tidy3d.Sellmeier

tidy3d.Sellmeier#

class Sellmeier[source]#

Bases: DispersiveMedium

A dispersive medium described by the Sellmeier model.

Parameters:

  • name (Optional[str] = None) – Optional unique name for medium.

  • frequency_range (Optional[tuple[float, float]] = None) – [units = (Hz, Hz)]. Optional range of validity for the medium.

  • allow_gain (bool = False) – 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 (Optional[Union[NonlinearSpec, NonlinearSusceptibility]] = None) – Nonlinear spec applied on top of the base medium properties.

  • modulation_spec (Optional[ModulationSpec] = None) – Modulation spec applied on top of the base medium properties.

  • viz_spec (Optional[VisualizationSpec] = None) – Plotting specification for visualizing medium.

  • heat_spec (Optional[Union[FluidSpec, SolidSpec, SolidMedium, FluidMedium]] = None) – DEPRECATED: Use MultiPhysicsMedium. Specification of the medium heat properties. They are used for solving the heat equation via the HeatSimulation interface. Such simulations can beused 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.

  • coeffs (tuple[tuple[float, PositiveFloat], ...]) – [units = (None, um^2)]. List of Sellmeier (\(B_i, C_i\)) coefficients.

Notes

The frequency-dependence of the refractive index is described by:

\[n(\lambda)^2 = 1 + \sum_i \frac{B_i \lambda^2}{\lambda^2 - C_i}\]

For lossless, weakly dispersive materials, the best way to incorporate the dispersion without doing complicated fits and without slowing the simulation down significantly is to provide the value of the refractive index dispersion \(\frac{dn}{d\lambda}\) in tidy3d.Sellmeier.from_dispersion(). The value is assumed to be at the central frequency or wavelength (whichever is provided), and a one-pole model for the material is generated.

Example

>>> sellmeier_medium = Sellmeier(coeffs=[(1,2), (3,4)])
>>> eps = sellmeier_medium.eps_model(200e12)

See also

CustomSellmeier

A spatially varying dispersive medium described by the Sellmeier model.

Notebooks

Lectures

Attributes

coeffs

name

frequency_range

allow_gain

nonlinear_spec

modulation_spec

viz_spec

heat_spec

Methods

eps_model(frequency)

Complex-valued permittivity as a function of frequency.

from_dispersion(n, freq[, dn_dwvl])

Convert n and wavelength dispersion dn_dwvl values at frequency freq to a single-pole Sellmeier medium.
coeffs#
eps_model(frequency)[source]#

Complex-valued permittivity as a function of frequency.

classmethod from_dispersion(n, freq, dn_dwvl=0, **kwargs)[source]#

Convert n and wavelength dispersion dn_dwvl values at frequency freq to a single-pole Sellmeier medium.

Parameters:

  • n (float) – Real part of refractive index. Must be larger than or equal to one.

  • dn_dwvl (float = 0) – Derivative of the refractive index with wavelength (1/um). Must be negative.

  • freq (float) – Frequency at which n and dn_dwvl are sampled.

Returns:

Single-pole Sellmeier medium with the prvoided refractive index and index dispersion valuesat at the prvoided frequency.

Return type:

Sellmeier