class ComplexPolySlab[source]#

Bases: ComplexPolySlabBase

Interface for dividing a complex polyslab where self-intersecting polygon can occur during extrusion.

  • axis (Literal[0, 1, 2] = 2) – Specifies dimension of the planar axis (0,1,2) -> (x,y,z).

  • sidewall_angle (ConstrainedFloatValue = 0.0) – [units = rad]. Angle of the sidewall. sidewall_angle=0 (default) specifies a vertical wall; 0<sidewall_angle<np.pi/2 specifies a shrinking cross section along the axis direction; and -np.pi/2<sidewall_angle<0 specifies an expanding cross section along the axis direction.

  • reference_plane (Literal['bottom', 'middle', 'top'] = middle) – The position of the plane where the supplied cross section are defined. The plane is perpendicular to the axis. The plane is located at the bottom, middle, or top of the geometry with respect to the axis. E.g. if axis=1, bottom refers to the negative side of the y-axis, and top refers to the positive side of the y-axis.

  • slab_bounds (Tuple[float, float]) – [units = um]. Minimum and maximum positions of the slab along axis dimension.

  • dilation (float = 0.0) – [units = um]. Dilation of the supplied polygon by shifting each edge along its normal outwards direction by a distance; a negative value corresponds to erosion.

  • vertices (ArrayLike[dtype=float, ndim=2]) – [units = um]. List of (d1, d2) defining the 2 dimensional positions of the polygon face vertices at the reference_plane. The index of dimension should be in the ascending order: e.g. if the slab normal axis is axis=y, the coordinate of the vertices will be in (x, z)


>>> import tidy3d as td
>>> from tidy3d.plugins.polyslab import ComplexPolySlab
>>> vertices = ((0, 0), (1, 0), (1, 1), (0, 1), (0, 0.9), (0, 0.11))
>>> p = ComplexPolySlab(vertices=vertices, axis=2, slab_bounds=(0, 1), sidewall_angle=0.785)
>>> # To obtain the divided polyslabs, there are two approaches:
>>> # 1) a list of divided polyslabs
>>> geo_list = p.sub_polyslabs
>>> # 2) geometry group containing the divided polyslabs
>>> geo_group = p.geometry_group
>>> # Or directly obtain the structure with a user-specified medium
>>> mat = td.Medium(permittivity=2)
>>> structure = p.to_structure(mat)


This version is limited to neighboring vertex-vertex crossing type of self-intersecting events. Extension to cover all types of self-intersecting events is expected in the future.

The algorithm is as follows (for the convenience of illustration, let’s consider the reference plane to lie at the bottom of the polyslab),

1. Starting from the reference plane, find out the critical extrusion distance for the first vertices degeneracy event when marching towards the top of the polyslab;

2. Construct a sub-polyslab whose base is the polygon at the reference plane and height to be the critical extrusion distance;

3. At the critical extrusion distance, constructing a new polygon that keeps only one of the degenerate vertices;

4. Set the reference plane to the position of the new polygon, and repeating 1-3 to construct sub-polyslabs until reaching the top of the polyslab, or all vertices collapsed into a 1D curve or a 0D point.




Construct a structure containing a user-specified medium and a GeometryGroup made of all the divided PolySlabs from this object.

Inherited Common Usage


Construct a structure containing a user-specified medium and a GeometryGroup made of all the divided PolySlabs from this object.


medium (MediumType) – Medium for the complex polyslab.


The structure containing all divided polyslabs made of a user-specified medium.

Return type:



Hash method.