PortSpec

PortSpec(
    description,
    width,
    limits,
    num_modes=1,
    polarization=None,
    target_neff=None,
    path_profiles=(),
    added_solver_modes=0,
    voltage_path=None,
    current_path=None,
    default_radius=0,
    impedance=None,
)

Optical or electrical port specification.

This class is mainly used to create optical or electrical waveguide templates for a Technology.

Args

• description (str): Description of the port specification.
• width (float): In-plane dimension of the port.
• limits (Sequence[float]): Out-of-plane bounds of the port.
• num_modes (int): Number of modes supported by this port.
• polarization (Literal[“TE”, “TM”, ""] | None): Mode polarization selection.
• target_neff (float | None): Target effective index for numerical mode solving. If None, the square root of the largest real permittivity among the technology media within limits at the mode solving frequencies is used.
• path_profiles (Iterable[tuple[float, float, str | tuple[int, int]]] | dict[str, tuple[float, float, str | tuple[int, int]]]): Tuples with (width, offset, layer) describing the path profiles that make up this port’s geometry. Each path profile tuple can be named by using a dictionary.
• added_solver_modes (int): Additional modes to solve for in mode solver runs (useful when filtering modes by polarization). These are not included in S parameters computed for ports of this type.
• voltage_path (Sequence[Sequence[float] | complex] | None): Sequence of vertices that make up the integral path for voltage calculation in this port. If an empty sequence is used, the path will be set automatically, if possible.
• current_path (Sequence[Sequence[float] | complex] | Rectangle | Circle | Polygon | Path): Sequence of vertices that make up the integral path for current calculation in this port. A planar structure can be used to define the integral over its contour. If an empty sequence is used, the path will be set automatically, if possible.
• default_radius (float): Default radius used for bends created with this specification.
• impedance (complex | Interpolator | None): Complex impedance as a single or frequency-dependent interpolated value (in ohms). If set to None, calculation is performed by mode-solving when needed.

Note

If all of voltage_path, current_path, and impedance are None, the resulting specification will be classified as optical. Otherwise, it will be an electrical port specification.

Important

Ports whose specifications differ only in target_neff connect directly, so circuit simulations that mix them might give an incorrect result. In such cases, it is advisable that the specifications also differ in some other way to avoid connecting them directly.

Example

>>> port_spec = pf.PortSpec(
...     "Single mode strip",
...     1.5,
...     (-0.5, 0.75),
...     path_profiles=[(0.45, 0, (1, 0)), (3, 0, (1, 2))],
... )

See Also

Ports guide

Methods

Method	Description
combined_with	Create a port specification combining this with with a second one.
copy	Create a copy of this port specification.
get_paths	Return a list of paths generated by this specification.
inverted	Return an inverted version of this port if it is asymmetric.
path_profile_for	Return the path profile in this port specification for a specific layer.
path_profiles_list	Return the path profiles in this port specification as a list.
profile_matches	Test if the path profiles in this specification match another’s.
symmetric	Return a flag indicating whether this port specification is symmetric.
to_tidy3d	Create a Tidy3D ModeSolver from this port specification.
to_tidy3d_impedance_calculator	Create a Tidy3D ImpedanceCalculator from this port specification.

combined_with

combined_with(self, port_spec, offset=0)

Create a port specification combining this with with a second one.

The combined port specification is a copy of this one with additional path profiles from port_spec.

Args

• port_spec (PortSpec): Port specification with the path profiles to be added.
• offset (float): Added offset to the new path profiles.

Returns

PortSpec: Combined profile.

Note

The combined specification terminals do not have names.

copy

copy(self)

Create a copy of this port specification.

Returns

PortSpec: New copy.

get_paths

get_paths(self, origin, scale_width=True)

Return a list of paths generated by this specification.

Args

• origin (Sequence[float] | complex): Origin of the generated paths.
• scale_width (bool): Flag passed to Path to indicate whether the width of the created paths should scale when the paths are scaled.

Returns

list[tuple[tuple[int, int], Path]]: List of layer and paths.

inverted

inverted(self)

Return an inverted version of this port if it is asymmetric.

Returns

PortSpec: Inverted specification (self, if symmetric).

path_profile_for

path_profile_for(self, layer, technology=None)

Return the path profile in this port specification for a specific layer.

Args

• layer (str | tuple[int, int]): Layer for desired the profile.
• technology (Technology | None): Technology specification for this specification.

Returns

tuple[float, float] | tuple[list[float], list[float]]: Width(s) and offset(s) for the selected layer.

Note

If the port specification includes several path profiles for the selected layer, width and offset are returned as lists.

path_profiles_list

path_profiles_list(self)

Return the path profiles in this port specification as a list.

Returns

list[float, float, tuple[int, int]]: List of width, offset, and layer from this port specification’s path profiles.

profile_matches

profile_matches(self, port_spec)

Test if the path profiles in this specification match another’s.

Args

• port_spec (PortSpec): Port specification to test.

Returns

bool: Match flag.

symmetric

symmetric(self)

Return a flag indicating whether this port specification is symmetric.

Returns

bool: Symmetry flag.

to_tidy3d

to_tidy3d(
    self,
    frequencies,
    mesh_refinement=None,
    group_index=False,
    technology=None,
)

Create a Tidy3D ModeSolver from this port specification.

Args

• frequencies (Sequence[float]): Sequence of frequency values for the mode solver.
• mesh_refinement (float | None): Minimal number of mesh elements per wavelength used for mode solving.
• group_index (bool): Boolean indicating whether the mode solver should include group index computation.
• technology (Technology | None): Technology specification for this specification.

Returns

ModeSolver: Tidy3D mode solver.

to_tidy3d_impedance_calculator

to_tidy3d_impedance_calculator(
    self, extrapolate_to_endpoints=True, snap_to_grid=True
)

Create a Tidy3D ImpedanceCalculator from this port specification.

The impedance calculator can be used with mode solver data from this port specificatin to calculate its impedance. Only electrical port specifications support this method.

Args

• extrapolate_to_endpoints (bool): Set to ignore fields outside the voltage integration path bounds.
• snap_to_grid (bool): Snap integral paths to the data grid.

Returns

ImpedanceCalculator: Tidy3D impedance calculator.

Attributes

Attribute	Description
added_solver_modes	int: Additional modes to include in mode solver runs for this port.
classification	Literal[‘optical’, ‘electrical’]: Port spec classification: optical or electrical (read only).
current_path	ndarray | None: Current integration path (for electrical port specifications only).
default_radius	float: Default radius for bends.
description	str: Port spec description.
impedance	Interpolator | None: Impedance interpolator (for electrical port specifications only).
limits	ndarray: Out-of-plane limits.
num_modes	int: Number of modes supported by this port.
path_profiles	Iterable[tuple[float, float, tuple[int, int]]] | dict[str, tuple[float, float, tuple[int, int]]]: Path profiles.
polarization	Literal[‘TE’, ‘TM’, ”]: Mode polarization selection.
properties	Properties: Object properties.
target_neff	float | None: Target effective index for port modes (None for the default).
voltage_path	ndarray | None: Voltage integration path (for electrical port specifications only).
width	float: In-plane width.

added_solver_modes

int: Additional modes to include in mode solver runs for this port.

classification

Literal[‘optical’, ‘electrical’]: Port spec classification: optical or electrical (read only).

current_path

ndarray | None: Current integration path (for electrical port specifications only).

default_radius

float: Default radius for bends.

description

str: Port spec description.

impedance

Interpolator | None: Impedance interpolator (for electrical port specifications only).

limits

ndarray: Out-of-plane limits.

num_modes

int: Number of modes supported by this port.

path_profiles

Iterable[tuple[float, float, tuple[int, int]]] | dict[str, tuple[float, float, tuple[int, int]]]: Path profiles.

polarization

Literal[‘TE’, ‘TM’, ”]: Mode polarization selection.

properties

Properties: Object properties.

target_neff

float | None: Target effective index for port modes (None for the default).

voltage_path

ndarray | None: Voltage integration path (for electrical port specifications only).

width

float: In-plane width.