new structure for medium.py

Author: yaugenst-flex

tidy3d/components/medium/__init__.py

@@ -0,0 +1,50 @@
+from .anisotropic import AnisotropicMedium, CustomAnisotropicMedium, FullyAnisotropicMedium
+from .base import AbstractCustomMedium, AbstractMedium
+from .dispersionless import CustomMedium, Medium, PECMedium
+from .dispersive_abc import CustomDispersiveMedium, DispersiveMedium
+from .dispersive_models import (
+    CustomDebye,
+    CustomDrude,
+    CustomLorentz,
+    CustomPoleResidue,
+    CustomSellmeier,
+    Debye,
+    Drude,
+    Lorentz,
+    PoleResidue,
+    Sellmeier,
+)
+from .lossy_metal import HammerstadSurfaceRoughness, HuraySurfaceRoughness, LossyMetalMedium
+from .medium_2d import Medium2D
+from .nonlinear import KerrNonlinearity, NonlinearSpec, NonlinearSusceptibility, TwoPhotonAbsorption
+from .perturbation import PerturbationMedium, PerturbationPoleResidue
+from .utils import medium_from_nk
+
+PEC = PECMedium(name="PEC")
+PEC2D = Medium2D(ss=PEC, tt=PEC)
+
+
+def medium_from_nk(n: float, k: float, freq: float, **kwargs) -> Union[Medium, Lorentz]:
+    """Convert ``n`` and ``k`` values at frequency ``freq`` to :class:`Medium` if ``Re[epsilon]>=1``,
+    or :class:`Lorentz` if if ``Re[epsilon]<1``.
+
+    Parameters
+    ----------
+    n : float
+        Real part of refractive index.
+    k : float = 0
+        Imaginary part of refrative index.
+    freq : float
+        Frequency to evaluate permittivity at (Hz).
+    kwargs: dict
+        Keyword arguments passed to the medium construction.
+
+    Returns
+    -------
+    Union[:class:`Medium`, :class:`Lorentz`]
+        Dispersionless medium or Lorentz medium having refractive index n+ik at frequency ``freq``.
+    """
+    eps_complex = AbstractMedium.nk_to_eps_complex(n, k)
+    if eps_complex.real >= 1:
+        return Medium.from_nk(n, k, freq, **kwargs)
+    return Lorentz.from_nk(n, k, freq, **kwargs)