tidy3d.Medium2D

class Medium2D

Bases: AbstractMedium

2D diagonally anisotropic medium.

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.

• ss (Attribute: ss) –

  Type	Union[Medium, PoleResidue, Sellmeier, Lorentz, Debye, Drude, PECMedium]
  Default
  Description	Medium describing the ss-component of the diagonal permittivity tensor. The ss-component refers to the in-plane dimension of the medium that is the first component in order of ‘x’, ‘y’, ‘z’. If the 2D material is normal to the y-axis, for example, then this determines the xx-component of the corresponding 3D medium.

• tt (Attribute: tt) –

  Type	Union[Medium, PoleResidue, Sellmeier, Lorentz, Debye, Drude, PECMedium]
  Default
  Description	Medium describing the tt-component of the diagonal permittivity tensor. The tt-component refers to the in-plane dimension of the medium that is the second component in order of ‘x’, ‘y’, ‘z’. If the 2D material is normal to the y-axis, for example, then this determines the zz-component of the corresponding 3D medium.

Notes

Only diagonal anisotropy is currently supported.

Example

>>> drude_medium = Drude(eps_inf=2.0, coeffs=[(1,2), (3,4)])
>>> medium2d = Medium2D(ss=drude_medium, tt=drude_medium)

Attributes

elements	The diagonal elements of the 2D medium as a dictionary.
is_pec	Whether the medium is a PEC.
n_cfl	This property computes the index of refraction related to CFL condition, so that the FDTD with this medium is stable when the time step size that doesn't take material factor into account is multiplied by n_cfl.

Methods

eps_diagonal(frequency)	Main diagonal of the complex-valued permittivity tensor as a function of frequency.
eps_model(frequency)	Complex-valued permittivity as a function of frequency.
from_anisotropic_medium(medium, axis, thickness)	Generate a Medium2D equivalent of a AnisotropicMedium with given normal axis and thickness.
from_dispersive_medium(medium, thickness)	Generate a Medium2D equivalent of a DispersiveMedium with a given thickness.
from_medium(medium, thickness)	Generate a Medium2D equivalent of a Medium with a given thickness.
is_comp_pec_2d(comp, axis)	Whether the medium is a PEC.
plot(freqs[, ax])	Plot n, k of a Medium as a function of frequency.
plot_sigma(freqs[, ax])	Plot the surface conductivity of the 2D material.
sigma_model(freq)	Complex-valued conductivity as a function of frequency.
to_anisotropic_medium(axis, thickness)	Generate a 3D AnisotropicMedium equivalent of a given thickness.
to_medium(thickness)	Generate a Medium equivalent of a given thickness.
to_pole_residue(thickness)	Generate a PoleResidue equivalent of a given thickness.
volumetric_equivalent(axis, adjacent_media, ...)	Produces a 3D volumetric equivalent medium.

ss

tt

volumetric_equivalent(axis, adjacent_media, adjacent_dls)

Produces a 3D volumetric equivalent medium. The new medium has thickness equal to the average of the dls in the axis direction. The ss and tt components of the 2D material are mapped in order onto the xx, yy, and zz components of the 3D material, excluding the axis component. The conductivity and residues (in the case of a dispersive 2D material) are rescaled by 1/dl. The neighboring media neighbors enter in as a background for the resulting volumetric equivalent.

Parameters:

• axis (Axis) – Index (0, 1, or 2 for x, y, or z respectively) of the normal direction to the 2D material.

• adjacent_media (Tuple[MediumType3D, MediumType3D]) – The neighboring media on either side of the 2D material. The first element is directly on the - side of the 2D material in the supplied axis, and the second element is directly on the + side.

• adjacent_dls (Tuple[float, float]) – Each dl represents twice the thickness of the desired volumetric model on the respective side of the 2D material.

Returns:

The 3D material corresponding to this 2D material.

Return type:

AnisotropicMedium

to_anisotropic_medium(axis, thickness)

Generate a 3D AnisotropicMedium equivalent of a given thickness.

Parameters:

• axis (Axis) – The normal axis to the 2D medium.

• thickness (float) – The thickness of the desired 3D medium.

Returns:

The 3D equivalent of this 2D medium.

Return type:

AnisotropicMedium

to_pole_residue(thickness)

Generate a PoleResidue equivalent of a given thickness. The 2D medium to be isotropic in-plane (otherwise the components are averaged).

Parameters:

thickness (float) – The thickness of the desired 3D medium.

Returns:

The 3D equivalent pole residue model of this 2D medium.

Return type:

PoleResidue

to_medium(thickness)

Generate a Medium equivalent of a given thickness. The 2D medium must be isotropic in-plane (otherwise the components are averaged) and non-dispersive besides a constant conductivity.

Parameters:

thickness (float) – The thickness of the desired 3D medium.

Returns:

The 3D equivalent of this 2D medium.

Return type:

Medium

classmethod from_medium(medium, thickness)

Generate a Medium2D equivalent of a Medium with a given thickness.

Parameters:

• medium (Medium) – The 3D medium to convert.

• thickness (float) – The thickness of the 3D material.

Returns:

The 2D equivalent of the given 3D medium.

Return type:

Medium2D

classmethod from_dispersive_medium(medium, thickness)

Generate a Medium2D equivalent of a DispersiveMedium with a given thickness.

Parameters:

• medium (DispersiveMedium) – The 3D dispersive medium to convert.

• thickness (float) – The thickness of the 3D material.

Returns:

The 2D equivalent of the given 3D medium.

Return type:

Medium2D

classmethod from_anisotropic_medium(medium, axis, thickness)

Generate a Medium2D equivalent of a AnisotropicMedium with given normal axis and thickness. The ss and tt components of the resulting 2D medium correspond to the first of the xx, yy, and zz components of the 3D medium, with the axis component removed.

Parameters:

• medium (AnisotropicMedium) – The 3D anisotropic medium to convert.

• axis (Axis) – The normal axis to the 2D material.

• thickness (float) – The thickness of the 3D material.

Returns:

The 2D equivalent of the given 3D medium.

Return type:

Medium2D

eps_model(frequency)

Complex-valued permittivity as a function of frequency.

eps_diagonal(frequency)

Main diagonal of the complex-valued permittivity tensor as a function of frequency.

plot(freqs, ax=None)

Plot n, k of a Medium as a function of frequency.

plot_sigma(freqs, ax=None)

Plot the surface conductivity of the 2D material.

sigma_model(freq)

Complex-valued conductivity as a function of frequency.

Parameters:

freq (float) – Frequency to evaluate conductivity at (Hz).

Returns:

Complex conductivity at this frequency.

Return type:

complex

property elements

The diagonal elements of the 2D medium as a dictionary.

property n_cfl

This property computes the index of refraction related to CFL condition, so that the FDTD with this medium is stable when the time step size that doesn’t take material factor into account is multiplied by n_cfl.

property is_pec

Whether the medium is a PEC.

is_comp_pec_2d(comp, axis)

Whether the medium is a PEC.

__hash__()

Hash method.