tidy3d.Medium#
- class Medium[source]#
Bases:
AbstractMedium
Dispersionless medium. Mediums define the optical properties of the materials within the simulation.
- Parameters:
attrs (dict = {}) – Dictionary storing arbitrary metadata for a Tidy3D object. This dictionary can be freely used by the user for storing data without affecting the operation of Tidy3D as it is not used internally. Note that, unlike regular Tidy3D fields,
attrs
are mutable. For example, the following is allowed for setting anattr
obj.attrs['foo'] = bar
. Also note that Tidy3D` will raise aTypeError
ifattrs
contain objects that can not be serialized. One can check ifattrs
are serializable by callingobj.json()
.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 (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.
heat_spec (Union[FluidSpec, SolidSpec, NoneType] = None) – 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 usingHeatSimulation
object,Simulation.perturbed_mediums_copy()
can be used to convert mediums with perturbation models defined into spatially dependent custom mediums. Otherwise, theheat_spec
does not directly affect the running of an opticalSimulation
.permittivity (Union[ConstrainedFloatValue, Box] = 1.0) – [units = None (relative permittivity)]. Relative permittivity.
conductivity (Union[float, Box] = 0.0) – [units = S/um]. Electric conductivity. Defined such that the imaginary part of the complex permittivity at angular frequency omega is given by conductivity/omega.
Notes
In a dispersion-less medium, the displacement field \(D(t)\) reacts instantaneously to the applied electric field \(E(t)\).
\[D(t) = \epsilon E(t)\]Example
>>> dielectric = Medium(permittivity=4.0, name='my_medium') >>> eps = dielectric.eps_model(200e12)
See also
- Notebooks
- Lectures
- GUI
Attributes
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
compute_derivatives
(derivative_info)Compute the adjoint derivatives for this object.
derivative_eps_complex_volume
(E_der_map, bounds)Get the derivative w.r.t complex-valued permittivity in the volume.
derivative_eps_sigma_volume
(E_der_map, bounds)Get the derivative w.r.t permittivity and conductivity in the volume.
eps_model
(frequency)Complex-valued permittivity as a function of frequency.
from_nk
(n, k, freq, **kwargs)Convert
n
andk
values at frequencyfreq
toMedium
.Inherited Common Usage
- permittivity#
- conductivity#
- 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
.For dispersiveless medium, it equals
sqrt(permittivity)
.
- classmethod from_nk(n, k, freq, **kwargs)[source]#
Convert
n
andk
values at frequencyfreq
toMedium
.- 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:
medium containing the corresponding
permittivity
andconductivity
.- Return type:
- derivative_eps_sigma_volume(E_der_map, bounds)[source]#
Get the derivative w.r.t permittivity and conductivity in the volume.
- derivative_eps_complex_volume(E_der_map, bounds)[source]#
Get the derivative w.r.t complex-valued permittivity in the volume.
- __hash__()#
Hash method.