f_i^2 - 2jf\delta_i - f^2}\]

Example

>>> lorentz_medium = Lorentz(eps_inf=2.0, coeffs=[(1,2,3), (4,5,6)])
>>> eps = lorentz_medium.eps_model(200e12)

See also

Notebooks

• Fitting dispersive material models

Lectures

• Modeling dispersive material in FDTD

Attributes

Methods

eps_model(frequency)	Complex-valued permittivity as a function of frequency.
from_nk(n, k, freq, **kwargs)	Convert n and k values at frequency freq to a single-pole Lorentz medium.

eps_inf

coeffs

eps_model(frequency)

Complex-valued permittivity as a function of frequency.

classmethod from_nk(n, k, freq, **kwargs)

Convert n and k values at frequency freq to a single-pole Lorentz medium.

Parameters:

• n (float) – Real part of refractive index.

• k (float = 0) – Imaginary part of refrative index.

• freq (float) – Frequency to evaluate permittivity at (Hz).

Returns:

Lorentz medium having refractive index n+ik at frequency freq.

Return type:

Lorentz

__hash__()

Hash method.